Which of the following is an example of post-transcriptional control of gene expression? a. gene amplification contributing to cancerb. the removal of introns and alternative splicing of exonsc. the addition of methyl groups to cytosine bases of dnad. the binding of transcription factors to a promotere. the folding of dna to form heterochromatin

The correct answer is: b. the removal of introns and alternative splicing of exons

Post-transcriptional regulation includes processes of regulation between transcription and translation such as RNA splicing, capping, addition of poly-A tail,  RNA editing.

RNA splicing represents the process of RNA processing in which newly synthesized pre-mRNA transcript is converted into a mature mRNA. This process occurs only in eukaryotic organism and includes the removal of introns and joining together the exons. RNA splicing might occur during or immediately after transcription and it is performed by spliceosome (complex of small nuclear ribonucleo proteins).

Alternative splicing is a regulated process in which a single gene can code for multiple proteins because particular exons of a gene may be included within or excluded from the final mRNA.

answer: the blood-brain barrier is a layer of specialized membranes and cell processes designed to keep undesirable substances from passing from the bloodstream into the precious tissues of the brain. while the blood-brain barrier does keep most bad things out of the central nervous system, it is not impermeable.

explanation: