Consolidated Index (A-Z)

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A-B-C-D-E-F-G-H-I-J-K-L-M-N-O-P-Q-R-S-T-U-V-W-X-Y-Z

A

ABC model of the control of flowering

ABC transporter

ABL gene

ABO blood groups

ABP1 (Auxin-binding protein 1)

Abscisic acid (ABA)

Abscission

Absorption spectrum

Abyssal plain

ACE inhibitors

Acetylcholine: [at neuromuscular junction]

Acetyl-CoA

Acid

Acid rain

Acorn worms

Acrosome

ACTH (adrenocorticotropic hormone; aka corticotropin)

Actin filaments: [Discussion] [in cytokinesis] [in skeletal muscle]

Actinomycetes

Action potential: [in muscle fiber]

Action spectrum

Active transport

Activins: [in embryonic development] [sex hormones]

Acute lymphoblastic leukemia (ALL)

Adaptation: [of sense receptors] [evolutionary]

Adaptive radiation

Addison's disease

Adenine

Adeno-associated virus (AAV).: as vector for somatic gene therapy

Adenomatous Polyposis Coli (APC) gene

Adenosine deaminase (ADA): and severe combined immunodeficiency (SCID)

Adenosine triphosphate (ATP)

Adenoviruses

Adenylyl cyclase: [and odorant receptors]

ADH, the antidiuretic hormone (also known as vasopressin

Adherens junctions

Adhesion: Force of attraction between unlike molecules.

Adipose tissue (fat): [secretion of leptin by]

Adjuvant

Adrenal glands, hormones of

Adrenaline

Adrenocorticotropic hormone (ACTH; aka corticotropin)

Advanced waste treatment

Adventitious root

Aequorin

Aerobic: Requiring the presence of free oxygen.

Affinity: Strength of binding by noncovalent interactions between one site on a molecule and a monovalent ligand. [antibody affinity] [affinity maturation]

Afrotheria

AGAMOUS (AG)

Agent Orange

Aging

Agnatha

Agonist: Drug that mimics the action of another. [Example]

Agrobacterium tumefaciens

AID (Activation-Induced cytidine Deaminase)

AIDS (Acquired Immune Deficiency Syndrome)

Air: [composition of] [pollution]

AIRE (autoimmune regulator gene)

Alanine

Alcohols

Aldehydes

Aldosterone

Algae: [Brown] [Green] [Golden] [Red] [culture medium for]

Alkylation: Addition of a carbon-containing group, such as a methyl or ethyl group, to another molecule.

Allantois

Allele: Alternative version of a gene. [in Mendel's peas] [in a three-point cross] [RFLPs] [hemoglobin beta chain] [and protein polymorphisms]

Allergen: An antigen that provokes an allergic response.

Allergy

Allograft

Allopatric speciation

Allosteric: Refers to a change in the properties (usually including shape) of a protein following the binding of another molecule to the protein. [Example]

Allozyme

Alpha1-Antitrypsin: [deficiency ] [synthesis by transgenic sheep] [and emphysema]

Alpha helix

Alpha motor neurons

Alport's syndrome

Alternation of generations: [Discussion] [in ferns] [in mosses]

Alternative splicing

Alu element

Aluminum

Alvarez, L.

Alveolates

Alveoli

Alzheimer's disease

Ames Test

Amfor gene

Amides

Amines

Amino acids

Aminoglycosides

Aminopeptidase

Amino terminal

Ammonia: [in nitrogen cycle] [in urea cycle]

Amniocentesis

Amnion: [in humans]

Amniota

AMPA receptors

Amphetamines

Amphibians

Amphineura

Amphioxus

Amphiphilic: Used to describe molecules containing both polar (hydrophilic) and apolar (hydrophobic) groups. Sodium stearate (a soap) is amphiphilic.

Amygdala

Amylase: [pancreatic amylase]

Amylin

Amyloid

Amylopectin

Amylose

Anabolic steroid

Anabolism

Anaerobic: Not requiring the presence of free oxygen.

Analgesics

Analogous: Of structures (e.g., molecules, organs) in different species having similar function(s) but inherited from different precursors.

Anammox (anaerobic ammonia oxidation)

Anaphase: [in mitosis] [in meiosis]

Anaphase-Promoting Complex/Cyclosome (APC/C)

Anaphylaxis: [local] [systemic]

Androgen

Anemia: [immune hemolytic] [pernicious] [sickle-cell]

Anesthetic

Aneuploid: Having one or more extra (or fewer) chromosomes than the normal diploid (2n) set (e.g., 2n+1, 2n-1). [trisomy 21] [X chromosomes]

Angelman syndrome

Angiogenesis

Angiosperms: [life cycle] [evolutionary relationships]

Angiotensin

Angiotensin converting enzyme (ACE)

Angstrom (Å)

Animal: [cells] [invertebrate] [tissues] [vertebrate]

Aniridia gene

Annelida

ANP (atrial natriuretic peptide)

Antennapedia (Antp): [encoded homeodomain]

Antenna pigments

Anther

Antheridia: [in ferns] [in mosses]

Anthozoa

Anthrax: [how its toxin works]

Antibiotics

Antibody: [structures] [classes] [how their diversity is created] [affinity] [binding to antigen] [bispecific] [monoclonal] [specificity]

Anticodon

Antidepressant drugs

Antidiuretic hormone (ADH)

Antigen

Antigenic determinant: A part of an antigen to which the antibody binds. Also called an epitope. [View]

Antigenic drift of influenza viruses

Antigen presentation

Antigen-Presenting Cells (APCs)

Antigen receptors on B and T cells: how their diversity is created

Antimicrobial peptides

Antioxidants

Antiport pump.

Antisense strand: The strand of DNA used as the template for synthesizing RNA. (Sometimes called the Watson strand.) [View] [Antisense oligonucleotides] [Antisense RNA]

Antiserum: Serum containing induced antibodies. [Example]

Antithrombin III

Antithymocyte globulin (ATG)

Antitoxin

Aorta

APC gene

APETALA

Apical dominance

Apicomplexa

Apicoplast

Apis mellifera, the honeybee: [life history] [communication]

Aplysia

Apolipoprotein B: [and cholesterol metabolism] [and RNA editing]

Apomixis

Apomorphic

Apoplast

Apoptosis: Programmed cell death. [Discussion]

Aposematic coloration

Appetite, control of

Aquaporin

Aqueous humor

Arabidopsis thaliana

Arachidonic acid

Arachnida

Archaea

Archegonia: [in ferns] [in mosses]

Archenteron

ARF1 (Auxin response factor 1)

Arginine: [substrate for NO synthases]

Arrestins

Arteries and Arterioles

Arteriosclerosis

Arthropods

Ascidians

Ascomycetes

Ascorbic acid (vitamin C)

Ascus

Asexual reproduction

Asparagine

Aspartic acid

Assisted Reproductive Technology (ART)

Association constant (K)

Assortative mating

Asthma

Astrocytes

Ataxia telangiectasia: [ATM gene] [and aging]

Atherosclerosis: [and cholesterol]

Atom

Atomic number

Atomic weight unit: One-twelfth the weight of an atom of carbon-12. Also called the dalton. [More]

Atopy

ATP (adenosine triphosphate): [structure] [yield in cellular respiration]

ATP-binding cassette

ATP synthase: [in photosynthesis] [in mitochondria]

Atrial natriuretic peptide (ANP)

Atrio-ventricular (A-V) node

Atrium

Australopithecus afarensis

Autocrine: Refers to the influence on a cell of molecules synthesized by the same cell. [More]

Autoimmune disease: Disease characterized by the mounting of an immune response against constituents of an individual's own tissues. Some examples: [Goodpasture's Syndrome] [Type 1 diabetes mellitus] [Immune hemolytic anemia] [Immune thrombocytopenic purpura] [Myasthenia gravis (MG)] [Multiple sclerosis (MS)] [Rheumatoid arthritis] [Systemic lupus erythematosus (SLE)] [Thyrotoxicosis (Graves' disease)]

Autonomic nervous system

Autophagy

Autoradiography

Autosome: Any chromosome that is not a sex chromosome.

Autotrophic

Capable of synthesizing organic molecules from inorganic raw materials.

Photoautotrophs use light as the source of the needed energy. Characteristic of plants, algae, and some bacteria. [Photosynthesis]
Chemoautotrophs use the energy secured by oxidizing some inorganic substance in their surroundings. Characteristic of certain bacteria and archaeons.

Auxin: [actions] [and tropisms] [differential action on roots and shoots]

Avena test

Avery, O. T.

Avogadro's number

Axial element

Axon: [axon hillock]

Azathioprine

AZT: Azidodeoxythymidine. Also called zidovudine.

B

B7: Refers to 2 similar transmembrane molecules (B7.1 & B7.2) that are expressed at the surface of antigen-presenting cells. B7.1 is also known as CD80; B7.2 as CD86. [View]

Bacillus: [anthracis] [subtilis] [thuringiensis]

Bacteria: [Descriptions of the "true" bacteria (Eubacteria)]

Bacteriophage: Virus that infects bacteria. [lambda] [phiX174 (φX174)] [T2] [T4]

Bacteroidetes

Balanced polymorphism

Barbiturate

Barcoding

Barr body

Base: Molecule or ion that can take a proton from an acid. [Discussion]

Base Excision Repair (BER) of DNA

Base pairing of DNA

Basidiomycetes

Basophil

Bats: [echo location in] [vampire]

Bax

B cell: A lymphocyte that synthesizes antibodies. Antibody-secreting cells, called plasma cells, are derived from B cells. [Discussion] [interaction with helper T cells] [how antibody diversity is generated]

BCL-2: [Role in apoptosis]

BCR: (the oncogene)

BCR: B-cell receptor for antigen [Discussion] [how its diversity is generated]

Beadle, G. W.

Behavior: [Innate] [Learned] [Group]

Benthos

Benzer, S.

Benzodiazepines

Beta-carotene

Beta conformation (in protein)

Beta-galactosidase: An enzyme (e.g., "lactase") that hydrolyzes the disaccharide lactose and related molecules. [synthesis by Z gene of lac operon]

Beta-2 microglobulin

bicoid (bcd): Drosophila selector gene. [encoded homeodomain] [in segmentation] [role in forming the head]

Bilaterians

Bile acids

Bioassay: Quantitative determination of the concentration of a biologically active substance from its effect on a living tissue. [Example]

Biochemical oxygen demand (BOD)

Bioluminescence

Biological Control of Pests

Biomagnification, of pesticides

Biomass: The total amount of living matter in a given population or community.

Biomes

Biosphere: The part of our planet in which life exists and with which it exchanges materials. Includes a small part of the lithosphere (the solid earth) and large parts of the hydrosphere (water) and atmosphere.

Biotin

Bipolar cells of human retina

Birds

Birth control

Birth, human

Biston betularia

Bivalent

Bivalvia

Blastema

Blastocyst: The blastula formed by placental mammals. The blastocyst is the embryonic stage that implants in the wall of the uterus. [human]

Blastula: Early stage of animal development in which a single (usually) layer of cells surrounds a fluid-filled cavity (the blastocoel), thus forming a hollow ball. [frog]

Blind spot on human retina

Blood: [general discussion] [clotting] [blood groups] [blood pressure]

Blood-brain barrier

Blue-green algae (Cyanobacteria)

Bmal1 gene

BNP (brain natriuretic peptide)

Bond energy

Bonds: [covalent] [ionic] [polar covalent] [noncovalent]

Bone

Bone marrow: [transplants of]

Bone Morphogenetic Proteins (BMPs): [in embryonic development]

Botany: The study of plants.

