Cytokinesis, Cell Cycle Control, Mitosis

What structure forms during animal cytokinesis?

A cleavage furrow formed by contracting microtubules.

What do plant cells need to form during cytokinesis?

A new cell wall, created by vesicles that form the cell plate.

What is the average duration of the cell cycle in human cells?

Approximately 24 hours.

How long can the cell cycle take in budding yeast under optimal conditions?

About 90 minutes.

What is the G1 stage of interphase?

The gap phase where ribosomes and some organelles begin to duplicate.

What is the G2 stage of interphase?

The phase where microtubules begin to form in preparation for mitosis.

What is the role of S-cyclin?

To stimulate DNA replication during the S phase.

What is phosphorylation?

The addition of a phosphate group (PO4) to an organic molecule.

What happens when CDKs are activated?

They begin phosphorylating messenger compounds to trigger cell cycle progression.

What is the G0 phase?

A phase where cells are terminally differentiated and do not divide.

What is the role of SRC protein kinase?

To pass information from outside to inside the cell.

What initiates the enzymatic activity of the receptor proteins?

The binding of growth factors.

What happens to RAS when GDP is bound?

It becomes inactive.

What is the function of RAF kinase?

To become activated by RAS and propagate the signaling cascade.

What is the significance of the cell cycle checkpoints?

They control the progression through the cell cycle stages.

What is the typical cell cycle duration for human intestinal lining cells?

About 9-10 hours.

What characterizes human nerve cells in terms of cell division?

They are in the G0 phase and do not divide in adults.

What occurs when a threshold is reached in CDK activation?

It triggers the replication of DNA and other cell cycle processes.

Why do cells need to reproduce?

Cells reproduce to replace old or damaged cells and to allow organisms to grow.

What is the consequence of growing a cell too large?

A cell can burst due to limitations in surface area and volume ratios.

What are the two main processes of cell reproduction in eukaryotes?

Nuclear division (mitosis) followed by cytoplasmic division (cytokinesis).

What are the two main phases of the cell cycle?

Interphase and Mitosis.

What is the outcome of mitosis?

Mitosis yields genetically identical daughter cells.

How many daughter cells are produced from one nuclear division?

Two daughter cells.

What happens during cytokinesis?

Cytokinesis is the division of the cytoplasm following mitosis.

What is the role of cyclins and kinases in the cell cycle?

Cyclins and kinases regulate the progression of the cell cycle.

What is positive regulation in the context of the cell cycle?

Positive regulation refers to mechanisms that promote cell cycle progression.

What is a centromere?

A centromere is the constricted region of a replicated chromosome.

What are kinetochores?

Kinetochores are proteins on the sides of chromosomes that attach to spindle fibers.

What are microtubules' role in mitosis?

Microtubules assemble to form the spindle fibers that help separate chromosomes.

What is the significance of DNA replication being semi-conservative?

It means that each new DNA molecule consists of one original strand and one new strand.

What is prophase?

Prophase is the preparing stage of mitosis where DNA condenses into chromosomes and the nuclear membrane begins to break down.

What occurs during metaphase?

Chromosomes line up in the middle of the cell on the metaphase plate.

What happens during anaphase?

Replicated chromosomes separate and move to opposite ends of the cell.

What is telophase?

Telophase is the stage where the nuclear membrane reforms and chromosomes unwind back to chromatin.

What often begins during telophase?

Cytokinesis often begins during telophase.

What is the role of helicase during DNA replication?

Helicase unwinds the DNA double helix.

What is the function of DNA polymerase?

DNA polymerase synthesizes new DNA strands by adding nucleotides.

What is the role of primase in DNA replication?

Primase synthesizes a short RNA primer to initiate DNA synthesis.

What does ligase do in DNA replication?

Ligase joins Okazaki fragments on the lagging strand during DNA replication.