Meiosis

Question 1

How does meiosis differ from mitosis

Answer 1

Meiosis has
Genetic variation
Four daughter cells produced
Parent cells are diploids but daughter cells are haploids
Produces gametes

Question 2

Why do we need meiosis

Answer 2

Two gametes fuse om fertilisation to produce new offspring
New cells need 46 chromosomes
Chromosome number must be halved to maintain diploidy
Ensured by two meiotic divisions

Question 3

Sister chromatids

Answer 3

Identical arms on the same chromosome

Question 4

Meiosis process

Answer 4

1) DNA replicates in parent cell during interphase
2) Nuclear envelope and nucleolus break down
3) Maternal and paternal chromosomes pair up at the centre of the cell ( Different to mitosis)
5) Two meiotic divisions
4) Crossing over and separation of sister homologous chromosomes (I)
5) Seperation of sister chromatids (I)
6) Results in two genetically different gametes produced

Question 5

Two results of genetic variation

Answer 5

Crossing over and independent segregation

Question 6

Independent segregation

Answer 6

1) Homologous pairs line up -> one into each cell
2) Line arrangements are random
3)Independent segregation arises as combination of maternal and paternal chromosomes within daughter cell is random

Question 7

Crossing over

Answer 7

1) Homologous chromosomes line up
2) Non-sister chromatids overlap and entwine
3) Equivalent portions of chromatids exchanged and recombined
4) Recombinant chromatids are formed
5) New genetic combinations of maternal and paternal alleles are produced

Question 8

Chiasmata

Answer 8

Points of contact between homologous chromosomes during crossing over there are usually multiple