Revised Answers Graded A+
10.1Q1 Describe the steps of M-CDKs activation. - Answer-Cyclin dependent kinases
have to associate with a cyclin to activate; M-cyclins associate with the kinase; more
steps with an activating kinase, inhibiting kinase, and a phosphatase that all receive
input signals to control when M-CDKs are active
10.2Q1 Why are M-Cdk and S-Cdk regulated by sequential cyclin activation in addition
to multiple phosphorylation and dephosphorylating steps? - Answer-The rise of cyclin
levels in the cell is what triggers different steps in the cell cycle and the phosphorylation
and dephosphorylation is what activates the Cdks.
10.3Q1 Describe how S-CDK controls initiation of DNA replication. - Answer-The S-
Cdk2-E complex associates with ORCs recruit's DNA polymerase and fires the
replication process.
10.4Q1 How does a centrosome emerge in the cell? - Answer-Centrosomes exist in
interphase as a single unit and they are copied only once per cell cycle and transferred
to offspring
10.5Q1 Define three stages of the cell cycle? - Answer-Interphase
G0: where cells rest
G1: where cells grow and expand
S: where DNA is replicated
G2: where cells repair damaged DNA and duplicate centrosomes
Cell division (M) phase
Where cells undergo nuclear and cytoplasmic division
10.6Q1 What are cyclin-dependent kinases (Cdks)? - Answer-A small family of protein
kinases that regulate the transition of various phases in the cell cycle. CDKs are small
proteins that mainly carry a kinase domain which phosphorylates target proteins.
10.7Q1 What are cell cycle checkpoints? - Answer-G1/S checkpoint: triggers DNA
replication
G2/M checkpoint: checks for complete and accurate DNA replication, size, and
availability of chemical resources needed for cell division
M checkpoint: assures chromosome segregation and spindle assembly
10.8Q2 How do cohesins and codensins work? - Answer-Cohesins are sister
chromatids bundled together with specialized protein complexes