Recording-2025-02-22T16_48_45.263Z

What is the main task of cell division regarding genetic material?

Proper duplication and segregation of the genetic material.

What are the four phases of the cell cycle?

G1, S, G2, and M phase.

What is the role of molecular triggers in the cell cycle control system?

They drive the progression of the cell cycle and ensure events occur in a specific order.

What do checkpoint components do in the cell cycle?

They stop the cell cycle at specific points if certain criteria are not satisfied.

What signals do most cells require to enter the cell cycle?

Positive extracellular signals called mitogens.

How do mitogens affect the RB protein?

Mitogens activate receptors, leading to the phosphorylation and inactivation of the RB protein, thus releasing transcription regulators.

What is RB in the context of cell cycle control?

RB is an important tumor suppressor that inhibits transcription factors necessary for cell cycle progression.

What are cyclin-dependent kinases (CDKs)?

CDKs are kinases that require binding to cyclins for their activity and are essential for regulating the cell cycle.

How does S CDK influence DNA replication?

S CDK phosphorylates a repressor of DNA replication, allowing DNA replication to proceed.

What changes occur during prophase of mitosis?

DNA condenses into chromosomes; centrosomes duplicate and initiate the spindle assembly.

What happens during the prometaphase of mitosis?

The nuclear envelope breaks down, allowing microtubules to attach to chromosomes.

What are the main tasks of the spindle checkpoint?

To ensure all chromosomes are properly attached to the spindle microtubules before proceeding to anaphase.

What does the anaphase promoting complex (APC) do?

APC triggers the degradation of proteins, including cyclins, to allow progression past metaphase.

Describe the roles of dyneins and kinesins in anaphase.

Dyneins pull the centrosomes apart and kinesins push the mitotic spindle poles apart.

How is the contractile ring formed during cytokinesis?

The contractile ring is formed by actin and myosin filaments that interact with the plasma membrane.

What is p53's role in the cell cycle?

p53 activates checkpoint responses to DNA damage and regulates the cell cycle inhibitors.

How do CDKs achieve their ordered activity during the cell cycle?

Different CDKs are activated sequentially by prior CDKs, maintaining a fixed order of events.

What event marks the exit from M phase?

The degradation of M cyclin by the APC complex.

What is the significance of the S phase in the cell cycle?

S phase is the stage where DNA replication occurs.

What roles do the cohesin complex play during cell division?

Cohesin holds sister chromatids together until anaphase.

What happens to the nuclear envelope during mitosis?

It disassembles during prophase and reassembles during telophase.

What is the consequence of DNA damage during the cell cycle?

The cell cycle is halted to allow for repair before continuing division.

How is cyclin degradation timed with cell cycle progression?

Cyclins are degraded at specific points via ubiquitination triggered by CDK activity.

What are the three types of microtubules involved in anaphase?

Astral microtubules, kinetochore microtubules, and non-kinetochore microtubules.

What induces the assembly of the contractile ring at the site of cytokinesis?

The localization of the signaling protein RhoA helps direct contractile ring assembly.

What phase occurs between the S phase and M phase of the cell cycle?

G2 phase.

What is the function of the kinetochore during chromosome movement?

The kinetochore aids in the attachment of chromosomes to spindle microtubules.

What checkpoints exist in the cell cycle?

Checkpoints at G1, S, G2, and M phases check for DNA damage and proper chromosome alignment.

What event marks the transition from metaphase to anaphase?

Activation of the anaphase promoting complex (APC).

What does the term 'cytokinesis' refer to?

The division of the cytoplasm to form two daughter cells after mitosis.

How are the Golgi and endoplasmic reticulum affected during cell division?

The Golgi fragments, and the endoplasmic reticulum is divided during cytokinesis.

What regulates the activity of CDK during the cell cycle?

The association of CDK with its corresponding cyclin regulates its activity.

What does the term 'mitogen' refer to?

Extracellular signal molecules that stimulate cell division.

What mechanism allows the cell to respond to DNA damage during G1 and S phases?

Activation of p53 leads to the production of CdK inhibitors.

What role do motor proteins play in chromosome movement during anaphase?

They facilitate chromosome movement towards the spindle poles.

Why is precise timing important during cell division?

To ensure proper replication and segregation of genetic material.

What happens to sister chromatids during anaphase A?

They are separated and pulled towards opposite spindle poles.

What are common outcomes of unchecked cell cycle progression, such as in cancer?

Uncontrolled cell proliferation and accumulation of mutations.

What determines when a cell can enter mitosis?

The activation of M CDK ensures the cell is ready to enter mitosis.

How does the environment affect cell cycle progression?

External signals influence whether cells receive the go-ahead to divide.

How do CDKs contribute to the regulation of the cell cycle?

CDKs phosphorylate target proteins, driving the progress of the cycle.

What is a crucial function of the APC during anaphase?

To promote the separation of sister chromatids by degrading securin.

What is essential for the assembly of a contractile ring during cytokinesis?

Actin polymerization and myosin filament assembly initiated by RhoA.

What is the role of the S phase checkpoint?

To verify that DNA is fully replicated and undamaged prior to mitosis.

What happens to the chromatin at the end of mitosis during telophase?

The chromosomes decondense back into chromatin.

How do G1 cyclins assist in cell cycle control?

They activate G1 CDKs to prepare the cell for entry into S phase.

Why is periodic cyclin degradation important for the cell cycle?

It ensures that CDKs are only active at appropriate times.