SMC Proteins and Chromosome Structures Quiz

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What is the primary role of the cohesin proteins in eukaryotic cells?

To regulate the ON and STOP switches for cell division

To link together sister chromatids after replication and keep them together during chromosome condensation (correct)

To maintain the condensed structure of chromosomes during mitosis

To induce positive supercoiling in DNA during chromosome condensation

How do the condensin proteins affect the structure of DNA when they bind to it?

They cause the DNA to become underwound

They have no effect on the DNA's supercoiling

They create positive supercoils in the DNA, causing it to become overwound (correct)

They induce negative supercoiling in the DNA

Which of the following is NOT a key transition point in the eukaryotic cell cycle?

The point where sister chromatids are segregated during cell division

The point where chromosomes condense as cells enter mitosis (correct)

The ON switch, where a cut or break in tissue causes cells to grow rapidly

The STOP switch, where cells stop growing when they bump into each other

Which of the following statements about SMC proteins is true?

SMC proteins are a class of chromatin proteins, in addition to histones and topoisomerases (D) Signup and view all the answers

What is the main function of the condensin proteins in eukaryotic cells?

To maintain the condensed structure of chromosomes during mitosis (C) Signup and view all the answers

Which of the following cell types are most likely to rarely or never divide?

Nervous and heart cells (B) Signup and view all the answers

What are the red bars indicating in the eukaryotic cell cycle?

Points where the cell can exit and enter a nondividing state (C) Signup and view all the answers

What are cyclins in relation to the cell cycle regulation?

Proteins regulating the timing of the cell cycle (B) Signup and view all the answers

What are internal regulators in the cell cycle control process?

Respond to events inside the cell (D) Signup and view all the answers

What is the consequence of uncontrolled cell growth as mentioned in the text?

Cells invade other normal cells' space (D) Signup and view all the answers

What is a characteristic of a benign tumor mentioned in the text?

Responds to 'stop' signals (C) Signup and view all the answers

How does apoptosis relate to uncontrolled cell growth?

Results in programmed cell death (D) Signup and view all the answers

What triggers the activation of the gene coding for the p21 protein?

Phosphorylated p53 protein accumulation (D) Signup and view all the answers

Which protein promotes apoptosis by binding to and blocking the action of the apoptosis inhibitor Bcl-2?

Puma (D) Signup and view all the answers

What is the main protein destruction machine in a cell?

Proteasome (C) Signup and view all the answers

What happens when the DNA damage cannot be repaired and p53 is activated?

Genes encoding proteins that trigger cell death by apoptosis are activated (B) Signup and view all the answers

Which event leads to cell cycle arrest at the restriction point?

Inhibition of Cdk-cyclin by p21 protein (A) Signup and view all the answers

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 (C) Signup and view all the answers

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 (C) Signup and view all the answers

What happens to the Rb protein during M phase?

It is dephosphorylated so that it can once again inhibit E2F (D) Signup and view all the answers

What event leads to the activation of checkpoint kinases and subsequent phosphorylation of the p53 protein?

Damaged DNA (A) Signup and view all the answers

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 (B) Signup and view all the answers

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 (A) Signup and view all the answers

What is the primary role of the Mdm2 protein in relation to p53?

It marks p53 for degradation (B) Signup and view all the answers

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 (C) Signup and view all the answers

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 (D) Signup and view all the answers

Which of the following protein kinases is responsible for initiating the p53 response to DNA damage?

ATM or ATR (B) Signup and view all the answers

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 (B) Signup and view all the answers

What is the primary function of the Bcl-2 protein in the p53 pathway?

It inhibits apoptosis by blocking the action of Puma (C) Signup and view all the answers