Question

Explain levels of regulation of gene expression, including transcriptional and post-transcriptional regulation.

Answer 1

Regulation of gene expression determined which gene to be express.

EXAMPLE-the cell of stomach and eye both contain gene to make HCL but eye cell does not produce HCL and stomach cell does. this is because of gene regulation. The HCL coding sequence is not express in eye cell and is express and functional in stomach cell.

Gene regulation can occur at various level or stages.below mention are the various stages in which gene regulation can occur-

LEVELS OF GENE REGULATION

-chromatin domains

-transcription

-post transcription modification

-RNA transportaion

-translation

-mRNA degradation

Transcriptional regulation control gene expression at DNA level , at the time of mRNA synthesis. Transcriptions of genes can be regulated by various factors located inside and outside the cell , which help the cell to adopted according to its environment . Most genes are regulated by binding by a REGULATORY GENE ( specific gene sequence to which regulatory protein bind). regulatory gene can be located adjacent or few base pair away to the promoter.

The genes which increase the rate of transcription are called Activators .

The genes which decrease the rate of transcription are called Repressor .

in eukaryotic cell- proteins which bind with the regulatory gene does not control the rate by itself and produce co enzymes to influlence the rate of transcription. CO-ACTIVATORS help in increase the rate of transcription .

CO-REPRESSOR help in decrease the rate of transcription.

Post transcriptional regulation is controlling gene expression at RNA level, that is between transcription and translation . If the gene regulation is not done at transcription level ,the newly form mRNA is precursor mRNA which contain both introns (non coding regions) and  exons(coding region)

In eukaryotic cell splicing is carried out with the help of catalyzing reaction by spliceosome to remove introns and from mature mRNA.

After RNA splicing  control of RNA stability is done by providing mRNA two protective cap before leaving tne nucleus. 5'cap placeon the 5' end of RNA compose of GTP.

poly-A tail on 3' end of RNA compose of series of adenine nucleotide.