Indicate whether each of the following, when active, tends to activate (A) or inactivate (I) M-Cdks. Your answer would be a four-letter string composed of letters A and I only, e.g. IIAI.
( ) M-Cdk
( ) Cdc20-APC/C
( ) Cdh1-APC/C
( ) Sic1

Question

Indicate whether each of the following, when active, tends to activate (A) or inactivate (I) M-Cdks. Your answer would be a four-letter string composed of letters A and I only, e.g. IIAI.
( )	M-Cdk
( )	Cdc20-APC/C
( )	Cdh1-APC/C
( )	Sic1

Quizplus · Accepted Answer

Both Cdc20-APC/C and Cdh1-APC/C target M-cyclins for degradation. M-Cdk, in turn, activates the former and inactivates the latter. Sic1 in budding yeast is an example of a CKI that also inhibits M-Cdks. M-Cdk activates the expression of M-cyclin genes in a positive feedback loop, although its activity is also regulated by negative feedback, for example through Cdc20-APC/C mentioned above.

Indicate Whether Each of the Following, When Active, Tends to Activate