Meiosis

Question 1

Define diploid (2n)

Answer 1

A cell with a nucleus containing two full sets of chromosome

Question 2

Define haploid (n)

Answer 2

A cell with a nucelus containing one complete set of chromosome

Question 3

Define Gonads

Answer 3

The sex organs in animal

Question 4

Define crossing over (recombination)

Answer 4

The process by which large multi-enzyme complexes cut and re-join parts of the maternal and paternal chromatids at the end of prophase 1, introducing genetic variation

Question 5

Define chiasmata

Answer 5

The point where chromatids break during recombination

Question 6

Define independent assortment (random assortment)

Answer 6

The process by which the chromosome derived from the male and female parent are distributed into the gametes at random occurs in metaphase 1

Question 7

Define bivalent

Answer 7

Pair of chromosome

Question 8

List what causes the Variation

Answer 8

Random fertilisation

Independant assortment

Crossing over

Mutation

Question 9

Process of crossing over

Answer 9

Non sister chromatids from a homologous paurs of chromosome (bivalent) twist arounf one another at points called chiasmata -puts tension on the chromatid causing pairs the chromatid to break

Broken parts of the chromatids recombine with the anothher chromatid x> equal section of DNA containg the same gene swap

-new combination off maternal and paternal allele form

—->Recombinant forms

Question 10

Process of independant assortment

Answer 10

-Maternal and paternal chromosome are distributed into the gamete complete tly at random

• honologous pairs of chromosome line up oppositie each other at the equator of the cell
• it is random whcih side of the equator the paternal and maternal chromosome from each homologous pair lie
• these pair are separated, so one for each homologous pair ends up in the daughter cell
• create a large number of possible combination of chromosome in the daughter cells produced

Question 11

Prophase 1

Answer 11

Chromosome condenses & become visible

-homologous chromosome link togther forming chiasmata
—> crossing over take place (exchanging alleles between the homologous chromosome)

• nuclear envelope breaks down
• centrioles move opposite poles and forms
• spindle forms

Question 12

Metaphase 1 (middle)

Answer 12

-pairs of homologous chromosome are align along the equator of the spindle apparatus

Question 13

Anaphase 1 (apart)

Answer 13

Spindle fibre shorten

Homologous chromosome moves towards opposite poles

• the chiasmata between homologous chromosome breaks

Question 14

Telophase 1

Answer 14

Chromosome reach the poles of the cell

Nuclear envelope reformed
Centrioles and spindle fibre breaks down
Chromosome uncoiled

Undergo cytokinesis dividing into two cells - no longer pairs of homologous chromosome
- no further replication of DNA

Question 15

Prophase 2

Answer 15

• chromosome condense & become visible again
• nuclear envelope breaks down
• spindle fibre develop

Question 16

Metaphase 2

Answer 16

Chromosome (made up of pairs of chromatids) align along the equatoe of the spindle apparatus

Question 17

Anaphrase 2

Answer 17

• centromere of each chromosome divdes
• chromatids move to the opposite ends of the cells

Spindle fibre shortens

Question 18

Telophase 2

Answer 18

Nuclear envelope reforms

Chromatids reached the poles of the cell & now called chromosome

Chromosome uncoil back to their interphase state (chromatin state)

Each cell undergoes cytokinesis to produce 4 daughter cells each with half the chromosome number of the original diploid cell

Question 19

What happens in meiosis 1

Answer 19

Homologous chromosomes are separated from each other

Question 20

What happens in meiosis 2

Answer 20

Sister chromatids are separated from each other