Which of the following genes is most likely regulated at the posttranscriptional

Question

Which of the following genes is most likely regulated at the posttranscriptional level?

a. Gene A, which shows a strong positive correlation between the amount of mRNA produced and the amount of protein produced

b. Gene B, which shows no clear correlation between the amount of mRNA produced and the amount of protein produced

c. Gene C, which lies near the heterochromatin

d. Gene D, which has more than the typical number of CpG islands

e. Gene E, which has fewer than the typical number of CpG islands

Explanation / Answer

b. Gene B, which shows no clear correlation between the amount of mRNA produced an the amount of protein produced.

Justification:

-> not (a) because the number of transcripts and amount of protein are correlated i.e. if one increases so does the other and vice versa. hence there is no likeliness of any regulation happening between transcription and translation i.e. post-transcriptional.

-> (b) because ideally and increase or decrease in transcipt level should have resuted in a similar change in the protein levels. A failure in this indicates that some changes are occuring post-transcriptionally eg. changes in mRNA stability, interference by miRNAs, etc.

-> not (c) because heterochromatin is a state of DNA. hence this would regulate/hinder the transciptional process itself rather than creating changes at the post-transcriptional levels.

-> not (d) and (e) because CpG islands are regions of DNA having high number of cytosine-phosphate-guanine. They are potential sites for methylation at 5th carbon of cytosine. hypermethylation = low transcription and hypomethylation = high transcition.  hence this would regulate/hinder the transciptional process itself rather than creating changes at the post-transcriptional levels.

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