Review Questions for Cell Cycle Regulation
Besides the questions at the cell cycle tutorial
Here are some additional review questions for
Cell Cycle Regulation in Eukaryotes.
1) Labile cell cycle regulatory proteins whose concentration oscillates in
correlation with the cell cycle are called ________________
2) Progression through the cell cycle is regulated by the activities of a
family of protein kinases known as ____________________________.
3) What is the general enzyme activity for a kinase? ______________-
4) To ensure that undamaged DNA is all replicated once and once only, and
that one copy of each chromosome goes to each daughter cell, the cell
cycle has evolved as a sequence of checkpoints that arrest progress until
each critical step has been completed. Where are these checkpoints?
5) What protein is responsible for monitoring DNA damage and blocking of
cell cycle progress if DNA repair fails? _______________________
6) p21 is an example of a CDK inhibitor. What is its function in cell cycle
7) Here is a partial list of targets of cyclin/CDK targets. Why might each
be targeted by a cyclin/CDK complex?
G1 p53, pRb - cell proliferation regulators
S DNA polymerase,
M origin complex
Chromatin associated proteins
8) pRB is a “master brake” in cell cycle regulation. pRb acts by masking key
transcription factors of the E2F family. What happens when pRB is
9) At the R (restriction) checkpoint in G1, what four considerations must be
addressed before the cell cycle can proceed?
10) There are also four factors that control entry into the M phase. List
these four factors.
11) Mutations of cyclins are often oncogenes and have a dominant phenotype
with respect to the formation of tumors. Conversely, mutations of CDK
inhibitors are often tumor supressor genes and have a recessive
phenotype. Explain the differences between these two types of cancer-