4 Genetics - Meiosis Flashcards
1
Q
How does meiosis begin?
A
With a diploid parent cell, containing 2n of resulting chromosomes. (e.g 4 = diploid, 2 = haploid)
2
Q
Stage 1 of meiosis
A
Interphase 1/ Prophase 1, this is where chromosomes replicate to form pairs of chromatids, joined at the centromere, becoming chromosomes.
3
Q
Stage 2 of meiosis
A
- metaphase 1/ anaphase 1, homologus chromosome pairs (bivalent) line up on equator of the cell
4
Q
Stage 3 of meiosis
A
- anaphase 1, the homologus chromosomes separate as they are pulled to opposite poles of the cell by spindle fibres.
5
Q
Stage 4 of Meiosis
A
- telophase 1, the parent cell divides, new nuclear membrane forms around nucleus of haploid cells
6
Q
Stage 5 of meiosis
A
- Prophase 2 and metaphase 2, the nuclear membrane of the 2 cells produced from telophase 1 breaks down and the chromosomes arrange themselves at the equator of the cell
7
Q
What happens in stage 6 of meiosis?
A
- anaphase 2, the chromosomes divide at the centromere after being pulled apart by the spindle fibres, the chromatids separate become individual chromosomes
8
Q
What happens in stage 7 of meiosis?
A
- telophase 2, 2 cells divide to produce 4 haploid cells - gametes, ready to be fertilised during reproduction, these will then fuse to contain the whole number of chromosomes per cell instead of half.
9
Q
What are bivalent chromosomes?
A
- chromosomes where sections of DNA (chaismata) - sections of identical legnths, are swapped over, this increases genetic diversity.
- occurs in prophase 1
10
Q
Where does meiosis occur?
A
- reproductive organs
- testes (male)
- ovaries (female)
11
Q
What are homologus chromosome pairs
A
x1 maternal chromatid
x 1 paternal chromatid
- these make up an entire chromosome
12
Q
overall process of meiosis?
A
PMAT 1
PMAT 2
13
Q
Whar are causes of genetic variation in meiosis?
A
- Random assortment
- Chaismata (crossing over)
14
Q
What is the product of meiosis?
A
4 daughter haploid cells