Bovine spongiform encephalopathy (BSE)

Boysen-Jensen

Bradykinin

BRAF

Brain, human

Branchial grooves

Brassinosteroids

BRCA1 and BRCA2

Breathing: [control of] [in insects]

Bristol's Medium

Bromodeoxyuridine (BrdU)

Bruton's tyrosine kinase (Btk)

Bryophyta

Bt (Bacillus thuringiensis)

Budding: Asexual reproduction in which a new organism develops from an outgrowth of a single parent. [Example]

Burkitt's lymphoma

C

C4 plants

Cadherins

Caenorhabditis elegans: [ general discussion ] [genome] [germline vs somatic cells] [measuring mutation rate in] [evolutionary advantage of outcrossing in]

Calciferol

Calcineurin (calcium-calmodulin-dependent phosphatase)

Calcitonin

Calcitriol

Calcium: [in nutrition] [homeostatic regulation of] [as "intracellular messenger"]

Calcium-calmodulin-dependent kinase II (CaMKII)

Calorie: The amount of heat required to raise the temperature of 1 g of water 1 degree Celsius. When capitalized, a unit of heat 1000 times larger than the above.

Calorie Restriction (CR)

Calvin cycle

Cambium: [in stems] [in roots]

Cambrian period

CaMKII: Calcium-calmodulin-dependent kinase II

CAM plants

cAMP Response Element Binding (CREB) protein

Cancer: Any disease characterized by an uncontrolled proliferation of one kind of cell. [GENERAL DISCUSSION]; Related Topics:; [and Apoptosis] [Burkitt's Lymphoma] [Cancer Cells in Culture] [Caused by Power Lines?] [Chemotherapy] [Chronic Myelogenous Leukemia] [Colon Cancer] [Estimating Risk] [Immunotherapy] [Lung Cancer] [Oncogenes] [and Telomeres] [Tumor Suppressor Genes] [The Causes and Prevention of Cancer" by Bruce Ames]

Capillaries

Capping of pre-mRNA

Capsaicin

Carbamates

Carbohydrates

Carbon cycle

Carbon dioxide: [in cellular respiration] [in photosynthesis] [control of breathing] [control of heartbeat] [transport by blood] [as greenhouse gas]

Carbonic anhydrase

Carbonyl group

Carboxylic acids

Carboxyl terminal

Carboxypeptidase

Carcinogen: A substance that causes cancer.

Carcinoma: A cancer of epithelial cells.

Cardiac (heart) muscle

Carotenoid

Carpel

Carrying capacity (K) of the environment

CAR-T cells

Cartilage

Cartilaginous fishes (Chondrichthyes)

Casparian strip

Caspase

Catabolism

Catabolite activator protein (CAP)

Catalase

Catalyst: Substance that accelerates the rate of chemical reaction without being used up in the process. Enzymes are catalysts.

Cataracts

Catecholamines

Catenins: [in adherens junctions] [as transcription factors]

Cathelicidins

CCK (Cholecystokinin)

CCR3 (CC chemokine Receptor 3)

CCR5 (CC chemokine Receptor 5)

CD ("cluster of differentiation") molecules: [CD1] [CD3] [CD4] [CD8] [CD19] [CD20] [CD22] [CD25] [CD28] [CD33] [CD34] [CD47] [CD52] [CD80 (= B7-1)] [CD86 (= B7-2)] [CD95]

cDNA: DNA produced in vitro by the reverse transcription of a messenger RNA

Cell-mediated immunity

Cells: [Animal cells] [Plant cells] [Cell Cycle] [Cell Junctions] [Cell membranes] [Cell signaling]

Cellular respiration: [Discussion] [energy relationships in]

Cellulose

Cenozoic era

Centimorgan (cM)

Central dogma

Central nervous system (CNS), human

Centriole

Centromere

Centrosome: [general discussion] [in mitosis]

Cephalopoda

Cephalosporins

Cercariae

Cerebellum

Cerebrospinal fluid (CSF)

Cestoda: [pig and fish tapeworm life cycles]

Chaparral

Chaperones and chaperonins: [in protein folding] [in protein kinesis]

Character Displacement

Chargaff's rule

Chase, Martha

Checkpoints: in the cell cycle

Checkpoint inhibitors

Chelicerata

Chemiosmosis: [in chloroplasts] [in mitochondria] [laboratory demonstration]

Chemoautotrophic: Autotrophic, using energy secured by oxidizing some inorganic substance. Characteristic of certain bacteria and archaeons.

Chemokine: A cytokine that attracts white blood cells (WBCs). These secreted proteins regulate the migration of WBCs from the blood into the tissues and promote inflammation. Some are also essential for proper embryonic development. Over 40 different chemokines have been identified. [some examples]

Chemotaxis

Chemotherapy: Treating a patient with chemicals to combat an infectious disease or cancer. [drugs used in cancer chemotherapy]

Chernobyl (aka Chornobyl): [radiation] [effect of fallout]

Chiasma

Chimera

Chimpanzee: [genome] [evolutionary relationships] [learned behavior] [immunodeficiency virus (SIV)]

Chitin: [inhibitors as insecticides]

Chlamydia

Chlamydomonas

Chloracne

Chlorinated hydrocarbons, as insecticides

Chlorination of water supplies

Chlorofluorohydrocarbons (CFCs) and ozone layer

Chlorophyll

Chlorophyta

Chloroplasts: [structure] [chemiosmosis in] [genome]

Choanoflagellates

Cholecystokinin (CCK)

Cholera: [the cause] [1991 epidemic]

Cholesterol: [uptake by cells]

Cholinesterase

Chondrichthyes (cartilaginous fishes)

Chondroitin sulfate

Chordata: Invertebrate chordates

Chordin

Chorion

Chorionic gonadotropin

Chorionic villus sampling (CVS)

Choroid coat

Chromatid

Chromatin: Chromatin Immunoprecipitation (ChIP)

Chromatography: [affinity chromatography] [exclusion chromatography] [paper]

Chromatophores

Chromosomes: [discussion] [chromosome maps] [chromosome painting] [harlequin] [sex chromosomes] [polytene chromosomes]

Chronic granulomatous disease (CGD)

Chronic myelogenous leukemia (CML): [discussion] [mutation]

Chronic obstructive pulmonary disease (COPD)

Chrysophyta (golden algae}

Chymotrypsin

Chytrids

Cigarettes and health

Cilia

Ciliates

Ciona intestinalis

Cipro®

Circadian: Occurring approximately once a day. [Discussion of circadian rhythms in Drosophila and mammals]

Circulatory system: [human: structure and function] [fish, squid, frog, lizard] ["open"]

Cistron

Citric acid cycle

Citrulline

Cladistics

Cleavage: [in frog]

Cline

Clinical studies: clinical trials of drugs

Cloaca: Posterior part of the alimentary canal into which the urinary and reproductive tracts empty in birds, reptiles, amphibians, monotremes, and many fishes. [View]

Clock (clk) gene

Clonal selection in the immune system: Some experiments

Clone: The descendants produced asexually from a single cell or organism. Characterized by a identical genetic constitution. [cloning DNA] [cloning animals]

Clonus

Clostridia

Clotting (coagulation) of blood

Cnidaria

Cocaine

Cochlea

Cockayne's syndrome

Codominance: The independent expression of each of two alleles in a heterozygote.

Codon: [DNA codons] [RNA codons] [mRNA translation] [exceptions to the code]

Coelacanth

Coelom: Main body cavity of many animals. It is lined with an epithelium derived from mesoderm.

Coenzyme

Cohesin

Cohesion: Force of attraction between like molecules.

Cold receptors

Coleoptile

Collagen

Collective dose

Collenchyma

Color blindness

Colostrum

Commensalism

Community: The population of plants, animals, and microbes found in a particular area and often interacting with one another.

Companion cell

Competition: [intraspecific] [interspecific]

Competitive inhibition: of enzymes

Complementarity Determining Regions (CDRs)

Complementary DNA (cDNA): A DNA molecule synthesized (by reverse transcriptase) from an RNA template. When the template is messenger RNA (mRNA), the cDNA represents an intronless gene.

Complementation, genetic

Complement system

Compound

Compound eye, of arthropods

Computed tomography (CT)

Concepts

Condensins

Conditioned Response

Conditioning, instrumental or operant

Cones: of human retina

Confidence limits

Conidia

Conifers

Conjugation: [bacterial conjugation] [in Paramecium]

Connective tissue

Connexins

Consumer: (primary, secondary, etc.)

Contact sensitivity: [a case study] [contact dermatitis]

Contig: A DNA sequence assembled by matching overlaps of individual DNA fragment sequences. [View]

Continental drift

Contraception

Contraceptive, oral

Convergent evolution

COPI and COPII (Coat proteins I and II)

Corepressor

Cornea

Coronary system

Corpora allata

Corpus luteum

Cortex: The outer part of an organ.

Corticotropin-releasing hormone (CRH)

Cortisol

Corynebacteria

Cottony cushion scale insect

Cotyledon

Countercurrent exchangers

Covalent bond

COVID-19: Coronavirus Disease 2019

Cowpox

COX: Initials used for two entirely different molecules: cytochrome c oxidase and cyclooxygenase

CpG sites: Places in a single strand of DNA where the sequence is 5' Cytosine-phosphate-Guanine 3'. In vertebrates, this sequence occurs less often than would be expected by chance. However, CpG sites are found at higher frequency in some regions of the genome called CpG islands. CpG islands are often found close to gene promoters and may affect the level of gene transcription.

Cranial nerves

Craniata

Creatine phosphate

Creighton, Harriet

Cre/loxP

Crenarchaeota

Creutzfeldt-Jakob disease (CJD)

Crick, F.

CRISPR loci (clustered regularly interspaced short palindromic repeats): and gene editing in eukaryotes

Cristae in mitochondria

Crossing over: [in meiosis] [molecular mechanism]

Cross-presentation (of antigens)

Crustacea

Cryptochrome: [and circadian rhythms] [and germination] [and etiolation] [and photoperiodism in plants]

Cryptomonads

csd ("complementary sex determiner") gene

C terminal

Cushing's syndrome

C value: [C-value paradox]

CXCR4

Cyanobacteria

Cycads

Cycle (cyc) gene

Cyclic ADP ribose

Cyclic AMP (cAMP)

Cyclic GMP (cGMP)

Cyclic photophosphorylation

Cyclin

Cyclooxygenase (COX-1 and COX-2): [COX-2 inhibitors] [and pain]

Cyclosporine

Cysteine

Cysticercosis

Cystic fibrosis (CF): [mutations]

Cytidine deaminase

Cytochrome: [in mitochondria] [in chloroplasts] [cytochrome c sequences in different species]

Cytokine: Protein secreted by a cell that signals other cells in a paracrine fashion or even itself (autocrine). The various lymphokines, chemokines, interferons, colony-stimulating factors, and tumor necrosis factors are examples. [cytokine receptors]

Cytokinesis

Cytokinins: Plant hormones.

Cytomegalovirus (CMV)

Cytoplasm: General term for all the contents of the cell outside the nucleus and within the plasma membrane.

Cytosine

Cytoskeleton

Cytosol: The fluid in which the organelles of the cytoplasm are suspended. Also called the ground substance of the cell.

Cytotoxic T lymphocyte (CTL)

D

Dalton: Unit of mass equal to one-twelfth the mass of an atom of carbon-12 and therefore close to the mass of a hydrogen atom. [More]

Danio rerio (the zebrafish)

Darwin, Charles: [Darwin's finches] [experiments on phototropism]

DDT (dichloro, diphenyl, trichloroethane): [biomagnification of]

Deafness

Deamination: Removal of an amino group (-NH₂) from a compound. [Equation]

decapentaplegic (dpp)

Decarboxylation: Removal of carbon dioxide from the carboxyl group of an organic acid. [in cellular respiration]

Decay in nutrient recycling

Defensins

Delayed-type hypersensitivity (DTH)

Deletions: [DNA] [mapping with]

Demographic transition

Denaturation: (1) Proteins: Alteration of the physical properties and three-dimensional structure by agents too mild to break the peptide bonds. [More] (2) DNA: Separation of the two strands of the double helix (sometimes called "melting"). [More]

Dendrite

Dendritic cells: Dendritic-cell vaccines

Dendrogram: See phylogenetic tree.

Denitrification

Deoxyribonucleic acid (go to DNA)

Deoxyribose

Desert biome

Desmosomes

Deuterostomes

Diabetes: [mellitus] [insipidus]

Diacylglycerol (DAG)

Diakinesis

Dialysis: [equilibrium dialysis]

Diapsids

Diastole

Diatoms

Dicer

Dicots: [stem structure]

Dieldrin

Dietary Reference Intakes (DRIs)

Differentiation: Structural and functional modification of an unspecialized cell into a specialized one.

