29 Questions
What is the primary role of the cohesin proteins in eukaryotic cells?
To link together sister chromatids after replication and keep them together during chromosome condensation
How do the condensin proteins affect the structure of DNA when they bind to it?
They create positive supercoils in the DNA, causing it to become overwound
Which of the following is NOT a key transition point in the eukaryotic cell cycle?
The point where chromosomes condense as cells enter mitosis
Which of the following statements about SMC proteins is true?
SMC proteins are a class of chromatin proteins, in addition to histones and topoisomerases
What is the main function of the condensin proteins in eukaryotic cells?
To maintain the condensed structure of chromosomes during mitosis
Which of the following cell types are most likely to rarely or never divide?
Nervous and heart cells
What are the red bars indicating in the eukaryotic cell cycle?
Points where the cell can exit and enter a nondividing state
What are cyclins in relation to the cell cycle regulation?
Proteins regulating the timing of the cell cycle
What are internal regulators in the cell cycle control process?
Respond to events inside the cell
What is the consequence of uncontrolled cell growth as mentioned in the text?
Cells invade other normal cells' space
What is a characteristic of a benign tumor mentioned in the text?
Responds to 'stop' signals
How does apoptosis relate to uncontrolled cell growth?
Results in programmed cell death
What triggers the activation of the gene coding for the p21 protein?
Phosphorylated p53 protein accumulation
Which protein promotes apoptosis by binding to and blocking the action of the apoptosis inhibitor Bcl-2?
Puma
What is the main protein destruction machine in a cell?
Proteasome
What happens when the DNA damage cannot be repaired and p53 is activated?
Genes encoding proteins that trigger cell death by apoptosis are activated
Which event leads to cell cycle arrest at the restriction point?
Inhibition of Cdk-cyclin by p21 protein
What role does the Rb protein play in cell cycle control?
It binds to E2F and prevents it from activating transcription of genes required for DNA replication
What event triggers the onset of S phase in cells stimulated by growth factors?
Activation of the Ras pathway and subsequent phosphorylation of the Rb protein
What happens to the Rb protein during M phase?
It is dephosphorylated so that it can once again inhibit E2F
What event leads to the activation of checkpoint kinases and subsequent phosphorylation of the p53 protein?
Damaged DNA
What is the role of the E2F transcription factor in cell cycle control?
It activates the transcription of genes coding for proteins required for DNA replication when not bound to the Rb protein
What is the role of the G1 Cdk-cyclin complex in cell cycle control?
It phosphorylates the Rb protein, causing it to dissociate from E2F and allow gene transcription
What is the primary role of the Mdm2 protein in relation to p53?
It marks p53 for degradation
How does the accumulation of phosphorylated p53 lead to cell cycle arrest?
It activates the transcription of the p21 gene, which inhibits Cdk-cyclin complexes
What is the role of the Puma protein in the p53 pathway?
It promotes apoptosis by binding to and blocking the action of Bcl-2
Which of the following protein kinases is responsible for initiating the p53 response to DNA damage?
ATM or ATR
What is the consequence of the inhibition of Cdk-cyclin complexes by p21?
It prevents the phosphorylation of the Rb protein, leading to cell cycle arrest
What is the primary function of the Bcl-2 protein in the p53 pathway?
It inhibits apoptosis by blocking the action of Puma
Test your knowledge about SMC proteins, a class of chromatin proteins that help maintain condensed chromosome structures. Learn about the role of cohesins and condensins in eukaryotes as well as their importance in various organisms.
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