Cell Cycle Phases and Checkpoints

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Questions and Answers

During which phase of the cell cycle is DNA replication identified by labeling cells with radioactive thymidine?

  • G2
  • G1
  • S (correct)
  • M

What is the main function of the DNA damage checkpoint in late G2?

  • To ensure proper chromosome condensation
  • To promote spindle formation
  • To verify DNA replication and detect any damage (correct)
  • To regulate cyclin-dependent kinases

What is responsible for the ubiquitination of cyclins and structural proteins?

  • Cyclin-dependent kinases
  • Ubiquitin-dependent proteolysis
  • Mdm2
  • APC/C complex (correct)

Which of the following is a key biochemical principle of the cell cycle regulation?

<p>Ubiquitin-dependent proteolysis (B)</p> Signup and view all the answers

What is the role of the restriction point in the G1 phase?

<p>To look for growth signals (A)</p> Signup and view all the answers

What is the name of the complex responsible for the degradation of cyclins and structural proteins?

<p>APC/C complex (A)</p> Signup and view all the answers

What is the primary target of the APC/C complex during prometaphase?

<p>Cyclin A (B)</p> Signup and view all the answers

What is the primary event that occurs during the G1/S transition?

<p>D-type cyclins activate CDK4/6 (D)</p> Signup and view all the answers

What happens to chromosomes during early G1 phase?

<p>They decondense (B)</p> Signup and view all the answers

What is the function of the retinoblastoma protein (Rb) during the G1 phase?

<p>To block E2F transcriptional activity (B)</p> Signup and view all the answers

What is the outcome of a cell entering the G0 phase?

<p>The cell stops cycling but remains active (B)</p> Signup and view all the answers

What is the primary function of the APC/C complex during late mitosis?

<p>To target cyclin B for destruction (B)</p> Signup and view all the answers

What happens to p53 when it gets phosphorylated?

<p>Mdm2 can't bind to it (D)</p> Signup and view all the answers

What is the function of Cdk1 in the cell cycle?

<p>To phosphorylate lamins and break down the nuclear envelope (A)</p> Signup and view all the answers

What is the role of cyclin B in the cell cycle?

<p>To activate Cdk1 activity (D)</p> Signup and view all the answers

What happens to Cdk1 activity during late G2 phase?

<p>It becomes fully active after dephosphorylation by Cdc25 (C)</p> Signup and view all the answers

What is the effect of Wee1 on Cdk1 activity?

<p>It inhibits Cdk1 by phosphorylating T-14 and Y-15 (A)</p> Signup and view all the answers

What is the outcome of Cdk1/cyclin B kinase activity in the nucleus?

<p>Entry into mitosis (A)</p> Signup and view all the answers

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