Diffusion

Digestion

Dihybrid: Heterozygous at two different gene loci. [examples]

Dinoflagellates

Dioecious: Having female sex organs on one plant, male on another. The holly is dioecious. [and self-incompatibility]

Dioxin: [in milk]

Diphtheria

Diphyllobothrium latum

Diploid: Having two of each kind of chromosome (except for the sex chromosomes); 2n; [numbers]

Diplotene

Diptera: [anatomy]

Disaccharide

Disruptive selection

Dissociation: Separation of ions from a molecule or crystal lattice. [image]

Distal: Situated away from the place of origin or attachment.

Disulfide bridge (in proteins)

Dixon, H. H.

DNA: Polymer of deoxyribonucleotides that stores genetic information. [Structure: the Double Helix] [DNA chips] [DNA-DNA hybridization] [DNA fingerprinting] [DNA ligase] [DNA polymerase] [DNA recombination] [DNA repair] [DNA Replication] [DNA vaccines] ["Immortal" Strands] [Mitochondrial DNA (mtDNA)] [Pyrosequencing] [Recombinant DNA and Gene Cloning] [Repetitive DNA] ["Selfish" DNA] [Sequencing by the dideoxy method]

DNA polymerase: An enzyme that catalyzes the polymerization of deoxyribonucleotides to form DNA complementary to a template (either DNA or, in the case of reverse transcriptase, RNA). [More]

DNase I

Dolly: First mammal (a sheep) cloned from an adult cell. [More]

Domains, protein

Dopamine: [as hormone] [as neurotransmitter]

Dose-response relationships

Double-stranded breaks (DSBs) in DNA

Doubling times

Down syndrome (trisomy 21)

Drosophila melanogaster (with links to many subtopics): also [diploid number] [genome size] [selector genes] [early embryonic development] [segmentation of the embryo]

Drugs: [clinical testing] [psychoactive] [proteins made by recombinant DNA technology]

Duchenne Muscular Dystrophy (DMD)

Ductus arteriosus

Duplication: [mutation]

Dyad: A chromosome and its duplicate that was synthesized during S phase, while still connected by their single shared centromere. The two chromosomes of the dyad are known as sister chromatids. The chromatids of the dyad separate at anaphase of mitosis and of meiosis II. [Diagram] [in meiosis]

Dynein

Dystrophin

E

E. coli: Escherichia coli, a bacterium found in the intestine. [genome] [aging in]

Ear, human

Ecdysone

Ecdysozoans

Echinoderms

Echolocation, in bats

Ecology: Study of the interrelationships of organisms and their environment.

Ecosystem: A community of organisms interacting with each other and with their nonliving surroundings.

Ectoderm

Ectodermin

Ectotherm

Edema

Effector: Body structure by which an organism acts. In humans the chief effectors are the muscles and glands.

Efferocytosis

Egestion: Elimination of undigested materials from the alimentary canal. [More]

Ehlers-Danlos syndrome

Elastase: [pancreatic] [neutrophil]

Elastins

Electric organs (and electroreceptors)

Electron

Electronegative: Having an affinity for electrons. [More]

Electron Transport Chain

Electrophoresis

Element

ELISA (Enzyme-linked immunosorbent assay)

Embryo

An animal or plant in an early stage of development from a zygote. The development of animal embryos is analyzed in 4 pages:

Embryonic stem (ES) cells: (general discussion with links to other pages)

Emphysema

Enantiomer

Encephalitozoon cuniculi

ENCODE (Encyclopedia of DNA Elements)

Endocrine: Refers to hormones. [discussion of human hormones] [table of human hormones] [insect hormones]

Endocytosis: [by B lymphocytes]

Endoderm

Endodermis

Endoplasmic reticulum (ER)

Endoreplication

Endosomes

Endosperm

Endostatin

Endosymbiont: An organism living within the body (or cell) of its symbiotic partner. [origin of mitochondria and chloroplasts]

Endotherm: An animal that maintains its body temperature with heat generated by its metabolism.

Endotoxin

End plate potential (EPP): [More]

Energy: Capacity for doing work. [free energy]

Enhancer: Region of DNA that stimulates the initiation of the transcription of a gene. Enhancers differ from promoters in being farther away from, and either upstream (5') or downstream (3') of, the gene they influence. [Discussion]

Enkephalins: [More] [view enkephalin synapse]

Enzyme-linked immunosorbent assay (ELISA)

Enzymes: [Restriction Enzymes] [ Enzyme Kinetics]

Eosinophils

Eotaxin

Epiblast: The layer of the inner cell mass of amniotic embryos which will develop into ectoderm and mesoderm [Link]. See Hypoblast.

Epicotyl: That portion of the shoot of a plant embryo or seedling above the node at which the cotyledons are attached. [View]

Epidemiology

Epigenetics

Epiphyseal plate

Epiphyte

Epithelia

Epitope: A part of an antigen to which an antibody binds. Also called an antigenic determinant. [View]

Epstein-Barr virus (EBV): [genome] [and apoptosis] [how it evades cell-mediated immunity]

Equilibrium: State of balance between opposing actions. [sense of equilibrium in humans] [equilibrium dialysis]

Erythrocyte (red blood cell)

Erythropoietin (EPO): [the hormone] [and somatic gene therapy]

Escherichia coli: [genome]

Esters

Estrogen

Ethers

Ethylene (as plant hormone)

Etiolation

Euarchontoglires

Eubacteria

Euchromatin

Eugenics: The application of genetics in an attempt to "improve" the hereditary qualities of humans.

Euglenozoa

Eukaryote: An organism whose cells contain a membrane-enclosed nucleus and usually other membrane-enclosed organelles such as mitochondria and plastids. Includes all living things except the bacteria and archaeons. Sometimes spelled eucaryote.

Euryarchaeota

Eustachian tube

Eutheria (placental mammals)

Eutrophication

even-skipped (eve): [role in Drosophila embryo]

Evolution: [and adaptation] [and speciation] [convergent] [of Homo sapiens] [and mutations] [and development ("Evo-Devo")]

Excitatory postsynaptic potential (EPSP)

Excretion: Elimination of metabolic wastes by an organism. [in humans] [in other vertebrates]

Exocrine: Refers to glands that deposit their secretion(s) into ducts that drain to the "exterior". [discussion] [view topology] Compare endocrine.

Exocytosis

Exon: Portion of a gene that is retained in the messenger RNA (mRNA) molecule. Adjacent exons are separated from each other by introns. Often exons encode one domain of a protein. The ability to shuffle exons in different combinations may — over the course of evolution — have speeded up the creation of new genes with new functions. [More]

Exosome: Term unfortunately used for two entirely-different cell structures: (1) tiny vesicles released by the cell for various types of cell-to-cell signaling [View], e.g., antigen presentation, and (2) complexes used for RNA degradation.

Exponential growth

Expressed Sequence Tags (ESTs)

Extensor

Extracellular fluid (ECF)

Extracellular matrix (ECM)

Extraembryonic membranes

Extrinsic allergic alveolitis

Eye: [of humans] [of insects] [induction of]

eyeless (ey) gene

F

Fab fragment

Facilitated diffusion

Facilitation

Factors, clotting

Fallopian tube

Farmer's lung

Farsightedness (hypermetropia)

Fas and its ligand (FasL): [in apoptosis] [and immune privilege] Fas is also known as CD95.

Fascia

Fatal Familial Insomnia (FFI)

Fat: [nutritional requirement] [molecular structures] [with trans fatty acids] [omega-3] [adipose tissue]

Fauna: Animal life.

Fc fragment

Feedback inhibition

Fermentation: Anaerobic decomposition of an organic compound (e.g., glucose) by a living organism. [glycolysis]

Ferns: [life cycle] [evolutionary relationships]

Ferredoxin

Fertility (F) factor

Fertilization, in humans

Fetus: Unborn vertebrate after it has largely completed the development of its organ systems (in humans, after about 2 months). [circulatory system]

Fibrin

Fibroblasts

Fibronectin

Firmicutes

Fishes: [ circulatory system ]

Fission: Asexual reproduction by division of the body into two or more equal parts.

Fissure of Rolando

Fitness, evolutionary

Flagella

Flatworms (phylum Platyhelminthes)

Flexor

Flora: Plant life.

Florigen

Flow cytometry

Flower: Illustrated discussion

Flowering, genetic control of

"Flu": Influenza. Discussion

Flukes, blood

Fluorescence: Emission of light by a substance following absorption of radiation of a different wavelength.

Fluorescence-Activated Cell Sorter (FACS)

Fluorescence in situ hybridization (FISH): [muscle glycogen phosphorylase DNA] [bcr/abl DNA]

Fluoride

fMRI (functional Magnetic Resonance Imaging)

F_oF₁-ATPase

Folic acid (folacin): [analogs used as antibiotics]

Folkman, J.

Follicle

Follicle-stimulating hormone (FSH)

Food chains and webs

Footprinting

for ("foraging") gene

Foramen ovale

fos gene

Fossil: Any remains of an organism or evidence of its presence that has been preserved in the earth.

Founder effect

Fovea

FoxP2 ("foxhead box protein P2")

FoxP3 ("foxhead box protein P3")

Fragile X syndrome

Free energy: [ and membrane transport ]

Freshwater ecosystems

Frizzled

Frog: [embryology] [ circulatory system ] [View]

Fructose: and obesity

Fruit

FSH (follicle-stimulating hormone)

Fungi

G

G₁, G₂, G₀: [phases of cell cycle]

GABA receptors

Gage, Phineas

Galactose

Galapagos Islands

Games parasites play

Gamete: Haploid reproductive cell which, after fusion with another gamete, forms a zygote. [More]

Gametophyte: Haploid, gamete-producing stage in the life cycle of a plant. [Discussion] [in angiosperms] [in ferns] [in mosses]

Gametophytic self-incompatibility (GSI)

Gamma aminobutyric acid (GABA) Receptors

Gancyclovir (also spelled ganciclovir)

Ganglion: Small mass of nerve tissue containing the cell bodies of neurons. [sympathetic ganglia]

Ganglion cells: [of human retina] [in visual processing]

Gap junctions

Gas constant

Gas exchange: [in humans] [in other vertebrates] [in insects] [in leaves and stems]

Gastrin

Gastropoda

Gastrulation: [in frog embryo]

Gaucher's disease

G band

Gel blotting

Geminin

Gene conversion

Gene Drive

Gene flow

Gene locus: Location of a particular gene (or one of its alleles) on a chromosome. [examples]

Gene pool

Generator potential

Genes, reporter

Gene therapy: [using retroviral vectors] [using an adeno-associated virus (AAV) vector] [using no vector]

Genetic code

Genetic drift

Genetic mosaics

Genetic testing: [sickle-cell disease] [with in vitro fertilization]

Genome: A complete haploid set of genes. [genome sizes] [The Human Genome Projects] [mitochondrial] [chloroplast]

Genotype: Genetic constitution of an individual.

Genus: A taxonomic category that includes (usually) several closely related species. Similar genera are grouped in a family. Humans (Homo sapiens) belong to the genus Homo.

Geological eras and periods

Germination: Resumption of growth of the embryo within a seed, or of a spore. [germination in seeds]

Germline

Gerstmann-Sträussler-Scheinker disease (GSS)

Ghrelin

giant (gt): [role of gene in Drosophila segmentation]

Gibberellins

Gibbs, Josiah Willard

Gill slits: Paired openings from the pharynx to the exterior that occur in many aquatic chordates when the gill pouches open out at the branchial grooves. [View]

Girdling

Glands: [exocrine] [endocrine]

Gleevec® (also known as STI571 and imatinib mesylate)

Glia

Global warming

Glomerulus

Glucagon

Glucocorticoids: [Discussion] [receptor bound to response element]

Gluconeogenesis

Glucose: [structure] [homeostatic regulation of]

Glutamic acid: [structure] [as neurotransmitter]

Glutamine

Glycation

Glycerol

Glycine: [structure] [as neurotransmitter]

Glycogen

Glycogenolysis

Glycolysis

Glycopeptide antibiotics

Glycophorin A

Glycoproteins

Glycosidic bond

Glycosylation

Goiter

Golgi apparatus: [Discussion] [in protein kinesis]

Gonad: Organ that produces gametes, sperm in males, eggs in females. In humans, the gonads also make sex hormones.

Gonadotropin-releasing hormone (GnRH)

Gondwana

Gonorrhea

Goodpasture's syndrome

gp120

G-protein-coupled receptors (GPCRs): [odor receptors] [pheromone receptors] [peptide hormone receptors] [taste receptors] [rhodopsin] [GABA_B receptors] [opioid receptors] [serotonin receptors] [Ca²⁺ receptor]

G proteins

Grafting (in plants)

Graft rejection: [mechanism] [preventing]

Graft-versus-host disease (GVHD): Immune attack against the host mediated by T cells in a transplanted organ or tissue (e.g., bone marrow). [More] [still more]

Graft-versus-leukemia

Gram stain

Grana

Grant, P. and Rosemary Grant

Granulocyte: One of the three types of leukocytes (white blood cells) that contain granules in their cytoplasm. Neutrophils, eosinophils, and basophils are the granulocytes. [More]

Granulocyte colony-stimulating factor (G-CSF)

Granzymes

Grassland biome

Graves' disease: Also called thyrotoxicosis. [More]

Gravitropism: [mechanism]

Gray (Gy)

Gray crescent

Green algae

Green fluorescent protein (GFP)

Greenhouse effect

Griffith, F.

Growth: Increase in the size of an organism, resulting from an increase in its number of cells, their size, the amount of extracellular matrix, or all of these. [human growth hormone]

Guanine

Guillardia theta

Gustducin

Gymnosperms

H

HAART: Highly Active AntiRetroviral Therapy (for AIDS)

Habitat: The type of site where an organism normally lives.

Habituation

Haeckel, E.

Hair cells

Half-life: The time needed for (1) half the atoms of a radioactive substance to decay or (2) half the amount of a substance (e.g., a drug) to be metabolized or excreted.

Haltere

HAMA: human antimouse antibodies

Ham's medium

Haploid: Having only a single set of chromosomes (n) as is present in gametes. Also called monoploid.

Haplotype

Hardy-Weinberg equilibrium

Harlequin chromosomes

Haversian canal

HDL (high-density lipoprotein)

Hearing, sense of

Heart: [anatomy of human heart ] [ control of human heart ] [ fish heart ] [ frog and lizard hearts ] [ squid hearts ]

Heat receptors

Heat transport

Hedgehog signaling

HeLa cells

Helicase

Helicobacter pylori: [adaptation to stomach]

Heliotropism

Helix-turn-helix proteins

Helper T cells: [Discussion] [Interaction with B cells]

Hemagglutinin: of influenza virus

Hematocrit

Heme

Hemichordata

Hemidesmosomes

Hemizygous: Genes present in only one copy, not two, in an otherwise diploid cell or individual. Human males are hemizygous for most of the genes on the X chromosome.

Hemoglobin: A red, iron-containing protein that transports oxygen and carbon dioxide in the blood of vertebrates and some invertebrates. [More] [sickle-cell] [in different species]

Hemophilia: [A, B, C] [Inheritance]

Heparan sulfate

Heparin

Hepatic portal system

Hepatitis B

HER1 and HER2

Herbaceous: Nonwoody.

Herbicides

Herbivore: An animal that eats plants.

Hereditary angioedema (HAE)

Heritability

Herpesviruses

Hershey, A. D.

Hertz: Cycles per second.

Heterochromatin

Heterodimer: Complex of two different proteins.

Heteroduplex DNA

Heteroplasmy

Heterotrophic: Requiring a supply of organic compounds (food) from the environment. [ More ]

Heterozygous: Having two different alleles (e.g., A and a) at the corresponding gene loci on homologous chromosomes.

Hexapoda (the insects)

Hexose

Hippocampus

Histidine

Histocompatibility molecules: [class I] [class II] [minor] [genes that encode them] [structure of HLA-A2]

Histones: [ histone acetyltransferases (HATs) ] [ histone deacetylases (HDACs) ]

HIV, the Human Immunodeficiency Virus: [how it evades the immune system]

HLA: human leukocyte antigen [structures] [genes]

Homeobox: A sequence of 180 base pairs which encodes a 60-amino acid homeodomain found in many DNA-binding proteins. Genes containing homeoboxes are found in all eukaryotic genomes.

Homeostasis: Maintenance of a relatively constant internal environment (ECF).

Homeothermic: Having a constant body temperature above that of the usual surroundings; therefore, "warm-blooded".

Hominoid: Group of primates that includes hominids and hominins. [Discussion]

Homodimer: Complex of two identical protein molecules.

Homo habilis

Homologous: Showing a fundamental similarity of structure because they have been inherited from a common ancestor. Applied to structures ranging from organs to molecules.; [illustrated discussion] [chromosome pairs]

Homoplasmy

Homozygous: Having identical alleles (e.g., AA or aa) at the corresponding gene loci on homologous chromosomes.

Honeybees (Apis mellifera): [life history] [honeybee communication]

Hormesis

Hormone: Substance secreted by cells in one part of the body which, after being transported by body fluids, exerts an effect on the activities of cells elsewhere in the body. [of humans] [of insects] [sex hormones] [of plants]

Horsetails

Hox gene clusters: [in Drosophila, mouse, and human]

HTLV-1: and adult T-cell leukemia/lymphoma (ATL)

Hubel, D. H.

Human Genome Project (HGP)

Human papilloma virus (HPV): [interaction with tumor suppressor genes] [and apoptosis] [vaccine]

Humus

hunchback (hb): [role of gene in Drosophila segmentation]

Huntington's disease: [mutation]

Hutchinson-Gilford progeria syndrome

Hyaluronic acid

Hybrid: Organism produced by genetically dissimilar parents. It is heterozygous for one or (more often) many pairs of genes.

Hybridization

Hydrocarbons

Hydrogen bond: [ in DNA ]

Hydrolysis: Decomposition of a substance by the insertion of water molecules between certain of its bonds. Food is digested by hydrolysis.

Hydronium ion

Hydrophilic: Used to describe molecules or molecular groups that are attracted to water and other polar solvents.

Hydrophobic: Used to describe molecules or molecular groups that mix poorly with water. Hydrocarbons and fats are hydrophobic. [hydrophobic interactions between macromolecules]

Hydroxyl group

Hydroxyl radical

Hypercholesterolemia, familial

Hypertension

Hypertonic solutions

Hypervariable regions

Hypoblast: The layer of the inner cell mass of amniotic embryos which will develop into endoderm [Link]. See Epiblast.

Hypocotyl: That portion of the shoot of a plant embryo or seedling below the node to which the cotyledons are attached. [View]

Hypothalamus: [hormones of]

Hypothesis: [testing] [null]

Hypotonic solutions

I

IAA (Indole-3-acetic acid)

ICAM-1 (InterCellular Adehesion Molecule-1)

I-cell disease ("inclusion-cell disease")

IgA: A class of antibody molecules abundant in tears, colostrum, and other secretions. [More]

IgE: A class of antibodies responsible for certain immediate hypersensitivities (allergies). [More]

IgG: The class of antibody molecules that is most abundant in the blood. [More]

Ilyanassa obsoleta

Imatinib mesylate (also known as Gleevec® and STI571)

Immune globulin (IG)

Immune privilege

Immune surveillance

Immune System: [anatomy] [antigen receptors] [B cells and T cells] [clonal selection] [generation of antigen receptor diversity]

Immunity: [adaptive vs. innate] [adaptive immunity in prokaryotes] [cell-mediated] [active vs. passive] [complete list of topics]

Immunological memory

Immunological synapse

Immunological tolerance: The inability to produce antibodies and/or a cell-mediated immune response to a particular antigen.

Immunosuppression: The use of drugs or other agent (e.g., x rays) to inhibit an immune response. [More]

Immunotoxin

Impact hypothesis

Implantation

Imprinting: [genomic or parental (the preferential expression of the allele inherited from one parent or the other)] [in animal behavior]

Inbreeding

Incretins

Indels

Independent assortment of genes

Indian pipe

Indole-3-acetic acid

Industrial melanism

Inflammasome

Inflammation

Influenza

Ingestion

Inhibitory postsynaptic potential (IPSP)

Innate Lymphoid Cells (ILCs)

Inner Cell Mass: [of mouse blastocyst] [of human blastocyst]

Inorganic: Term describing all compounds that do not contain carbon as well as a few simple carbon-containing substances such as carbon dioxide and the carbonates.

Inositol-1,4,5-trisphosphate (IP₃)

Insecticides

Insects: [insect hormones] [orders of]

Insertions (in DNA)

Instincts

Insulators

Insulin

Insulin-like growth factor: [Igf-1] [Imprinting of Igf-2 gene (as well as that of its receptor)]

Integral membrane proteins

Integrase

Integrins: [and angiogenesis]

Inteins

Interferon (IFN)

Interleukins

Cytokines that regulate development and activities of leukocytes. [in blood cell formation] [interactions with helper T cells]

Intermediate filaments

Intermediate host: Host normally used by a parasite during an immature or larval stage of the parasite's life cycle. [of tapeworms] [of blood flukes]

Interneuron

Interphase

Interstitial fluid: The fluid lying between, and thus bathing, the cells of animals. Interstitial fluid (also called extracellular fluid — ECF) is derived from blood. Lymph is derived from it.

Intertidal zone

Intestine

Intracytoplasmic Sperm Injection (ICSI)

Intrauterine devices (IUDs)

Intrinsic factor

Introgression

Intron: Portion of a gene that is transcribed into RNA but is removed during the formation of the mature RNA molecule. Found in rRNA and tRNA genes as well as in genes encoding proteins. Most eukaryotic genes have introns; most genes in bacteria and archaea do not. [More] [Group I] [Group II]

Invariant (Ii) chain

Invertebrates

Inverted repeats

In vitro: Done in the "test tube".

In Vitro Fertilization (IVF): [prior genetic screening]

In vivo: Refers to experiments performed in the living organism.

Iodine

Ion: Atom or group of atoms that has an electrical charge arising from the gain or loss of electrons.

Ion channels in cell membranes

Ionic bond: Chemical bond formed between ions of opposite charge. [More]

Iron: [nutritional requirement]

Islets of Langerhans

Isoleucine

Isomer: Molecule with the same molecular formula as another but with a different structural formula (e.g., glucose and fructose). [optical isomers]

Isometric: The contraction, without shortening, of a muscle. [More]

Isotonic: (1) Adjective to describe the contraction of a muscle that is allowed to shorten as it exerts a steady force. (2) Having the same concentration of water as the solution under comparison. (More)

Isotope: Atom that differs in weight from other atoms of the same element because of a different number of neutrons in its nucleus. [Discussion]

J

JAK-STAT pathway ["JAnus Kinase-Signal Transducer and Activator of Transcription"]

Jasmonates

Jenner, Edward

Joly, J.

jun gene

Junctional epidermolysis bullosa (JEB)

Juvenile hormone (JH): [as insecticide]

K

Kallikrein

Kandel, E. R.

Kaposi's sarcoma herpesvirus (KSHV)

Karyotype: [of normal human male]

Keratan sulfate

Keratin: [in intermediate filaments]

Ketones

Kidney: [anatomy and physiology] [hormones of] [comparative vertebrate kidneys]

Kinase: Enzyme that attaches phosphate groups. The human genome encodes 518 different kinases that add phosphate groups to proteins. [Tyrosine kinases]

Kinesin

Kinetochore: [and mitosis] [and meiosis]

Kin Selection

Kisspeptin

Klamath weed

Klinefelter's syndrome

Klotho

Knockout mice

Krebs cycle

Krüppel gene

K-strategists

K-T boundary

Kuffler, S. W.

