You have identified a gene with three exons and two introns. the exons are 200bp, 600bp, and 100bp in length consecutively, while the introns are 500bp and 400bp in length. the normal rna produced by this gene is approximately 900bp in length. however in neurons you identify an rna made from this gene that is 1400bp in length, what form of alternative splicing most likely occurred?
a. exon skipping
b. mutually exculsive exons
c. alternative 5' donor or 3' acceptor sites
d. intron retention

The correct answer is option d. "Intron retention".

Explanation:

Intron retention is an alternative splicing modification that results in RNA having nucleotide sequences that would normally be removed as introns during RNA maturation. If a normal RNA is approximately 900 bp, and the same gene produces another RNA of 1400 bp, the latter longer version of RNA would most likely occurred as a result of intron retention. Intron retention is usually overlooked as a mechanism to reduce gene expression, but nowadays it has been recognized for its role in normal physiology and the onset of diseases.

complete the square on the right side of the equation;

-5(x + 0)^2 + 15

answer: d. y = -x^2 + 15