Cell cycle Flashcards
(23 cards)
What are the main phases of the cell cycle?
G1 (Gap 1), S (Synthesis), G2 (Gap 2), M (Mitosis), and G0 (Quiescent phase)
What happens during the G1 phase?
Cell grows, synthesises proteins, and prepares for DNA replication.
What happens during the S phase?
DNA replication occurs, resulting in duplicated chromosomes.
What happens during the G2 phase?
Cell continues to grow and checks for DNA replication errors.
What happens during the M phase?
The cell divides its chromosomes and cytoplasm to produce two identical daughter cells.
What is G0 phase in the cell cycle?
A resting state where the cell is metabolically active but not dividing.
What triggers a cell to enter the cell cycle from G0?
External signals like growth factors and mitogens.
What are cyclin-dependent kinases (CDKs)?
Enzymes that, when bound to cyclins, regulate progression through the cell cycle.
What is the function of CDK-cyclin complexes?
They drive transitions between cell cycle phases such as G1 to S and G2 to M.
What does p53 do in response to DNA damage?
Activates p21 to inhibit CDKs, halting the cell cycle to allow repair or trigger apoptosis.
What are the phases of mitosis?
Prophase, Prometaphase, Metaphase, Anaphase, Telophase, and Cytokinesis.
What happens in prophase?
Chromosomes condense and spindle fibres begin to form.
What happens in prometaphase?
Nuclear envelope breaks down and spindle fibres attach to chromosomes.
What happens in metaphase?
Chromosomes align along the cell equator.
What happens in anaphase?
Sister chromatids are pulled apart toward opposite poles.
What happens in telophase?
Nuclear membranes reform around the separated chromatids.
What is cytokinesis?
Division of the cytoplasm, completing cell division.
What are the main cell cycle checkpoints?
G1 checkpoint, G2 checkpoint, and M checkpoint.
What is the role of CDK inhibitors (CKIs)?
They block CDK activity to control progression through the cell cycle.
How does chemotherapy exploit the cell cycle?
By targeting rapidly dividing cells in S or M phase using drugs like methotrexate and paclitaxel.
What is apoptosis?
A form of programmed cell death that avoids inflammation.
What is necrosis?
Unregulated cell death causing swelling, rupture, and inflammation.
Name key proteins regulating apoptosis.
Bax and Fas (pro-apoptotic); Bcl-2 (anti-apoptotic).
