Name 3 different asexual reproduction methods in which cell division is involved.
- Binary Fission
- Budding
- Parthenogenesis
Name all phases of the cell cycle
G1 phase- Cells double in size
S phase- DNA replication occurs
G2 phase- Organelles are duplicated and cell prepares for mitosis
Prophase- Chromatin condense and become visible. Nuclear envelope breaks down.
Metaphase- Chromosomes visible and arrange at central plane of cell (metaphase plate)
Anaphase- Sister chromatids are pulled to opposite poles of cell. Now two single chromatid chromosomes
Telophase- new nuclei reform, chromatin decondenses and the interphase cytoskeleton is established
What happens during cytokinesis?
A cleavage furrow forms between the two nuclei on the original plane of the metaphase plate. Pinching off to form two separate cells.
How is the cell cycle controlled?
- Checkpoints through the cell cycle.
- Only very few cells retain the ability to divide
What would happen if DNA was damaged during the G1 stage?
- This would activate the G1/S-phase checkpoint, arresting the cell cycle.
- Time is allowed for repairs to DNA before replication
- If repair is not possible then the cell will initiate apoptosis
How is the G1 checkpoint controlled?
A retinoblastoma protein actively blocks the cell cycle. This is inactivated by a CDK (cyclin dependant kinase) the CDK can only inactivate it if it forms a complex with cyclin. This will only be produced if DNA replication occurs with no errors.
