Encyclopedia of Biology

tetrahydrofolate Reduced FOLATE derivative that contains additional hydrogen atoms in positions 5, 6, 7,and 8. Tetrahydrofolates ...

Returning to Sweden in 1935, he worked at the Karolinska Institute, and in 1936 he was appointed head of the newly established b ...

This process allows T cells to develop self-tolerance (distinguishing self from nonself). While developing in the thymus gland, ...

trace elements Elements required for physiological functions in very small amounts that vary for different organisms. Included a ...

transcription factor The regulatory protein that binds to DNA and stimulates the transcription of genes. transduction (1) The tr ...

trapping The interception of a reactive molecule or reaction intermediate so that it is removed from the system or converted int ...

troop Agroup of lemurs, monkeys, apes, or other primates. trophallaxis The mutual exchange of alimentary liq- uid among colony m ...

tuberculosis(TB) A contagious bacterial infection caused by bacteria that are members of the Mycobac- teriumgenus, usually by My ...

a single fertilized egg that splits in two and creates two genetic replicas, while fraternal twins develop from separate eggs an ...

ubiquitous Existing or having presence everywhere at the same time. For example, ribonuclease, an enzyme that degrades RNA, is u ...

therefore the more kinks, the more beneficial it is to human health. The kinks, by completely changing the physical and chemical ...

uterus A pear-shaped hollow female reproductive organ in the pelvis area, at the top of the vagina, where eggs are fertilized an ...

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337 vaccination Injection of a killed or weakened infec- tious organism (virus, bacterium) in order to prevent the disease. Vacc ...

vascular cambium A secondary meristem, i.e., a thin layer of undifferentiated plant cells that divide indefinitely, which gives ...

ejaculatory duct and urethra. The tube connects the testes with the urethra and has thick muscles to move the sperm down the tra ...

includes fish, amphibians, reptiles, birds, and mam- mals; a member of the phylum Chordata. Three subphyla exist: Urochordata (s ...

lesion, or blister containing a clear watery fluid; a cavi- ty or sac, especially one filled with fluid. Anatomy refers to the u ...

soul or spirit, that must be added to the equation that brings us life as we know it. This was one of the central interests of s ...

(niacin-vitamin B 3 ), vitamin B 6 (pyridoxine), vitamin B 12 (cobalamin), pantothenic acid (vitamin B 5 ), pyri- doxal (vitamin ...