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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

S

Saccharomyces cerevisiae (budding yeast)
[diploid number] [genome] [aging in]
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
Scaphopoda
Scatchard equation
Schistosomiasis
[life cycle of parasite] [how it evades the immune system]
Schwann cell
SCID (Severe combined immunodeficiency)
[SCID-X1] [adenosine deaminase deficiency] [defective V(D)J recombination] [in mice]
Scientific methods
[a case study]
Scientific papers
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)
[X-linked SCID] [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
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]
Smallpox
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
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