4.3 Meiosis

Question 1

Diploid cell definition

Answer 1

Have two sets of every chromosome

Question 2

Haploid cell definition

Answer 2

Have half the number if chromosomes - only 1 copy

Question 3

What are mutagenic agents?

Answer 3

Factors which increase the rate of gene mutation

Question 4

What is non-disjunction?

Answer 4

Failure of chromosomes to separate properly when producing daughter cells

Question 5

What does meiosis produce?

Answer 5

4 genetically dissimilar haploid cells

Question 6

What must occur before meiosis and why?

Answer 6

DNA replicates so there is two copies of every chromosome

- Zygotes would have double the number of chromosomes

Question 7

Meiosis I

Answer 7

• DNA condenses and forms double armed chromosomes with two sister chromatids joined at the centromere
• Chromosomes arrange in homologous pairs
• Homologous pairs separated

Question 8

Meiosis II

Answer 8

• Sister chromatids separate

- 4 haploid cells formed

Question 9

What is independent segregation?

Answer 9

In meiosis I when homologous pairs of chromosomes line up to be separated, it is random which chromosome ends up in the cell
- Daughter cells have completely different combinations of maternal and paternal chromosomes

Question 10

What is crossing over?

Answer 10

The exchange of sections of DNA between homologous chromosomes