Ku protein (a dimer of Ku70 and Ku80)

Kuru

L

lac operon: [Discussion] [using it to detect mutations in mice] [using it to detect cell-specific gene expression]

lac repressor: [Discussion] [isolating by affinity chromatography]

Lactase

Lacteal

Lactose

Lagging strand (DNA)

Lamarck, J-B

Laminins

Lamins

Larva: Immature stage of many animals that must undergo metamorphosis to become an adult. [trochophore larva] [insect larva]

Latent period

Lateral geniculate nucleus (LGN): [human] [in visual processing]

Laurasia

Laurasiatheria

LD₅₀: [ of insecticides ]

LDL (low-density lipoprotein)

Leaf: [structure] [gas exchange in]

LEAFY protein

Learning

Legume: A member of a family of pod-bearing plants that includes peas, beans, clovers, alfalfa (lucerne), and so on. [and symbiotic nitrogen fixation]

Lens of human eye

Lenticels

Leptin

Leptotene

Leucine

Leukemia: A cancer characterized by the uncontrolled proliferation of a clone of leukocytes circulating in the blood. Compare with Lymphoma.
[Chronic Myelogenous Leukemia (CML)] [Chronic Lymphocytic Leukemia (CLL)] [Acute Lymphoblastic Leukemia (ALL)]

Leukocyte

Leukotrienes (LTs): [ inhibitors for treating asthma ]

Lewis, E. B.

LFA-1 (Leukocyte Function-associated Antigen-1)

LH (Luteinizing hormone)

Licensing factors

Lichens

Liddle's syndrome

Ligaments

Ligand: A molecule that binds to another molecule or to a cell.

Light-harvesting complexes (LHCs)

Lignin: Complex substance found in the cell walls of sclerenchyma and xylem tissue, which are strengthened by it.

Limbic system

Limiting dilution analysis

Limnetic zone

LINES (Long Interspersed Elements)

Lineweaver-Burk plot

Linkage: Tendency of two genes to be inherited together because they are located on the same chromosome. [Discussion]

Lipase

Lipids: Hydrophobic organic molecules such as triglycerides (fats and oils) and some steroids. [serum lipids]

Lipopolysaccharide (LPS; also known as endotoxin)

Lipoprotein

Listeria monocytogenes

Littoral zone

Liver: [hormones of] [physiology]

Liverworts

Lizard, heart of

Locus: The position that a gene occupies in a DNA molecule or the chromosome containing that DNA. [Example]

Logistic growth curve

Long-term: depression (LTD); facilitation; potentiation (LTP); sensitization

Long Terminal Repeats (LTRs)

Loop of Henle

Lophotrochozoans

Lorenz, K.

Lorenzo's Oil

Loss of heterozygosity (LOH)

Lovastatin

LPS (lipopolysaccharide; also known as endotoxin)

LUCA (Last Universal Common Ancestor)

Luciferase

Lumen: The cavity inside a tubular structure such as a blood vessel or kidney tubule.

Lung cancer

Lungs: [ human] [other vertebrates]

Luteinizing hormone (LH)

Lycopsids

Lyme disease

Lymph

Lymph Nodes: Where B cells and T cells meet antigens; Role of follicular helper T cells (Tfh)

Lymphocyte: [ T cells and B cells ]

Lymphoid: Referring to lymphocytes or tissues (e.g., lymph nodes) in which lymphocytes are a major constituent.

Lymphokine: Protein secreted by lymphocytes that affects their own activity and/or that of other cells. Most of the interleukins are lymphokines. Lymphokines represent a subset of cytokines. [examples]

Lymphoma: A cancer characterized by the uncontrolled proliferation of a clone of lymphocytes forming solid masses in the body. Compare with Leukemia.
[Burkitt's lymphoma]

Lymphotoxin: Cytokine that triggers apoptosis. Also known as tumor necrosis factor-beta (TNF-β) [More]

Lysergic acid diethylamide (LSD)

Lysine

Lysis: The disintegration of a cell following damage to its plasma membrane. [hemolysis]

Lysogeny

Lysosomes

Lysozyme: [ structure ]

M

mab-5: C. elegans gene [see encoded homeodomain]

Macrolide antibiotics

Macromolecule: A molecule with a molecular weight of several thousand or more. Proteins, nucleic acids, cellulose, and starch are macromolecules.

Macronucleus

Macrophage

Macrophage colony-stimulating factor (M-CSF)

MAD: mitotic arrest defective

Mad cow disease

Magnetic resonance imaging (MRI)

Magnetoencephalography (MEG)

Magnetoreceptors

Magnetotaxis

Major histocompatibility complex (MHC): A cluster of genes, some of whose products are involved in presenting antigens to T cells and also serve as the principal targets of graft rejection. Found in most, if not all, vertebrates. The MHC of humans is on chromosome 6 and is designated HLA. [diagram of the complex] [the class I and class II histocompatibility molecules]

Malaria: [Life cycle of Plasmodium vivax] [evading host immunity]

Malignant: Refers to a cell that cannot stop dividing; also to the tumor that results. Cancerous.

Maltose

Mammals: orders of placental mammals

Mandibulata

Mangold, Hilde

Marijuana

Marine ecosystems

Mars (life on?)

Marsupial: Any of the order of pouched mammals such as opossums, wombats, and kangaroos. [Discussion] [pregnancy and birth]

Mast cell: [role in allergies]

Matrix: (1) Extracellular material in which animal cells are embedded, especially those of connective tissue [More]. (2) Fluid contained within the inner membrane of mitochondria.

Maximum sustainable yield

Mayr, E.

McClintock, Barbara: [and transposons] [demonstration that genetic recombination of linked genes occurs by chromosome crossovers]

MCM proteins ("minichromosome maintenance proteins")

Mechanoreceptors

Medulla: Inner part of an organ.

Medulla oblongata

Megakaryocyte

Megaspore

Meiosis

Melanocyte-stimulating hormone (MSH)

Melanopsin

Melatonin

Membrane Attack Complex

Memory: [Implicit and Explicit] [and long-term potentiation (LTP)]

Memory cells of immune system

Mendel, G.: [his monohybrid crosses] [his second rule]

Meninges

Menopause

Menstrual cycle

Meprobamate

Meristem: [in roots] [in stems]

Merkel cells

Meselson, M. S.

Mesoderm

Mesophyll

Mesozoic era

Metabolism: Exchange of matter and energy between an organism and its environment and the transformation of this matter and energy within the organism.
[General discussion with links to specific examples] [Intermediary]

Metabolite: A substance used in or produced by metabolism.

Metabolome

Metagenomics

Metamorphosis, insect

Metaphase: [in mitosis] [in meiosis I]

Metastasis: A secondary growth of malignant (cancer) cells away from the site of the primary tumor. [More]

Metazoa (the animals)

Methane: a greenhouse gas

Methanogens

Methionine

Methyl group: [structure] [methylation of DNA] [methylation of histones]

Michaelis-Menten constant

Microglia

Micron (µ)

Micronucleus

Microorganism: An organism of microscopic size such as bacteria, protozoans, and many algae. Also called a microbe.

Micropyle

MicroRNAs (miRNAs)

Microspore

Microsporidia

Microtubules

Microvilli

Mifepristone (RU486): [More] [and Birth Control]

Miller, Stanley

Millisievert (mSv)

Mimicry

Mineralocorticoids

Minerals: [nutritional requirements] [Recommended Dietary Allowances (RDAs)]

Miniature Inverted-repeat Transposable Elements (MITEs)

Miracidium

Mismatch repair of DNA

Mitochondrial Eve

Mitochondrial stimulation factor (MSF)

Mitochondrion: [structure and functions] [genome] [diseases]

Mitosis: Nuclear division that follows duplication of the chromosomes, whereby each daughter nucleus has exactly the same chromosome content as the parent nucleus. [Discussion] [ and cell cycle]

Mixtures

Mole

Molecular clocks

Molecular weight

Molecule: Smallest particle of a covalently bonded element or compound that retains the properties of that substance.

Mollusks

Molt: To shed the outer covering. [in insects] [disruptors as insecticides]

Monoamine oxidase (MAO) inhibitors

Monoclonal antibodies: [for treatment of cancer]

Monocots: [stem structure]

Monocyte

Monoecious: Having both female and male cones or flowers on the same plant. [More]

Monoglyceride: Glycerol carrying a single fatty acid.

Monohybrid cross

Monomer: Simple molecular unit that can be linked with others to form a polymer. The glucose molecule is the monomer of starch.

Monoplacophora

Monosaccharide

Monotremes: Egg-laying mammals (Prototheria) [Discussion]

Morgan, T. H.

Morphology: Study of structure.

Mosaics, genetic

Mosses

Motor unit

M-phase promoting factor (MPF)

MPS-I (mucopolysaccharidosis I)

Multiple alleles: More than two alleles found at a give gene locus in a population. [example in plants] [example in humans]

Multiple factors: Nonallelic genes that affect the same trait in an additive fashion. [More]

Multiple myeloma

Multiple sclerosis: [as autoimmune disease]

Murchison meteorite

Muscarinic acetylcholine receptors

Muscles: [Discussion of skeletal, cardiac, and smooth muscle] [testing the sliding-filament model of muscle contraction]

Muscle spindles

Muscular dystrophy

Mutagen: Agent that causes mutations. [Ionizing radiation] [Testing chemical mutagens in bacteria] [Testing chemical mutagens in mice]

Mutation: [general discussion] [SUMMARY] [and evolution] [germline vs somatic] [in B-cell antibody genes] [by transposons] [temperature-sensitive]

Mutualism

Myasthenia gravis

myc: [and Burkitt's lymphoma]

Mycelium

Mycobacteria: [uptake by cells] [Mycobacterium leprae genome]

Mycoplasma: [genomes of]

Mycorrhiza

Myelin sheath

Myeloid: Refers to all the blood cells except the lymphocytes.

Myeloma protein: The immunoglobulin (antibody) produced by a cancerous clone of plasma cells. [View]

Myeloperoxidase

Myofibrils

Myoneural junction (also called a neuromuscular junction)

Myosin

Myostatin

Myriapoda

Myxobacteria

Myxoma virus

N

N-acetylglucosamine (NAG)

nanos: [role of gene in Drosophila segmentation] [establishing the tail of the Drosophila embryo]

Natural Killer (NK) Cells

Natural selection: [types] [effect on gene pool]

Nearsightedness

Nekton

Nematoda

Neoantigen

Nephron

Neritic zone

Nerve: Bundle of axons.

Nervous system: [human central nervous system (CNS)] [human peripheral nervous system (PNS)]

Net productivity

Neural folds

Neuraminidase of influenza virus

Neuromuscular junction

Neuron: A nerve cell. [Structures] [Function]

Neuropeptide Y

Neurospora crassa

Neurotransmitter: Substance released at the axon terminals of a neuron that either stimulates or inhibits the next neuron or muscle fiber. Acetylcholine and noradrenaline are neurotransmitters. [Discussion]

Neutron

Neutrophil

NF-AT ["Nuclear Factor of Activated T cells]

NF-κB ["Nuclear Factor - kappa B"]

Niacin: Nicotinic acid, one of the B vitamins.

Niche: The place in a biological community occupied by a particular species in its relation to other species.

Nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP): Coenzymes that transfer electrons within the cell. [Discussion and structure] [in Calvin cycle] [from light reactions] [NADH dehydrogenase]

Nicotinic acetylcholine receptors

Nilsson-Ehle, H.

Nitric oxide (NO): [physiological functions]

Nitrification

Nitrogen cycle

Nitrogen fixation: The conversion of atmospheric nitrogen (N-N) into nitrogen-containing compounds like ammonia. [Discussion] [symbiotic]

Nitrogen oxides (NO_x): [and acid rain] [and photochemical smog]

NKT Cells

N-linkage

NMDA receptors

Nociceptors (pain receptors)

Nodal

Node: (1) In plants, the point on the stem at which one or more leaves develop. [diagram] (2) of Ranvier

noggin gene

Nondisjunction

Nonhomologous End-Joining (NHEJ)

Nonsense-Mediated mRNA Decay (NMD)

Noradrenaline (norepinephrine)

Northern blot

NO synthases (NOS)

Notch signaling

Notochord: [in frog embryology]

N-regions of antigen receptor genes

NSAIDs: nonsteroidal anti-inflammatory drugs (e.g., aspirin)

N-terminal

Nuclear localization sequence

Nuclear Pore Complexes (NPCs)

Nuclease: An enzyme that hydrolyzes a nucleic acid, DNA or RNA. Examples: DNase I, Ribonuclease P.

