Question

Compare and contrast post-transcriptional controls in eukaryotes vs prokaryotes.

Answer 1

Both prokaryotic and eukaryotic cells have mechanism to regulate DNA and RNA.The process prevents cells from expending energy on unnecessary metabolic processes.All of the cells of the organism contain the same genes,but they don't necessarily use the same genes .Eukaryotic cells employ a number of control mechanisms to ensure that the genes are expressed only when they are needed.There are several control points during gene expression .Pretranscriptional control includes DNA methylation andhistone acetylation.Transcriptional controls involve transcription factors,which are necessary in order for transcription to occur.Enhancers are sequences of DNA that are up to thousands of nucleotides away from the promoter.Transcription factors called activators bind to enhancers and help from the transcription intiation complex.Transcription level controls iinclude transcription factors and enhancers.Gene expression can also be controlled at the level of post-transcription,pre-translation,translation,post-translation.After transcription yields mRNA molecule the cell still has many other opportunities to regulate protein processing..In post transcriptional control RNA processing involves the addition of a cap and a tail to a new mRNA transcript.This addition prevents nuclease enzymes present in the cytoplasm from hydrolyzing the transcript.One of the hypothesis is that to build up of the protein product can wear down the protective additions,enabling the break down of the mRNA transcript and preventing translation.In prokaryotes ,mRNA transcription requires a promoter.The promoter serves as recogination site for RNA polymerase .RNA polymerase binds to the promoter and then procceds to direct transcription of the mRNA molecule..The lac operon regulates mRNA transcription of enzymes responsible for digesting lactose.mRNA degradation in prokaryotes is challenging because most mRNA undergo rapid exponential decay. Prokaryotic mRNA differe in their suspectability to degradation by endonuclease and exonuclease possibily because of variation in sequencing and structure.Inspite of numerous studies still degradation of mRNA degradation is still largely unknown