Introduction to Mitosis Flashcards
what are the different stages of cell cycle?
- S phase: DNA duplication. 10-12 hours (1/2 cell cycle)
- M phase: chromosome segregation and cell divison (M for mitosis) (much less time)
- G1: Growth
G2 - Growth and prep for mitosis
order of cell cycle?
G1, S, G2, M
what is the interphase?
G1, S, G2 together
what is G0?
when do cells enter G0?
= specialised resting state in which the cells have left the cell cycle and are no longer dividing
cells enter G0 if:
-senescence (ageing)
- DNA damage
- Differentation (becomes specialised)
define mitosis
division of the nucleus of a eucaryotic cell, involving condensation of the DNA into visible chromosomes, and separation of the duplicated chromosomes to form two identical sets.
what are the four stages of mitosis (M phase)?
1. prophase:
2. metaphase
3. anaphase
4. telophase
what is the mitotic index?
how do you measure mitotic index?
The mitotic index is the ratio between the number of cells in mitosis (n) and the total number of cells (N). It is defined as the percentage of cells undergoing mitosis in a given population of cells.
Mitotic index = n/N × 100
A high proliferation rate (or a high mitotic index) could be a hallmark of what common condition?
cancer
The cell cycle is regulated. Why is this important?
To ensure that the chromosomes are in the correct position during mitosis.
To ensure that the cell has grown to the right size.
To ensure that the replicated DNA is error free (and has been repaired).
To ensure that nutrients and growth factors are available.
in cell cycle what helps to regulate agaisnt mistakes?
regulation at internal checkpoints: A checkpoint is one of several points in the eukaryotic cell cycle at which the progression of a cell to the next stage in the cycle can be halted until conditions are favorable
when do checkpoints occur?
hese checkpoints occur near the end of G1, at the G2/M transition, and during metaphase