Nucleic acid: A polymer of nucleotides; DNA and RNA.

Nucleolus

Nucleoside

Nucleosomes

Nucleotide: [Antisense oligonucleotides]

Nucleotide Excision Repair (NER) of DNA

Nucleus

Nucleus accumbens

Nude Mouse

Null hypothesis

Nutrition: [requirements] [gastrointestinal (GI) tract]

O

Oceanic zone

Okazaki fragment

OKT3: [More]

Olfaction, the sense of smell

Oligonucleotide: A short polymer of, for example, 20 or so deoxyribonucleotides or ribonucleotides; thus a fragment of DNA or RNA.

Ommatidia

Oncogenes

Oncogenic: Cancer causing.

One Gene - One enzyme Theory

Ontogeny: The development of an individual organism from fertilization to maturity.

Oogenesis

Oomycetes

Ooplasmic transfer

Open Reading Frame (ORF): DNA sequence beginning with ATG and read in triplets until it ends with a STOP codon. An ORF is potentially able to encode a polypeptide.

Operator: A DNA sequence in bacteria to which a repressor or activator protein binds, turning off (or on) transcription of the associated genes of the operon.

Operon: A set of adjacent genes and the operator that controls them. [lac operon]

Opioids: [and pain relief]

Opsin

Opsonin

Organ: Group of tissues that performs a specific function for an animal or plant (e.g., stomach, leaf).

Organelle: Specialized part of a cell (e.g., mitochondrion) analogous to an organ.

Organic: Term describing all compounds whose molecules contain carbon, with a few exceptions such as carbon dioxide and carbonates. [types and functional groups]

Organism: Individual living being.

Organizer (in frog embryology)

Organ of Corti

Organophosphates

Origin of Life

Origin Recognition Complex (ORC)

Ornithine

Orthologous genes: Homologous genes in different species; thus genes that have descended from a gene in the common ancestor of those species. Compare paralogous genes.

Osmosis

Osmotic pressure: [in guard cells of leaf] [in phloem] [in capillaries] [in kidney function] [and root pressure]

Ossicles

Osteichthyes (bony fishes)

Osteoclasts and osteoblasts

Osteogenesis imperfecta

Osteomalacia

Osteoporosis and calcium

Otoliths

Ovary

Ovulation: [role of hormones in]

Ovule

Oxidation: Process of removing electrons from a substance. [in mitochondria]

Oxygen: [transport by blood] [in cellular respiration] [in photosynthesis (More)] [in breathing] [Bond energies (More)] [Electronegativity] [Redox potential]

Oxytocin

Ozone: Highly active form of oxygen (O₃ instead of O₂). [ozone hole] [and photochemical smog]

P

p16^INK4a: [tumor suppressor gene] [and aging]

Pachytene

Pacinian corpuscle

Packaging cell (for retroviral gene vectors)

Pain

Paleozoic era

Palindromes

Pancreas: [hormones of] [digestive enzymes]

Pandemic

Paneth cells

Pangaea

Para-aminobenzoic acid (PABA)

Paracrine: Refers to the influence on a cell of chemical signals released by neighboring cells. Compare autocrine and endocrine.

Parainfluenza virus (PIV)

Paralogous genes: Genes in one species that have arisen by duplication of an ancestral gene. Example: genes encoding olfactory receptors. Compare orthologous genes.

Paramecium caudatum

Paraphyletic: A term in taxonomy used to describe a group of organisms sharing a common ancestor (thus members of a clade) but that excludes one or more groups within that clade. Thus the class Reptilia is a paraphyletic group because reptiles share a common ancestor with the separately-classified birds (class Aves) and mammals (class Mammalia). An example. Another example.

Parasitism: [How parasites evade host defenses]

Parasympathetic nervous system

Parathion

Parathyroid hormone (PTH)

Parenchyma

p arm

Parthenogenesis: [ and imprinting ]

Passive immunity

Patch clamp technique

Patch test (for contact dermatitis)

Pathfinder mission to Mars

Pathogen: Disease-causing organism or virus.

Pathogen-Associated Molecular Patterns (PAMPs)

Pattern Recognition Receptors (PRRs)

Pax6

P bodies

PCR (polymerase chain reaction)

Pdx-1 gene

P element

Pemphigoid and pemphigus

Penicillin

Pentose

Pepsin

Peptidase: Enzyme that hydrolyzes peptides into amino acids.

Peptide bond

Peptidoglycan

Perforin

Pericycle

Period (per) gene

Peripheral membrane protein: [Schematic (48K)]

Peripheral nervous system, human

Peroxisome-proliferator-activated receptors (PPARs)

Peroxisomes: [ peroxisomal targeting signal (PTS) ]

Peroxyacetyl nitrate (PAN)

Peroxyl (or peroxy) radical

PERV (porcine endogenous retrovirus)

Peto's Paradox

Peyote

pH: [effect on enzyme action]

Phage display

Phagocytosis

Pharyngula

Phencyclidine (PCP)

Phenotype: Appearance of an organism, resulting from the interaction of its genotype and its environment.

Phenylalanine

Phenylketonuria (PKU)

Pheromones: [insect] [in mammals]

Philadelphia chromosome (Ph¹)

PhiX174 (φX174)

Phloem: [function in translocation] [structure] [in roots]

Phosphatase: Enzyme that removes phosphate groups

Phosphate group

Phospholipids

Photoperiodism, in plants

Photophosphorylation

Photorespiration

Photosynthesis: [Calvin cycle] [light reactions] [energy relationships in] [history]

Photosystems I & II

Phototaxis

Phototropin: [ and phototropism ] [ and stomatal opening ]

Phototropism

Phylogenetic tree: [of hominoids]

Phylogeny: Evolutionary history of a species.

Phylum

Physiology: Study of the processes occurring in living organisms.

Phytochrome: [in etiolation] [in photoperiodism]

Pigment: Substance that absorbs light, often selectively. [antenna pigments] [absorption spectra]

Pilin

Pineal gland

Pinocytosis

PIN proteins

Pistil

PISTILLATA (PT)

Pituitary gland, hormones of

Pitx1

Placenta: [functions] [hormones] [as an allograft]

Plague

Planarian

Plankton

Plant: [cells] [growth] [kingdom] [succession] [tissues] [Sexual Reproduction in]

Plasma: Fluid matrix of the blood. [Discussion]

Plasma cell

Plasma membrane

Plasmid

Plasmin

Plasmodesmata

Plasmodium falciparum: [immune evasion]

Plasmodium vivax

Plasmolysis

Plastocyanin (PC)

Plastoquinone (PQ)

Platelets: [ and blood clotting ]

Platyhelminthes (the flatworms)

Pleiotropy: The production by a single gene of more than one effect on the phenotype.

Plesiomorphic

Plumule: Terminal bud of a plant embryo, usually consisting of embryonic leaves and the epicotyl. [Picture]

Pluripotent stem cells

Pneumococci (Streptococcus pneumoniae): [rough and smooth] [types] [genome]

Poikilothermic: Having a body temperature that fluctuates with that of the surroundings. Commonly, "cold-blooded".

Polar body: [genetic screening of]

Poliovirus

Pollination

Polyadenylation

Polymer: Compound whose molecule consists of many repeated units linked together.

Polymerase chain reaction (PCR)

Polymorphism

Polyol

Polyp: Abnormal growth of tissue that is still benign and polyclonal. Some polyps tend in time to develop a malignant clone of cells. [in colon]

Polypeptide: [polypeptide antibiotics]

Polyploidy

Polysaccharide

Polysome: [in protein synthesis] [picture]

Polytene: Used to describe the multistranded ("giant") interphase chromosomes found in certain metabolically active cells of insects.

Polytene chromosomes

Pons

Populations: [ how regulated ] [ human ] [ cycles ]

Porifera (the sponges)

Porphyria, inheritance of

Positron-emission tomography (PET)

Post transcriptional gene silencing (PTGS)

Postzygotic isolating mechanisms

Potassium channels: involvement in hereditary deafness

Potential: [action potential] [excitatory postsynaptic potential (EPSP)]
[inhibitory postsynaptic potential (IPSP)] [resting potential]

PPM: Parts per million. [More]

Prader-Willi syndrome

Precocenes

Precursor: Substance from which another substance is formed.

Precursor activation

Predation: Living by devouring other organisms.

Pregnancy: [in humans] [hormones]

Premature termination codons (PTCs)

Pre-messenger RNA (pre-mRNA)

Prenatal Diagnosis

Pressure-Flow theory

Prezygotic isolating mechanisms

Primary host: Host normally used by a parasite during the adult stage of its life cycle.

Primary structure (Protein)

Primary transcript

Primates

Primitive: Similar to that occurring in the early evolutionary history of the structure or organism in question.

Primordial germ cells (PGCs)

Prion diseases

Producer: An organism that can synthesize organic molecules from inorganic ones (i.e., an autotroph). Producers start food chains.

Profundal zone

Progeria

Progesterone

Progestin: Any steroid that mimics the effects of progesterone.

Prokaryote: General term used for organisms that are not eukaryotes. Includes two evolutionarily-distinct groups: bacteria and archaeans. Sometimes spelled procaryote.

Prolactin (PRL)

Proline: [structure] [in collagen]

Promoter: Region of DNA, usually on the 5' side of a gene, that is needed for the initiation of the transcription of that gene. RNA polymerase and other transcription factors bind to the promoter. [bacterial promoters] [eukaryotic promoters] [part of response element]

Pronucleus: The sperm nucleus and egg nucleus within the fertilized egg before their fusion to form the diploid zygote nucleus. [in humans] [making transgenic animals]

Proopiomelanocortin (POMC)

Prophage

Prophase: [mitosis][meiosis I]

Proprioception

Prostaglandins: [role in birth] [role in allergies]

Prostate gland

Prosthetic group: The nonprotein part of a conjugated protein. Metal ions and a variety of organic molecules (e.g., vitamins, sugars, lipids) can serve as prosthetic groups. Prosthetic groups are usually bound covalently to their proteins. [More]

Protease: Enzyme that hydrolyzes peptide bonds whether in proteins or peptides. [serine proteases] [of HIV] [inhibitors]

Proteasomes

Proteinase: Enzyme that hydrolyzes the peptide bonds of proteins.

Protein C

Protein chips

Protein Kinases: [PKA (cAMP-dependent)] [and memory] [PKC (calcium-dependent)] [PKG (cGMP-dependent)]

Proteins: [general discussion] [protein synthesis] [protein kinesis] [protein domains]

Proteobacteria

Proteoglycans

Proteome

Prothallus

Prothoracicotropic hormone (PTTH)

Protists

Proton: Positively charged particle found in the nuclei of all atoms. The hydrogen ion (H⁺) is a proton. [More]

Protonema

Proto-oncogene: A normal cellular gene that, when mutated or inappropriately expressed, can cause a cell to become cancerous. Designated c-onc. They normally participate in the control of the cell cycle. [More]

Protoplast: A cell (plant or bacterial) from which the cell wall has been removed.

Protostomia

Protozoa

Proximal: Situated near the place of origin or attachment.

Prozac

Pseudoautosomal region

Pseudocyclic photophosphorylation

Pseudogene

Nonfunctional gene present in the genome of a population. Pseudogenes arise from two different mechanisms:

Processed pseudogenes are DNA copies of mRNAs produced by reverse transcription. They lack introns and often contain a remnant of the poly(A) tail.
Nonprocessed pseudogenes are genes that arose by duplication of an ancestral gene but have since undergone one or more mutations that prevent their expression. Typically they contain introns.

Pseudogenes are designated with the Greek letter psi, e.g., ΨHBBP1 is a nonfunctional version of the gene encoding the beta chain of human hemoglobin. The human genome contains some 19,000 pseudogenes.

