Promoter A segment of DNA that acts as a controlling element in the expression of a gene . It marks the site of initiation of gene transcription . Protein A molecule composed of amino acid s linked together in a particular order specified by a gene 's DNA sequence. Separation becomes necessary when genes are being transcribed or when DNA is replicated prior to cell division. In multicellular organisms, a cell of the soma, or tissues, as opposed to a cell of the germ line, or sex cell.
Transcription see gene transcription .
Translation see gene translation . A gene that helps prevent the transformation of normal cells into cancer cells. When both copies of a tumor-suppressor gene are mutated in a cell, however, the lack of suppression may lead to the development of cancer. X-linked Refers to any gene found on the X chromosome or traits determined by such genes. Refers also to the specific mode of inheritance of such genes.