Cell Cycle Regulation and Checkpoints

These flashcards cover key vocabulary and concepts related to the cell cycle and its regulation, including checkpoints, proteins involved, and genetic implications.

Cyclins

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

Cyclin-Dependent Kinases (CDKs)

Enzymes that, when activated by cyclins, phosphorylate target proteins to promote progression through the cell cycle.

Checkpoints

Control mechanisms in the cell cycle that ensure all conditions are favorable before progression to the next stage.

Mitogen

A molecule that stimulates cells to divide by promoting entry into the cell cycle from a quiescent state (G0).

Proto-Oncogene

A normal gene that can become an oncogene due to mutations, leading to cancer.

Oncogene

A mutated form of a proto-oncogene that promotes uncontrolled cell division.

Tumor Suppressor Gene

A gene that normally inhibits cell division; loss of function can result in cancer (e.g., p53).

p53

A tumor suppressor protein that activates DNA repair proteins and regulates the cell cycle.

Loss-of-Function Mutation

A mutation that results in reduced or no function of a gene or protein.

Gain-of-Function Mutation

A mutation that enhances the function of a gene or protein, often leading to uncontrolled cell growth.

Kinase Inhibitor

Proteins that inhibit the activity of kinases, such as CDKs, thereby regulating cell cycle progression.

Cohesin

A protein that holds sister chromatids together during cell division.

Separase

An enzyme that cleaves cohesin, allowing sister chromatids to separate.

Anaphase-Promoting Complex (APC)

A complex that triggers the transition from metaphase to anaphase by activating separase.

Mad/Bub Proteins

Proteins that serve as inhibitors to the activation of APC in the presence of unattached chromosomes.

Aneuploidy

An abnormal number of chromosomes in a cell, often resulting from errors in the metaphase checkpoint.

Mitotic Arrest

A cell cycle checkpoint where cells are halted in mitosis, often due to disruptions in chromosome alignment.

Apoptosis

Programmed cell death that can occur when cells fail to pass critical checkpoints.

Cell Cycle Phases

The stages of the cell cycle: G1, S, G2, and Mitosis.

G1 Checkpoint

A checkpoint that assesses DNA damage and environmental conditions before cell enters S phase.

G2 Checkpoint

A checkpoint that ensures DNA replication is complete and there is no DNA damage before entering mitosis.

Metaphase Checkpoint

A checkpoint that confirms all chromosomes are properly attached to the spindle fibers before proceeding to anaphase.

p21

A CDK inhibitor that is upregulated by p53, blocking CDK activity to prevent cell cycle progression.

Quiescent Cells (G0)

Cells that are in a dormant state and not actively dividing, can be stimulated to re-enter the cell cycle.

CDK:cyclin Complex

The active enzyme complex formed by the binding of a cyclin to a CDK, which drives the cell cycle forward.

Phosphorylation

The addition of a phosphate group to a molecule, often used to activate or deactivate proteins in signaling pathways.