Some feed-forward motifs are capable of generating a brief pulse of gene activation in response to a sustained input signal: in such motifs, the signal activates an activator (A) and a repressor (R), both of which control the expression of the same gene. The quantitative output of the gene depends in part on the relative affinities of A and R for binding to the cis-regulatory sequences of the target gene. Under which of the following conditions is a brief pulse of gene activation observed in response to a sustained input signal? KA and KR are the association constants for A and R, respectively. A) KA = KR B) KA KR D) KAKR 1

Question

Some feed-forward motifs are capable of generating a brief pulse of gene activation in response to a sustained input signal: in such motifs, the signal activates an activator (A) and a repressor (R), both of which control the expression of the same gene. The quantitative output of the gene depends in part on the relative affinities of A and R for binding to the cis-regulatory sequences of the target gene. Under which of the following conditions is a brief pulse of gene activation observed in response to a sustained input signal? KA and KR are the association constants for A and R, respectively. A) KA = KR B) KA << KR C) KA >> KR D) KAKR > 1

Quizplus · Accepted Answer

With a high binding affinity, the slow repressor eventually represses gene expression even in the presence of a sustained input signal.

Some Feed-Forward Motifs Are Capable of Generating a Brief Pulse