meiosis

Question 1

what is the product of mitosis?

Answer 1

4 haploid daughter cells that are genetically different. they are GAMETES

Question 2

what is crossing over?

Answer 2

the process where a chromatid breaks during meiosis and parts the chromatids (lengths of DNA) are exchanged between the homologous pairs. The chromosomes cross over at points called chiasma and at each chiasma the chromosomes break and re-join, swapping some of their genes

Question 3

what is the result of crossing over?

Answer 3

the chromatids have the same genes but have different alleles which increases genetic diversity

Question 4

what is independent segregation?

Answer 4

during meiosis 1, the maternal and paternal chromosomes separate and can move to the ends of each daughter cell randomly. This is independent of other chromosomes. It is random each time which side of the equator the paternal and maternal chromosome of each homologous pair align, and as a result, each gamete receives different combinations of the maternal and paternal chromosomes

Question 5

how many combinations of chromosomes can their be and why?

Answer 5

2^23 as there is 23 pairs of chromosomes

Question 6

explain the stages of meiosis

Answer 6

-DNA replicates and condenses to form chromosomes, each made up of 2 chromatids joined at the centre by a centromere
-Chromosomes are arranged in homologous pairs at the centre of the cell
-then they are moved apart by spindle fibres and this separation is random.
-MEIOSIS 1, the cell divides into 2 cells which produces 2 genetically different cells
-sister chromatids are separated by spindle fibres and pulled to opposite ends
-MEIOSIS 2, the cell divides into 2 and 1 chromatid from chromosomes is separated into each cell and so 4 genetically different haploid cells are produced.

Question 7

what are the 2 main stages of meiosis?

Answer 7

meiosis I and meiosis II

Question 8

what stages are within each division of meiosis?

Answer 8

prophase, metaphase, anaphase, telophase

Question 9

explain how the chromosome number is halved during meiosis

Answer 9

homologous chromosomes are pulled apart by spindle fibres during anaphase to opposite poles of the cell. This means that each daughter cell receives 1 chromatid instead of 2