In order to ensure that chromosomal DNA is replicated once and only once in each
ID: 20859 • Letter: I
Question
In order to ensure that chromosomal DNA is replicated once and only once in each cell cycle,eukaryotic cells have evolved a complex system of control involving Cdc6, a pre-replicative complex, Origin
recognition complex and S-Cdk.
A. You activate the promoter of Cdc6 so that gene expression and protein production also occurs in
mid-S phase. What do you predict will happen during the cell cycle?
B. What if Cdc6 always behaved as if it were phosphorylated?
Explanation / Answer
Regulation of Cdc6p is one of several redundant mechanisms that prevent re-replication of the DNA in eukaryotic cells. Two states can be distinguished. In the first state (during G1 phase) Cdk1-activity is low, Cdc6p can accumulate, hence the pre-RC can be formed but not activated. In the second state Cdk1-activity is high, Cdc6p becomes inactivated, hence the pre-RC is activated but not formed. a>in this case more than one dna replications occurs in one cell cycle leading to formation of tumors. b>cdc6 will be deactivated if it was phosphorylated the The inactivated Cdc6p is then targeted for degradation by SCFCDC4-dependent ubiquitinylation and afterwards degraded by the proteosome. pre-RC is activated but not formed.
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.