Question

Describe how the specificity of certain trans-acting factors only binding certain cis-acting factors is achieved.

Answer 1

Trans- acting factors are proteins which bind to the cis acting factors to control gene expression . Trans acting factor bind to RNA polymerase . This is to stabilise the initiation complex . These are required for transcriptional initiation and are called the positive regulators of gene expression . Trans- acting factors help to assemble the complete transcriptional machinery onto the various cis - acting elements . These factors co- ordinate with one another to govern a coordinated expression pattern of the gene . To completely on or off the transcription of gene ,trans acting factors are required . They bind to cis regulatory regions such as promoter , enhancers and silencers to exert their activation or repression function .