9.2 Meiosis and genetic variation

Question 1

what is meiosis?

Answer 1

type of cell division that produces daughter cells that are genetically different

Question 2

why is meiosis important?

Answer 2

produces genetically different cells
- gametes
-allows the gametes to fuse for offspring

Question 3

what are gametes?

Answer 3

reproductive cells that fuse with another during fertilisation

Question 4

how many nuclear divisions does meiosis have?

Answer 4

2

Question 5

what are the products of meiosis?

Answer 5

4 haploid cells from one diploid (genetically different)

Question 6

what ways does meiosis bring about genetic variation?

Answer 6

independent segregation of homologous chromosomes

crossing over between homologous chromosomes

Question 7

what happens during independent segregation of homologous pairs?

Answer 7

maternal and paternal chromosomes are reshuffled in any combination

Question 8

how does the crossing over of chromosomes occur?

Answer 8

• the chromatids become twisted around one another
• the tension causes the chromatids to break off
• equivalent portions are exchanged
• new combinations of maternal and paternal

Question 9

What forms when 2 homologous pairs of chromosomes associate?

Answer 9

Bivalent
Chiasma

Question 10

What’s a bivalent?

Answer 10

2 chromosomes coming together

Question 11

What’s a chiasma?

Answer 11

The cross over point of two chromosomes

Question 12

How are new combinations of alleles made during cross over?

Answer 12

Equal lengths of non-sister chromatid are exchanged

Question 13

How does crossing over of chromatids affect genetic variation?

Answer 13

It increases generic variation by producing new combinations of alleles