Meiosis

Question 1

What is the formula for possible chromosome combinations?

Answer 1

(2^n)^2
n = Number of homologous pairs

Question 2

What is the process for Meiosis

Answer 2

Dna replication to form chromosomes, chromatids held together by centromere
Crossing over and recombination of alleles can occur rarely
Homologous chromosomes line up in pairs randomly via independent segregation
Division 1 occurs, homologous chromosomes separate into daughter cells
Division 2 occurs, chromatids separate into daughter cells
4 daughter cells are produced - gametes or haploid

Question 3

What is an allele

Answer 3

Different form of the same gene

Question 4

What causes genetic variation in meiosis

Answer 4

Crossing over and recombination
Independent segregation

Question 5

Why do only few gametes have new allele combinations

Answer 5

Crossing over and recombination is a rare event

Question 6

Why is meiosis important

Answer 6

Maintains constant chromosome number
50/50 split in generic material in fertilisation
Allows 2 haploid numbers to combine to form a diploid number

Question 7

How does independent segregation occur

Answer 7

Each chromosome lines up next to homologous partner
Chromosomes randomly arrange in pairs
Different pairs will be present in each daughter cell
Combination of maternal and paternal origin will be due to chance

Question 8

What are homologous chromosones

Answer 8

A pair of chromosomes which contain genes which code for the same characteristics
Alleles can alter these characterstics

Question 9

Genetic recombination by crossing over

Answer 9

Chromatids of each pair become twisted
Tensions created and portions of chromatids break off
Broken portions may rejoin with chromatids of homologous partner
Usually equivalent portions exchanged
New paternal and maternal alleles produced

Question 10

What is non disjunction

Answer 10

the failure of the chromosomes to separate, which produces daughter cells with abnormal numbers of chromosomes