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- 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]