Glossary – T

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T

T cells
T cells are a subtype of leukocytes and as such are part of the immune system. They are involved in cell-mediated immunity and recognize their target antigen via receptors when the antigen is presented by MHC molecules. T cells are divided into different subsets with special functions, such as helper, cytotoxic (CTL), regulatory or natural killer T cells.

tet on/off
Tet on/off is a method for inducing the expression of a gene. The gene can be turned on or off by the addition of the antibiotic tetracycline (Tet).

tetraploid
A tetraploid is a cell or complete organism that carries four chromosome sets instead of two.

transfection
A technique for transferring DNA, RNA or protein into cells.

transcription
Process producing a complementary RNA copy of a DNA sequence. If this RNA copy is derived from a protein-coding gene, the RNA is called messenger RNA.

transduction
DNA transfer into a cell by a virus. A natural virus transfers its complete genome into a target cell. Therefore, put more accurately, transduction means genome transfer, in contrast to transfection which means gene transfer.

transformation
Transformation is DNA uptake by a bacterial cell, which occurs both naturally and is carried out in a laboratory setting using specially developed techniques. In mammalian cells, transformation is the process of malignant degeneration, as transformed cells form tumors in mammals.

transgenic animals
A transgenic animal carries foreign DNA that has been stably inserted into the genome.

translation
Process of generating a protein from mRNA (see transcription).

transposon
A naturally occurring “jumping gene”, or more specifically, a DNA sequence that is either copied or cut at one position of the genome and pasted at another position. Transposons can be used for stable gene transfer.

tumor
A tumor is not synonymous with cancer. It is a bulk of cells derived by uncontrolled growth of transformed cells surrounded by normal tissue. A tumor can be malignant or benign; it may or may not have a cancerous potential.