Podcast
Questions and Answers
What is the role of the kinase Wee1?
What is the role of the kinase Wee1?
- it phosphorylates Cdc26
- it phosphorylates M-Cdk to inactivate it (correct)
- it dephosporylates M-Cdk to activate it
- it ubiquitinates p53 it phosphorylates cyclins
The anaphase-promoting complex (APC) triggers the onset of anaphase by:
The anaphase-promoting complex (APC) triggers the onset of anaphase by:
- cleaving spindle microtubules.
- phosphorylating the motor proteins that pull the spindle poles apart.
- triggering the destruction of Cohesins that hold the sister chromatids together. (correct)
- triggering the destruction of the condensins that hold the duplicated chromosomes in a condensed state. All of the above
The activation of M-Cdk begins abruptly, mainly because:
The activation of M-Cdk begins abruptly, mainly because:
- M-cyclin is bound to M-Cdk and the complex dephosphorylated by Cdc25 (correct)
- M cyclin decreases abruptly
- M cyclin gene transcription is rapidly activated
- M-Cdk gene transcription is rapidly increased All of the above
What process is necessary in llate G1 phase to transition to S phase?
What process is necessary in llate G1 phase to transition to S phase?
Place the cell cycle in the correct order.
Place the cell cycle in the correct order.
What would be the consequence of a Wee1 gene mutation that prevents the protein from being translated?
What would be the consequence of a Wee1 gene mutation that prevents the protein from being translated?
Which cell cycle phase is the shortest?
Which cell cycle phase is the shortest?
Meiosis I has which feature?
Meiosis I has which feature?
The nuclear envelope breaks down at the start of prometaphase because:
The nuclear envelope breaks down at the start of prometaphase because:
Which event triggers a pause in G1 phase?
Which event triggers a pause in G1 phase?
Study Notes
Cell Cycle Regulation
- Wee1 kinase inhibits M-Cdk activation, ensuring that mitosis is delayed until the DNA is fully replicated and checked for errors.
Anaphase Onset
- The anaphase-promoting complex (APC) triggers the onset of anaphase by ubiquitinating and degrading securin, which releases separase to cleave cohesion, allowing sister chromatids to separate.
M-Cdk Activation
- M-Cdk activation begins abruptly because Wee1 kinase, which inhibits M-Cdk, is inactivated, and Cdc25, which activates M-Cdk, is activated.
G1 Phase Transition
- The transition from G1 to S phase requires the activation of S-Cdk, which phosphorylates and inhibits Rb, allowing E2F to activate transcription of genes necessary for DNA replication.
Cell Cycle Order
- The correct order of the cell cycle is: G1 → S → G2 → M.
Wee1 Gene Mutation
- A Wee1 gene mutation that prevents the protein from being translated would lead to uncontrolled M-Cdk activation, causing premature entry into mitosis, which can result in chromosomal instability and cancer.
Cell Cycle Phases
- The shortest phase of the cell cycle is mitosis (M phase).
Meiosis I Feature
- Meiosis I is characterized by the reductional division, where the number of chromosomes is halved.
Nuclear Envelope Breakdown
- The nuclear envelope breaks down at the start of prometaphase because of phosphorylation of lamin by M-Cdk, allowing chromatin to condense and interact with the mitotic spindle.
G1 Phase Pause
- A pause in G1 phase can be triggered by the presence of DNA damage or other cellular stresses, which activate the p53 tumor suppressor protein to induce cell cycle arrest.
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Description
This quiz covers the regulation of the cell cycle, including the role of Wee1 kinase, M-Cdk activation, and the anaphase-promoting complex (APC) in delaying mitosis until DNA replication and error checking are complete.
