biology-dictionary_11-06-2009

Stem cells The common, self-regenerating cells in the marrow of long bones that give rise, by differentiation and division, to r ...

Stolons An above ground prostrate stem that develops roots and leaves at nodes along its length, e.g. couch grass. Stoma A micro ...

Stroma The fluid of the chloroplast surrounding the thylakoid membrane; involved in the synthesis of organic molecules from carb ...

Submetacentric Having the centromere near the center but not in the middle, so that one arm is shorter than the other. Suborgane ...

Summation A phenomenon of neural integration in which the membrane potential of the postsynaptic cell in a chemical synapse is d ...

Sympathetic division One of two divisions of the autonomic nervous system of vertebrates; generally increases energy expenditure ...

Synthesis The formation of a more complex substance from simpler ones. Synthesis phase In the cell cycle, the phase in which the ...

Tannins A yellowish compound found in many plants, such as tea and grapes, and used in tanning and dyeing also called tannic aci ...

Temperate deciduous forest A biome located throughout midlatitude regions where there is sufficient moisture to support the grow ...

Terpenoid compounds Any compound with an isoprenoid structure similar to that of the terpene hydrocarbons. Territory An area or ...

Thalamus One of two integrating centers of the vertebrate forebrain. Neurons with cell bodies in the thalamus relay neural input ...

Thorns A modified branch in the form of a sharp, woody spine. Threatened species Species that are likely to become endangered in ...

Tight junction A type of intercellular junction in animal cells that prevents the leakage of material between cells. Tissues An ...

Tract A group or bundle of nerve fibers with accompanying connective tissue, located within the central nervous system. Transcri ...

Transposon A transposable genetic element; a mobile segment of DNA that serves as an agent of genetic change. Transverse connect ...

Tropical rain forest The most complex of all communities, located near the equator where rainfall is abundant; harbors more spec ...

Tunicates Any of various sedentary tunicates of the class Ascidiacea, having a transparent sac-shaped body with two siphons. Als ...

Ultrastructural View The detailed structure of a biological specimen, such as a cell, tissue, or organ, that can be observed onl ...

Urine The liquid waste filtered from the blood by the kidney and stored in the bladder pending elimination through the urethra. ...

Van der Waals interactions Weak attractions between molecules or parts of molecules that are brought about by localized charge f ...