25
Dec
2009
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Glossary

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

T

T
(1) In DNA, thymine. (2) In proteins, threonine.
tandem duplication
A duplication, the products of which reside in close proximity to each other on the chromosome.
taxon (plural, taxa)
A taxonomic group of any rank (e.g., species, genus, kingdom) to which individual organisms are assigned.
taxonomy (classification)
The principles and procedures according to which species are named and assigned to taxonomic groups.
TBR
Tree-Bisection Reconnection.
terminal node
The graphical representation of an extant taxon in a phylogenetic tree.
termination codon (nonsense codon, stop)
A codon for which no normal tRNA exists, the presence of which terminates the process of translation. The three termination codons in the universal genetic code are UAG, UAA, and UGA.
tertiary structure
In proteins and nucleic acids, the three-dimensional structure of the molecule brought about by its folding upon itself.
thermal stability
The degree of resistance against denaturation or melting.
topology
The branching pattern of a phylogenetic tree.
transcription
The synthesis of an RNA molecule on a DNA template.
transcription-initiation site
(see cap site)
transduction
The transfer of host genetic information from one cell to another by means of a virus.
transfer RNA (tRNA)
A small ribonucleic acid molecule that contains an anticodon, a binding site for a specific amino acid, and recognition sites for interaction with the ribosome and the enzyme that links it to its specific amino acid.
transition
The substitution of a purine for a purine or a pyrimidine for a pyrimidine.
translation (decoding)
The derivation of the amino acid sequence of a polypeptide from the sequence of an mRNA molecule via tRNA intermediates which occurs in association with a ribosome.
transposable element (mobile element)
A sequence that can move about in the genome of an organism.
transposition
The movement of genetic material from one genomic location to another.
transposon
A transposable element carrying additional genes beside those encoding the transposition functions.
transversion
The substitution of a purine for a pyrimidine or vice versa.
trisomy
The presence of three copies of a chromosome in an otherwise diploid cell.
tRNA
(see transfer RNA)
twofold degenerate site
A nucleotide site in the coding region at which one of the three possible nucleotide changes is synonymous and the other two are nonsynonymous.