Mechanisms for Controlling Eukarytotic Gene Expression.

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Mechanisms for Controlling Eukarytotic Gene Expression.

Every cell in a multicellular organism (eukaryote) has the potential to express every gene in the genotype. However for proper development and functioning certain cells must express only certain genes at appropriate times. Therefore the expression of such genes must be tightly regulated. Eukaryotes find many ways of controlling gene expression but they fall mainly into these three categories: transcription, RNA processing and Translation. In some cases regulation can depend on the DNA itself, the position of genes on a chromosome and their respective frequency. In other cases the proteins that bind to the DNA can make genes more or less available for transcription. The processing and transcription of the pre-mRNA can be regulated. Transport of the pre-mRNA into the cytoplasm, its translation into protein can be controlled. Finally, once the protein itself is made, its structure can be modified, thereby affecting its activity. All of these methods for control will be explained in turn according to the three categories explained above.

Transcriptional Control

Transcription is the process of creating a complementary strand of mRNA (messenger RNA) from the double stranded DNA precursor. This mRNA is the intermediate between the DNA and