AP Bio Insta-Review Topic 4.7*: Regulation of Cell Cycle

Front

What is the M checkpoint in the cell cycle?

Back

The M checkpoint, also known as the spindle checkpoint, is a regulatory point during the metaphase of mitosis that ensures all chromosomes are properly attached to the spindle apparatus before proceeding to anaphase.

Front

What is the purpose of the G1 checkpoint?

Back

The G1 checkpoint assesses the cell's size, nutrients, and DNA integrity before the cell enters the S phase, ensuring that conditions are favorable for DNA replication.

Front

What occurs during the S phase of the cell cycle?

Back

During the S phase, DNA replication occurs, resulting in the duplication of chromosomes, preparing the cell for mitosis.

Front

What is the role of cyclins in the cell cycle?

Back

Cyclins are proteins that regulate the cell cycle by activating cyclin-dependent kinases (CdKs), which drive the cell through different phases of the cycle.

Front

What is the G2 checkpoint responsible for?

Back

The G2 checkpoint verifies that DNA has been completely and accurately replicated and checks for DNA damage before the cell enters mitosis.

Front

How does the level of cyclin change during the cell cycle?

Back

Cyclin levels fluctuate throughout the cell cycle, increasing during specific phases to activate CdKs and then decreasing as the cycle progresses.

Front

What is the function of CdKs in the cell cycle?

Back

Cyclin-dependent kinases (CdKs) are enzymes that, when activated by binding to cyclins, phosphorylate target proteins to regulate the progression of the cell cycle.

Front

What is nondisjunction and which checkpoint prevents it?

Back

Nondisjunction is the failure of homologous chromosomes or sister chromatids to separate properly during cell division. The M checkpoint inhibits nondisjunction by ensuring proper spindle attachment.

Front

What triggers the transition from G2 to mitosis?

Back

The transition from G2 to mitosis is triggered by the accumulation of cyclins that bind to CdKs, leading to the activation of proteins necessary for mitosis.

Front

What is the significance of the metaphase checkpoint?

Back

The metaphase checkpoint ensures that all chromosomes are aligned correctly at the metaphase plate and attached to spindle fibers, preventing errors in chromosome segregation.