Question

1. What is meant by describing a protein function as a genetic activator or repressor? Give an example of a class of proteins that can be described as genetic activators and how they work? (500 words)

Answer 1

When it comes to the term a repressor and an activator it means the proteins have entirely two different function.These proteins acts as repressing factor or as an activating factor.

In the molecular genetics what a  repressor do is it is a protein that bind to DNA or RNA  that inhibits the expression of one or more genes by binding to the operator or associated silencers. A nd this DNA-binding repressor blocks the attachment of RNA polymerase to the promoter,and thus preventing transcription of the genes into messenger RNA.

Now when a protein acts as an activator it when bound to its DNA binding site, it increases transcription of the operon (e.g., by helping RNA polymerase bind to the promoter) so activates or increses the transcription so the protei either blocks or activates the transcription thus obtain the term.

The example of genetic activators include

The catabolite activator protein (CAP; also known as cAMP receptor protein, CRP) it activates transcription at the lac operon of the bacterium Escherichia coli. Another one adenosine monophosphate (cAMP) is produced during the time of glucose starvation, and then it will bind to CAP, and causes a conformational change that allows CAP to bind to a DNA site located adjacent to the lac promoter. CAP then makes a direct protein–protein interaction with RNA polymerase that recruits RNA polymerase to the lac promoter.These are the few examples of the genetic activators .cAMP protein is the most prominent one here.