Transcriptional Regulation
Transcription Regulation constitutes a major component of biological activities in the cell. A key function of transcriptional activity is the control of gene expression necessary for the maintenance of a cellular state. In metazoans, all cell types, except mature germ cells, contain the same genetic information within the species. Yet, each cell type expresses a unique subset of all genes encoded. This is because each type of cell expresses different genes, a mechanism known as "differential gene expression."
Differential Gene Expression
Differential gene expression can be controlled at many levels. Transcription occurs at the first stage of expression. Coding and non-coding genes contain promoter and enhancer sequences that are bound by transcription activators and repressors, known as transcription factors (TFs). The levels and activities of TF's determine the extent of transcription.
Regulation of gene expression refers to the control of the amount and the timing of appearance of the functional product of a gene. Control of gene expression is vital to allow a cell to produce the gene products it needs when it needs them; this, in turn, provides cells with the flexibility to adapt to a variable environment, external signals, damage to the cell, etc. Gene expression in organisms is carefully regulated to allow them to adapt to variable conditions and, most importantly, to prevent wasteful overproduction of unneeded proteins, which would make the organism not productive.
Why Do Organisms Regulate Expression of Their Genes?
Organisms regulate expression of their genes to achieve developmental changes, cellular specialization, and adaptation to a new environment. The expression of genetic information in a given cell or organism is neither random nor fully pre-programmed. The information in an organism's genome must be regulated in an orderly fashion during development and, yet, must be available to direct the organism's responses to changes in internal and external conditions. Thus, every step of the pathway, from gene expression to protein synthesis, localization, and degradation, can be controlled to maximize the cell's survivability and efficiency.
