6.1 - Cell Cycle Flashcards
What is the interphase?
Referred to as ‘growth period’
- 3 stages: G1, S, G2
- DNA replicated => checked for errors
- Protein synthesis in cytoplasm
- Mitochondria & chloroplast grow & divide
- Normal cell metabolism occurs
What process occurs throughout cell division?
Respiration
What occurs during G1?
1st growth phase
- Organelles are synthesised and produced => replicated
- Cell increases in size
CHROMOSOMES DO NOT REPLICATE IN G1
What occurs during the S phase?
S - synthesis
- DNA replication occurs
What occurs during G2?
2nd growth phase
- Cell continues to increase in size
- Energy stores increase
- Cell checks duplicated chromosomes and repairs error
What occurs during the mitotic phase?
Mitosis - nuclear division
Cytokinesis - cytoplasm divides producing 2 new identical daughter cells
What occurs during G0 and what are reasons for it?
Cells leaves cell - may be temporary or permanent
DNA ageing - cells becomes senescnet (gradual deterioration of functional characteristics
- DNA damaged, cell not viable and cannot divide
- Permanent cell arrest
- Most cells only divide for limited time > become secescent
- Cells specialise and can no longer divide - leaves to perform function and does not re-enter the cell cycle
What is the purpose of the cell cycle check points?
- DNA that is replicated must be checked for errors to ensure fidelity of daughter cells.
When is the G1 checkpoint and what does it check for?
- End of G1, before S phase
Checks for:
- Cell size
- Nutrients
- Growth factors
- DNA damage
If cell passes it goes to S phase, if not it goes to G0 (resting state)
When is the G2 checkpoint and what does it check for?
- End of G2, before mitotic phase
Checks for:
- Cell size
- DNA replication
- DNA damage
If cell passes it initiates the molecular processes that signal mitosis
What happens during the metaphase checkpoint of mitosis?
- Mitosis will not continue until all chromosomes are attached to spindle fibres and aligned.
