The gene encoding Hes7 in mouse contains three introns. Any or all of these introns can be deleted to alter the delay associated with transcription and splicing of Hes7 mRNA. As a result of such deletions, either the oscillation frequency of this gene's expression can change (result 1) or the oscillatory behavior can disappear altogether (result 2). One of these two results is obtained when only one intron is deleted from the gene, while the other result is obtained when all three introns are removed. Would you expect the oscillation frequency to increase or decrease if result 1 is obtained? Which result (1 or 2) would you expect to observe when all three introns are deleted?
A) Increase; result 1
B) Increase; result 2
C) Decrease; result 1
D) Decrease; result 2

Question

Quizplus · Accepted Answer

Deleting only one intron shortens the gestation delay for the mRNA only slightly, leading to an overall shorter feedback delay and therefore higher oscillation frequency. Deleting all three introns shortens the delay to such an extent that a sustained oscillation is no longer supported.

The Gene Encoding Hes7 in Mouse Contains Three Introns