Psychedelic drugs

PTTH

Pulmonary system: [human lungs] [their blood supply] [lungs of other vertebrates]

Pupa

Pupil: of human eye

Purines: [analogs used as immunosuppressants]

Pyramids of energy, biomass, and numbers

Pyrethroids

Pyrimidines

Pyrosequencing

PYY_3-36

Q

q arm of chromosome

Quantitative Trait Loci (QTL)

Quaternary structure: Refers to complexes of two or more polypeptide chains held together by noncovalent forces but in precise ratios and with a precise 3-D configuration. [More]

Queen Victoria

Quinolone antibiotics

R

Races (subspecies)

Radiation: [ionizing] [and cancer] [spectrum of electromagnetic radiation]

Radicle: Root portion of the embryo of seed plants. [View]

Radioimmunoassay (RIA)

Radioimmunotherapy

RAF gene

RAG-1 and RAG-2: Recombination Activating Genes

Random assortment of chromosomes in meiosis

Rapamycin: [as immunosuppressant] [as regulator of transgene expression]

RAS gene

Rate of natural increase (r)

RB (retinoblastoma gene)

Reactant: Substance that enters into a chemical reaction.

Reactive oxygen species (ROS)

Recapitulation: Occurrence, in embryonic development, of stages thought to have occurred in the embryonic development of its ancestors. [Discussion]

Receptor editing

Receptor Tyrosine Kinases (RTKs)

Recognition helix

Recombinant DNA

Recombination: [in meiosis] [ in rII locus ] [in T-even bacteriophages] [nodule] [signal sequence (RSS)]

Recommended dietary allowances (RDAs) (table)

Reconsolidation, of memories

Red blood cells

Redox potential

Redox reaction: A chemical reaction in which electrons are transferred from one atom (which is thereby oxidized) to another (which is thereby reduced).

Red Queen hypothesis

Reduction: Process of adding electrons to a substance.

Reductionism

Reflex: [stretch reflex] [withdrawal reflex]

Refractory period: Brief interval following the propagation of an action potential in a neuron or muscle fiber during which it is incapable of propagating a second action potential. [in neurons] [in muscle fibers]

Regeneration

Regulator gene: A gene that encodes a transcription factor and thus controls the expression of other genes.

Relaxin

Releaser

REM (roentgen equivalent man)

Renin

Repetitive DNA

Replication origin

Replicative senescence

Reporter genes

Repressor: [lac repressor] [tryptophan repressor]

Reproduction: [sexual] [asexual]

Reptiles

Resistin

Respiratory burst

Respiratory Syncytial Virus (RSV)

Respiratory system: [human lungs] [their blood supply] [lungs of other vertebrates]

Response element (RE): A particular DNA sequence which, when bound by a protein specific for it, turns its associated gene(s) on (or off). Many response elements bind to a complex of a hormone with its protein receptor. [steroid response elements] [response element of a protein hormone]

Resting potential

Restriction endonuclease: An enzyme that cuts DNA molecules at, or close to, a certain sequence of nucleotides. [Discussion]

Restriction fragment length polymorphism (RFLP)]

Reticular formation

Retina, human

Retinal

Retinoblastoma

Retinoids

Retinol (vitamin A)

Retrotransposons

Retrovirus: A virus whose genome consists of RNA which, after infection, is copied by reverse transcriptase into DNA. The human immunodeficiency viruses (HIV) are retroviruses. [life cycle] [as vector in gene therapy]

Reverse transcriptase: An enzyme that catalyzes the synthesis of DNA that is complementary to an RNA template; that is, an RNA-dependent DNA polymerase. [More] [inhibitors]

Rh antigens

Rh disease (hemolytic disease of the newborn)

Rheumatoid arthritis

Rhizobia

Rhizoid: Hairlike structure that serves as a root for bryophytes, fern prothallia, and certain fungi and lichens.

Rhizome: Underground stem. [View]

Rhodophyta (Red Algae)

Rhodopsin

Riboflavin (vitamin B₁₂)

Ribonuclease P (RNase P)

Ribonucleic acid (see RNA)

Ribonucleoprotein: A complex of RNA and protein.

Ribose

Ribosome: [structure] [in protein synthesis] [rRNA genes]

Riboswitches: [and gene transcription] [and mRNA translation]

Ribozyme: [general discussion] [synthetic]

Ribulose bisphosphate carboxylase oxygenase (RUBISCO): [in photosynthesis] [genes] [and photorespiration]

Rickets

Rickettsias

Rifampin

Risk, relative

Ritalin

Rituximab

RNA: Ribonucleic acid. A polymer of ribonucleotides.
[messenger RNA (mRNA)] [ribosomal RNA (rRNA)] [transfer RNA (tRNA)] [small nuclear (snRNA)] [small nucleolar RNA (snoRNA)] [guide RNA (gRNA)] [antisense RNA] [small interfering RNA (siRNA)] [microRNAs (miRNAs)] [tmRNA] [long noncoding RNA (lncRNA)] [rRNA genes]

RNA editing

RNA interference (RNAi)

RNA polymerase: [types in eukaryotes]

RNA thermosensors

RNA World

Robertsonian fusions

Rods of human retina

Root pressure

Roots

ROS (reactive oxygen species)

Rotifers, bdelloid

Rough endoplasmic reticulum (RER)

Rous sarcoma virus (RSV)

r-strategists

RUBISCO: see Ribulose bisphosphate carboxylase oxygenase

RU-486: A progesterone antagonist used to prevent or terminate pregnancy. Also called mifepristone. [More] [still more]

S

Saccharomyces cerevisiae (budding yeast): [diploid number] [genome] [aging in]

Salicyclic acid

Salmonella: also [Ames Test] [uptake by cells]

Sanger, F.

Saprophyte: Heterotrophic plant (or fungus) that secures its food by the extracellular digestion of nonliving organic matter.

Sarcoma: A cancer produced by a malignant cell of supporting tissue such as muscle, bone, or cartilage. Compare with carcinoma.

Sarcomere

Sarcopterygians

SARS-CoV-2: Severe acute respiratory syndrome coronavirus 2

Scaphopoda

Scatchard equation

Schistosomiasis: [life cycle of parasite] [how it evades the immune system]

Schwann cell

SCID (Severe combined immunodeficiency): [X-linked SCID] [adenosine deaminase deficiency] [defective V(D)J recombination] [in mice]

Scientific papers: [a case study]

Scientific methods

Scion: Detached part of a plant (e.g., a piece of stem) that is grafted onto another plant. [View]

Sclerenchyma

SCR (S-locus Cysteine-Rich protein)

Scrapie

Screwworm fly

Scrub forest biome

Scurvy: [and collagen]

Secondary immune response

Secondary structure, of proteins

Second messengers

Second-set graft rejection

Secretin

Securins

Sedatives

Seeds

Selection: [natural] [kin] [stabilizing, directional, disruptive] [sexual] [ coefficient (s) ]

Selector gene: Gene that regulates the expression of many other genes. Selector genes encode transcription factors. [Examples]

Selenocysteine

Self-incompatibility in plants

Semen

Semicircular canals

Sense strand: The strand of DNA whose 5' -> 3' sequence is the same (substituting T for U) as that of the corresponding mRNA molecule. (Synthesis of this mRNA uses the antisense strand as a template.) [View] The sense strand is sometimes called the Crick strand.

Sensitive: Able to detect a low level of something. The more sensitive the test, the less likely that it will cause "false negatives"; that is, a failure to detect something that is actually present. Compare specific.

Sensitization

Separins

Sepsis

Sequence: The linear order of amino acids in a polypeptide or nucleotides in a nucleic acid.

Serine

Serine proteases

Serotonin: also known as 5-hydroxytryptamine (5HT) [receptors] [serotonin reuptake inhibitors (SRIs)]

Serpins

Serum

Serum sickness

Severe combined immunodeficiency (SCID): [SCID-X1] [adenosine deaminase deficiency] [defective V(D)J recombination] [in mice]

Sevin

Sewage Treatment

Sex chromosomes

Sex determination: [in honeybees] [environmental]

Sex hormones

Sex organs: [of human female] [of human male]

Sexual reproduction: The production of new individuals following the mixing in a single cell of the genes of two different cells, usually gametes and usually from different parents. [in humans] [in angiosperms] [in gymnosperms] [in mosses] [in ferns] [in bacteria] [in Paramecium]

Sexual selection

Sey ("small eyes") gene

Smallpox

Shade avoidance effect

Shock

Sickle-cell disease

Sievert (Sv)

Signal sequence: A short length of amino acid residues found at the amino terminal of those newly synthesized polypeptides destined to enter the endoplasmic reticulum and, often, removed as they do so. [More] [signal recognition particle (SRP)]

Silencers

Silver Springs ecosystem

SINES (Short Interspersed Elements)

Single nucleotide polymorphisms (SNPs)

Sino-atrial (S-A) node

Sips equation

Sir2 gene

SIV (Simian Immunodeficiency Virus)

Skeleton, human

Skin: hormones of

Skin testing: for immediate hypersensitivities

SLG (S-Locus Glycoprotein)

Slime molds: [cellular] [plasmodial (Myxomycetes)]

SMADs

small eyes (Sey; also Pax6): mouse gene homologous to eyeless in Drosophila and Aniridia in humans. [More]

Smell, the sense of

Smog, photochemical

Smooth muscle

SNAREs

Snow, John

Sodium/potassium ATPase.

sog ("short gastrulation") gene

Soil

Solute: Dissolved substance in a solution.

Solution: Mixture consisting of molecules or ions less than 1 nm in diameter suspended in a liquid medium (water in most biological systems). [schematic of water dissolving crystal of NaCl]

Solvent: Dissolving medium of a solution.

Soma (somatic cells)

Somatic-cell nuclear transfer (SCNT)

Somatic hypermutation (SHM)

Somatostatin

Somite: One of the blocks of mesoderm that develop in a longitudinal series on either side of the notochord in vertebrate embryos.

Sorus

Southern blot

Speciation

Species: Taxonomic category consisting of a group of actually or potentially interbreeding natural populations that ordinarily do not interbreed with other such groups even when there is opportunity to do so. (The singular and plural are spelled alike.) [More]

Specific: Capable of discriminating between two things. A test that discriminates between infection by the human immunodeficiency virus 1 (HIV-1) and HIV-2 is more specific than one that distinguishes only between infection by any HIV and by the simian immunodeficiency virus (SIV). The more specific a test, the fewer the "false positives"; in this example, the less likely that a patient will be diagnosed as HIV-1 positive when he or she is really HIV-2 positive. Some highly-specific tests and reagents are low in sensitivity and vice versa. Compare sensitive.

Specificity, antibody

Spemann, Hans: [egg-tying experiments] [the organizer] [and eye induction]

Spermatogenesis

S phase of cell cycle

Sphenopsids

Spinal cord, human

Spindle checkpoint

Spiracles, insect

Spirochetes

Spliceosomes: [in pre-mRNA processing] [contain a ribozyme]

Sponges (Porifera)

Sporangium: Structure within which asexual spores are produced. [in ferns] [in mosses] [in slime molds]

Spore: Structure, usually unicellular, which serves to disperse the species and/or enable it to survive unfavorable conditions and which can develop into a new individual.

Sporophyte: Diploid, spore-producing stage in the life cycle of a plant. [in angiosperms] [in ferns] [in mosses]

Sporozoans

Squid, hearts of

SRC gene

SRK (S-Receptor Kinase)

SRY: Gene on the Y chromosome that determines maleness. [More]

Stahl, F. W.

Stamen

Standard: [deviation] [error of the mean (S.E.M.)]

Staphylococci

Starch

Stele

Stem cell: A cell that gives rise to both differentiated descendants as well as more stem cells. [general discussion with links to other pages]

Stems, plant

Stereocilia

Sterile-male technique

Steroid: One of many fat-soluble, biologically active compounds whose molecules contain a system of 4 rings made up of 17 carbon atoms.; [cholesterol] [receptors and response elements] [sex hormones] [progesterone] [adrenal hormones]

Sticklebacks: [evidence of sympatric speciation] [mating behavior] [Pitx1 gene]

Stigma

Stimulus: Anything that initiates a response in a cell or organism.

