T5 module 2: Meiosis

Question 1

number of gametes created in male and females

Answer 1

male: 4 haploid gametes
female: 1 haploid gamete + 3 polar bodies

Question 2

key functions of meiosis

Answer 2

• reduces chromosomes # in gametes
• allows for genetic recombination

Question 3

meiosis process

Answer 3

INTERPHASE

MEIOSIS I

Prophase I
- condensation + synapsis (pairing of homologous chromosomes)
- crossing over (chiasma/chiasmata is where they cross)
- all other prophase processes
Metaphase I
- homologous pairs line up in middle of cell
- bivalents (crossed chromosomes) oriented randomly)
Anaphase I
- chromosomes separate, sister chromatids do not
Telophase I + cytokinesis
- daughter cells ready for prophase II
- now have 2 haploid cells (23 chromosomes each)

MEIOSIS II (same as mitosis)

Prophase II
Metaphase II
Anaphase II
Telophase II + cytokinesis
- left with 4 haploid cells

Question 4

errors in meiosis

Answer 4

NONDISJUNCTIONS

1st division NDJ
- homologous chromosomes don’t split
- 2 games with extra chromosome and 2 gametes missing a chromosome

2nd division NDJ
- sister chromatids don’t split
- 1 gamete extra chromosome, 1 without

Question 5

mendel’s laws of inheritance

Answer 5

1: LAW OF SEGREGATION
- offspring inherit 2 copies of a gene (different alleles)
- dominant will show

2: LAW OF INDEPENDENT ASSORTMENT
- only applies to genes on different chromosomes
- they will sort independantly of one another
- ratio = 9:3:3:1

Question 6

define monohybrids

Answer 6

offspring heterozygous for first trait followed in cross