Question

Define the terms cis-acting DNA sequences and trans-acting proteins.

Answer 1

The term trans comes from the Latin root “trans,”meaning “across from.”

In molecular biology, a cis-acting (or cis-regulatory) element refers to a region of the chromosomal DNA that regulates the transcription or expression of a gene that is on the same chromosome..

In regulation, a trans-acting element is usually a DNA sequence that contains a gene. This gene codes for a protein (or microRNA or other diffusible molecule) that will be used in the regulation of another target gene.

Cis-acting elements, on the other hand, do not code for protein or RNA.

Cis-regulatory elements are often binding sites for one or moretrans-acting factors.

cis-regulatory elements are present on the same molecule of DNA as the gene they regulate whereas trans-regulatory elements can regulate genes distant from the gene from which they were transcribed.

The transcription initiation complex is composed of  promoter sequences and DNA binding proteins..

These two components of transcription are normally described as cis-acting elements and trans-acting factors. These genes have sequence modules in common that control the coordinate regulation.