Glossary - Genetic (T)

Tandem repeat sequences

Multiple copies of the same base sequence on a chromosome; used as markers in physical mapping.
See also: physical map

Targeted mutagenesis

Deliberate change in the genetic structure directed at a specific site on the chromosome. Used in research to determine the targeted region's function.
See also: mutation, polymorphism

Technology transfer

The process of transferring scientific findings from research laboratories to the commercial sector.

Telomerase

The enzyme that directs the replication of telomeres.

Telomere

The end of a chromosome. This specialized structure is involved in the replication and stability of linear DNA molecules.
See also: DNA replication

Teratogenic

Substances such as chemicals or radiation that cause abnormal development of a embryo.
See also: mutatgen

Thymine (T)

A nitrogenous base, one member of the base pair AT (adenine-thymine).
See also: base pair, nucleotide

Toxicogenomics

The study of how genomes respond to environmental stressors or toxicants. Combines genome-wide mRNA expression profiling with protein expression patterns using bioinformatics to understand the role of gene-environment interactions in disease and dysfunction.

Transcription

The synthesis of an RNA copy from a sequence of DNA (a gene); the first step in gene expression.
See also: translation

Transcription factor

A protein that binds to regulatory regions and helps control gene expression.

Transcriptome

The full complement of activated genes, mRNAs, or transcripts in a particular tissue at a particular time

Transfection

The introduction of foreign DNA into a host cell.
See also: cloning vector, gene therapy

Transfer RNA (tRNA)

A class of RNA having structures with triplet nucleotide sequences that are complementary to the triplet nucleotide coding sequences of mRNA. The role of tRNAs in protein synthesis is to bond with amino acids and transfer them to the ribosomes, where proteins are assembled according to the genetic code carried by mRNA.

Transformation

A process by which the genetic material carried by an individual cell is altered by incorporation of exogenous DNA into its genome.

Transgenic

An experimentally produced organism in which DNA has been artificially introduced and incorporated into the organism's germ line.
See also: cell, DNA, gene, nucleus, germ line

Translation

The process in which the genetic code carried by mRNA directs the synthesis of proteins from amino acids.
See also: transcription

Translocation

A mutation in which a large segment of one chromosome breaks off and attaches to another chromosome.
See also: mutation

Transposable element

A class of DNA sequences that can move from one chromosomal site to another.

Trisomy

Possessing three copies of a particular chromosome instead of the normal two copies.
See also: cell, gene, gene expression, chromosome