Stolon

Stomach: [physiology]

Stomata: [Discussion] [hormonal control]

STR (Short Tandem Repeat)

Streptococci

Streptococcus pneumoniae: [rough and smooth] [types] [genome]

Striatum

Strigolactones

Stroma, of chloroplast

Suberin

Subspecies (races)

Substance P

Substantia nigra

Substrate: (1) Substance that is acted upon by an enzyme. (2) Base (e.g., soil, rock) upon which an organism lives. Also called the substratum.

Subtilisin

Succession, plant

Sucrose

Sugars

Sulfhydryl group

Sulfur dioxide (SO₂) and acid rain

Superoxide anion

Superoxide dismutase (SOD)

Suprachiasmatic nuclei (SCN)

Sup35p

Survivorship curves

Suspension: Mixture containing solid particles larger than 100 micrometers distributed throughout a liquid. The particles will eventually settle out under the force of gravity.

Symbiosis

Sympathetic nervous system, in humans

Sympatric speciation

Symplast

Symport pumps.

Synapses: [in nervous system] [electrical] [immunological]

Synapsida

Synapsis: Union, side-by-side, of homologous chromosomes early in meiosis I.

Synaptonemal complex (SC)

Syncytium: Mass of cytoplasm containing many nuclei. It can be formed by the fusion of cells (e.g., skeletal muscle fibers) or by the repeated mitosis of nuclei without accompanying cytokinesis (e.g., insect blastula).

Syndecan-1

Syndrome: A collection of symptoms and signs characteristic of a particular disease.

Syntenic: Refers to genes present on the same chromosome. [Examples]

Syphilis

System: Group of organs that perform one or more functions as a unit (e.g., the organs of the digestive system).

Systemic lupus erythematosus (SLE)

Systole

T

T2 virus: [gene mapping] [Hershey-Chase experiment]

T4 virus: [rII locus]

TACO (tryptophan-aspartate coat protein)

Taenia solium

Taiga

TALENs (Transcription Activator-Like Effector Nucleases)

Tanning

TAP = Transporter associated with antigen processing

Tapeworms

Taste, in humans

TATA box

Tatum, E. L.

Taxes

Taxol

Taxonomy: Classification of organisms. [Discussion]

Tay-Sachs disease

TBP (TATA-binding protein)

TCDD (dioxin)

T cell: Lymphocyte that matures within the thymus. [Discussion] [CD4⁺ subset] [CD8⁺ subset] [Helper subsets (Th1, Th2, Tfh, Th17)] [Cytotoxic T Lymphocytes (CTL)] [Regulatory T cells] [Gamma/Delta T cells]

TCR: T-cell receptor for antigen. [More] [gene segments]

Telomerase: [and replicative senescence]

Telomeres

Temperate: [deciduous forest] [rain forest]

Tendon

Teratocarcinoma

Teratogen: A substance that causes birth defects.

Teratoma

Tertiary structure, of protein

Tesla

Test cross: [monohybrid] [dihybrid]

Testes, human

Testosterone

Tetanus: Sustained maximal contraction of a muscle. [More]

Tetracycline antibiotics

Tetracycline response element

Tetrad: (1) The duplicated homologous chromosomes held together by chiasmata prior to anaphase of meiosis I. [View] Each tetrad contains four chromatids. (2) The four products of meiosis kept together like the four spores in the ascus of budding yeast. [View]

Tetrahymena thermophila

Tetraparental mouse

Tetrapods

TFIID (Transcription factor IID)

Thalamus

Thalassemia

THC (delta-9-tetrahydrocannabinol)

Thecodonts

Thelytoky, automictic

Therapsids

Thermoacidophiles

Thiamine (vitamin B₁)

Thick (and thin) filaments of muscle

Thoracic duct

Three-point cross: [in corn (maize)] [in T2 bacteriophage]

Threonine

Threshold: [of response to toxic agents] [of neurons] [of skeletal muscle]

Thrombin

Thrombocytopenic purpura, immune

Thrombomodulin

Thrombopoietin

Thromboxanes (TXs)

Thylakoid: [structure] [and light reactions]

Thymidine kinase

Thymine

Thymus: [function]

Thyroid gland

Thyroid-stimulating hormone (TSH)

Thyrotoxicosis (Graves' disease)

Thyrotropin-releasing hormone (TRH)

Tight Junctions

Timeless (tim) gene

Tinbergen, N.

Tissue: Association of cells bound together by cell walls (plants) or extracellular matrix (animals) that performs particular functions. [plant tissues] [animal tissues]

Tissue Factor (TF)

Tissue plasminogen activator (TPA)

Tissue typing

Titer

Titin

Tocopherol (vitamin E)

Tolerance, immunological

Toll-Like Receptors (TLRs)

Tonus: Sustained, partial contraction of a muscle. [More]

TOR ("target of rapamycin")

Torr: A unit of pressure equal to that exerted by a column of mercury 1 mm high; hence equal to the unit mm Hg.

Total fertility rate (TFR)

Touch, sense of

Toxic shock syndrome

Toxin: Metabolic product (usually a protein) of an organism that is poisonous to another organism.

Toxoid: Toxin treated to destroy its poisonous quality but leaves it capable of stimulating the production of antibodies that will be able to bind to the unaltered toxin. The DTP vaccine contains both diphtheria and tetanus toxoid.

Toxoplasma gondii

TP53: [tumor suppressor gene] [detecting DNA damage]

Tracheal system of insects

Tracheophyte: A plant with a vascular system of xylem and phloem. Includes all plants except mosses and their relatives.

Tranquilizers

Transcription: The synthesis of a sequence of ribonucleotides complementary to the sequence of deoxyribonucleotides in a molecule of DNA. [Discussion]

Transcription factor: A protein needed to initiate the transcription of a gene. Some transcription factors bind to specific sequences of DNA (promoters and enhancers); others bind to each other; many bind both to DNA as well as to other transcription factors.; [general discussion] [selector genes] [glucocorticoid receptor] [jun,fos,myc] [E2F] [TFIIH] [isolating transcription factors by affinity chromatography]

Transcriptome

Transducin

Transduction

Trans fatty acids

Transformation: 1. The modification of the genotype of a cell by introduction of DNA from another source. [Discussion]
2. The conversion of a normal cell into a cancerous one. [Discussion]

Transforming Growth Factor-β

Transgenic: An animal or plant that has been deliberately transformed with a foreign gene and is able to pass that gene on to future generations in its gametes. [making transgenic animals] [making transgenic plants]

Transitions (in DNA)

Translation: The synthesis of a polypeptide in accordance with the genetic information encoded in a molecule of messenger RNA (mRNA).[Discussion]

Translocation: (1) Transfer of a piece of one chromosome to another, nonhomologous, chromosome. [More] [Example: Philadelphia chromosome]; (2) Transport of proteins in (and out) of the endoplasmic reticulum.; (3) Transport of materials, e.g., water and food, from one part of a plant to another.

Transmembrane protein: Protein that passes one or more times through the lipid bilayer of a cell membrane. [color schematic (48K)]

Transmissible spongiform encephalopathies

Transpiration

Transpiration-Pull

Transplantation: [ discussion of organ and tissue transplantation ] [ transplants of hematopoietic stem cells ]

Transport vesicle: Membrane-enclosed structure that shuttles soluble as well as integral membrane proteins to various destinations within the cell. [More]

Transposons

Transversions (in DNA)

Trematoda

Tricarboxylic acid cycle (TCA)

Tricyclic antidepressants

Triglyceride

Trihalomethanes (THMs) (by-products of water chlorination)

Trilinolein

Trinucleotide repeats

Trisomy 21

Tristearin

Trochophore larva

Trophic level

Trophoblast

Tropical rain forest biome

Tropisms

Troponin and Tropomyosin

TRPV receptors

Trypanosomiasis (African sleeping sickness): [how the parasite evades the immune response]

Trypsin

Tryptophan: [structure] [repressor]

TSH: Thyroid-stimulating hormone

T system

Tuberculosis (TB)

Tubular secretion

Tubulin

Tularemia

Tumor-infiltrating lymphocytes (TIL)

Tumor necrosis factors (TNF): [and inflammation] [and apoptosis] [TNF-β (lymphotoxin)] [TNF-α receptors]

Tumor Suppressor Genes

Tundra biome

Tunicata (Urochordata)

Turbellaria

Turgor: [in guard cells of leaf]

Turner syndrome

Two-hybrid system

Tyrosine

Tyrosine kinases

U

Ubiquitin

UCP1 (Uncoupling Protein 1)

Ultrabithorax (Ubx)

Ultraviolet: [radiation] [and ozone shield] [vision]

Units, scientific]

Uracil

Ure2p

Urea cycle

Uric acid

Urine, formation of

Urochordata (Tunicata)

Urticaria (hives)

Utriculus

V

V2 receptors

Vaccine: Preparation of dead or weakened pathogens, or their products, which when introduced into the body, stimulates the production of protective T cells and/or antibodies without causing the disease. [Discussion] [flu vaccines] [against AIDS] [against smallpox]

Vacuoles, in plant cells

Vagus nerves: [effect on the heart]

Valence: Number of electrons gained, lost, or shared by an atom in bonding to one or more other atoms. [Discussion] [types of chemical bonds between atoms]

Valine

Variable number of tandem repeats (VNTRs)

Variant surface glycoprotein (VSG) of trypanosomes

Variation, continuous

Variola virus: Variolation

Vascular: Containing vessels that conduct liquid.

Vasectomy

Vasopressin (also known as arginine vasopressin, the antidiuretic hormone (ADH), and vasotocin). It is a peptide hormone/neurotransmitter found in mammals. In non-mammalian vertebrates (e.g., birds, fish), the homologous product is called vasotocin. Because of their homology, it has been proposed (2021) the vasotocin (VT) be used for the mammalian peptide as well.

V(D)J Joining

Vector: (1) An animal (e.g., an insect) that transmits a parasite. [Example] Reducing the population of a vector is often a good way to lower the incidence of the disease it transmits. (2) In genetic engineering, a virus or plasmid that carries a molecule of recombinant DNA into a cell, thus transforming it. [retroviral vectors] [adeno-associated virus (AAV) as a vector]

VegT

Venter, J. C.: [minimal genome] [synthetic genome]

Ventral tegmental area (VTA)

Vernalization

Vertebrate: Any backboned animal. Includes fishes, amphibians, reptiles, birds, and mammals. [Discussion] [comparative kidney structure and function] [vertebrate lungs] [vertebrate hearts] [vertebrate brains]

Vestigial: Term applied to a degenerate or incompletely developed structure which was more fully developed at an earlier stage of the organism and/or its ancestors.

Vibrio cholerae

Viking missions to Mars

Villi

Vimentins

Virion

Viroids

Viruses: [general discussion] [latent] [RNA viruses]

Virusoids

Viscera: Organs in the body cavity.

Vision: [in humans] [processing visual information] [in insects] [ultraviolet]

Vitamins: [in human nutrition] [Recommended Dietary Allowances (RDAs)]

Vitamin K

Vitreous body

Viviparous: Having embryos that develop to adult form within the mother's body while securing most of their nourishment from the mother's tissues rather than from the yolk of the egg.

Volvox

Vomeronasal organ (VNO)

von Frisch, K.

von Willebrand Factor (vWF)

W

Waldenström's macroglobulinemia (also known as lymphoplasmacytic lymphoma)

Water: [properties] [transport in plants]

Water molds (Oomycetes)

Watson, J. D.

Weismann: Continuity of Germplasm

Went, F. W.

Werner's syndrome

Western blot

Wiesel, T. N.

Wilms' tumor

wingless (wg) gene

Wnt signaling

Wolbachia

X

X chromosome: [X-chromosome inactivation (XCI)] [role of XIST locus]

Xenarthra

Xenopus laevis, the South African clawed frog.

Xenotransplantation: Graft of an organ or tissue between members of different species. [More]

Xeroderma pigmentosum (XP)

XIST

X-linkage

X-linked adrenoleukodystrophy (X-ALD)

X-linked agammaglobulinemia

X-linked SCID

Xylem: [ transport in ] [in roots]

Y

Y chromosome

Yeast: A unicellular fungus. One species, the budding yeast Saccharomyces cerevisiae, is used in brewing and baking because of the ease with which it ferments carbohydrates to ethyl alcohol and carbon dioxide.