The necessary components for gene expression are often described as either cis -
ID: 142650 • Letter: T
Question
The necessary components for gene expression are often described as either cis-acting elements (“acting from the same molecule”) or trans-acting factors (“acting from a different molecule”). Cis-acting elements are typically sequences that are required for expression. Trans-acting factors are typically proteins that recognize and bind cis-acting sequences to control or facilitate gene expression. For each of the cis-acting elements below, Promotor and Start Codon,list a trans-acting factor involved in its recognition and describe the factor’s normal function
Explanation / Answer
Cis-acting elements are nucleic acid sequence elements. They act on the same sequence. They cannot be complemented. They do not code for a diffusible product.
Ex: Promoter, operator, enhancer, silencer, start and stop codons.
Trans-acting factors are diffusible products such as RNA or protein. They act in trans. They can be complemented.
Ex: RNA and protein
The promoter is recognized by RNA polymerase.
Enhancer is recognized by activator proteins
Silencer is recognized ba y repressor.
Translation start and stop codons are recognized by ribosomes (Initian and release factors).
Transcription start and stop codons are recognized by RNA polymerase (Initian and termination factors).