cell cycle

Apoptosis

The process of programmed cell death where a cell undergoes an orderly breakdown of its components.

Cell Cycle Checkpoints

Regulatory mechanisms that monitor and control the progression of the cell cycle, ensuring errors are repaired before proceeding.

Cyclin Proteins

Regulatory proteins that control progression through the cell cycle by activating cyclin-dependent kinases (CDKs).

Cyclin-Dependent Kinases (CDKs)

Enzymes that require cyclins to be activated and are responsible for phosphorylating target proteins to drive the cell cycle.

Proteasome

A cellular structure that degrades and disposes of unneeded or damaged proteins.

Biochemical Errors

Failures in cellular processes, such as DNA damage or incomplete replication, that activate cell cycle checkpoints.

G1 Checkpoint

The checkpoint that assesses cell growth, DNA integrity, and resource availability before the cell moves into the S phase.

G2 Checkpoint

The checkpoint that verifies DNA replication and cellular conditions before the cell enters mitosis.

M Phase Checkpoint

The checkpoint that ensures chromosomes are properly aligned and attached to the spindle apparatus during metaphase.

Cancer Cells and Checkpoints

Certain cancer cells can ignore one or more checkpoints, leading to uncontrolled growth.

Control of Apoptosis in Cancer

Mutations in cancer cells can prevent the apoptosis mechanism, allowing damaged cells to survive.

Role of Ubiquitin in Cyclin Regulation

Ubiquitin marks cyclins for degradation by proteasomes after their task is complete, preventing accumulation.

Defective Cell Cycle Regulation Consequences

Can lead to abnormal growth, benign or malignant tumors, and immune dysfunction.