Which of the following is an example of post-transcriptional control of gene expression?
a) the addition of methyl groups to cytosine bases of dna
b) the binding of transcription factors to a promoter
c) the removal of introns and alternative splicing of exons
d) gene amplification contributing to cancer
e) the folding of dna to form heterochromatin

The correct option is C.

Post transcriptional control of gene expression refers to the process by which primary transcripts of RNA, which are formed in the nucleus of eukaryotic cells are converted into mature RNA. The process occurs after transcription and prior to translation.

In eukaryotic cells generally, gene expression is typically controlled at the transcription level. The process of post transcriptional occurs in two stages; the first stage is called RNA splicing stage and the second stage involves the control of RNA stability.

RNA SPLICING Stage: The primary RNA transcript is made up of two different regions, the exons regions, which code for proteins and the introns regions, which do not code for any protein. At the RNA splicing stage, the introns are spliced and removed from the RNA strand. This is the reason why option C is correct.

The second stage involves the addition of protective caps to the two ends of the RNA strands. These caps prevent the degradation of the RNA strand, thus, making it stable.

After this process, the mature RNA that has just been formed leaves the nucleus and move to the cytoplasm area of the cell, ready to carry out the process of protein translation.  

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