Cell cycle in Eukaryotes Flashcards
1
Q
What is the cell cycle
A
- Repeated process by which the cell duplicates itself and divides into two daughter cells
- Continuous cell divisions since beginnings of life on earth
- The cell cycle is controlled
- embryos show co-ordinated waves of cell division
2
Q
What can the loss of cell cycle control result in
A
- Loss of cell cycle control is a key step in cancer formation
- Identifying regulators of the cell cycle is important:
- tumour suppressors or proto-oncogenes
- predict people at risk
- potential drug targets
3
Q
What are the basic events in the cell cycle
A
- Duplicate cytoplasmic components (cell growth)
- Chromosome duplication
- Chromosome segregation
- Cytoplasmic segregation
4
Q
What happens in Prophase
A
- The chromosomes begin to condense.
- The centrosomes begin to assemble at the poles of the cell.
- Nuclei starts to breakdown- no longer nuclear envelope
5
Q
What happens in Prometaphase
A
- Microtubules from centrosomes start to project and radiate out into cells
6
Q
What happens in Metaphase
A
- The chromosomes align along the plane that bisects the cell and become attached to the microtubule fibres of the mitotic spindle.
7
Q
What happens in Anaphase
A
- Segregation occurs; the sister chromatids are pulled apart by the mitotic spindle to the two opposite poles of the cell.
8
Q
What happens in telophase
A
- The chromatids de-condense and a new nuclear membrane forms around each new set of chromosomes.
9
Q
How is the cell cycle regulated
A
- Controlled by checkpoints
- If problem- there is a pause for it to be rectified or for cell to exit cell cycle and not divide
- Checkpoints there to detect problem in External and Internal environment
10
Q
What happens in the first checkpoint
A
- Check if favourable internal environment
- Right number of organelles
- Correct amount of duplication etc
11
Q
What is checked at the second checkpoint
A
- All DNA needs to have been duplicated
12
Q
What is checked at the third checkpoint
A
- Make sure anaphase is triggered at correct time
13
Q
What may happen without the first checkpoint
A
- Start checkpoint
- Inappropriate cell proliferation
- lack of nutrients
- → cell death
- → malformed tissues
- → cancer
14
Q
What may happen without the G2/M checkpoint
A
- Division without complete DNA duplication
- daughter cells lack full complement of chromosomes (aneuploidy)
- → cell death
- → cancer
15
Q
What may happen without the Metaphase/Anaphase transition checkpoint
A
- Division with incomplete chromosome attachment
- daughter cells with uneven amounts of DNA (aneuploidy)
- → cell death
- → cancer