2.6 Meiosis

Question 1

What sort of division does meiosis involve?

Answer 1

A reduction division

Question 2

What is a reduction division?

Answer 2

Cells have full number of chromosomes to start but the cells formed have half the number

Question 3

What is the name for a cell with half the number of chromosomes?

Answer 3

Haploid cell

Question 4

Why are the cells made genetically different?

Answer 4

Because each ends up with a different arrangement of chromosomes

Question 5

How many divisions occur in meiosis?

Answer 5

2

Question 6

What are the stages of the first mitotic division?

Answer 6

Interphase 1
Prophase 1
Metaphase 1 
Anaphase 1
Telophase 1 
Cytokinesis

Question 7

What occurs in inter phase 1?

Answer 7

Chromatin is not visible

DNA and proteins are replicated

Question 8

What occurs in prophase 1?

Answer 8

• Chromosomes condense (get shorter and fatter)
• Chromosomes arrange into homologous pairs
• crossing over occurs
• centrioles move to opposite poles

Question 9

What occurs in metaphase 1?

Answer 9

• Homologous pairs (bivalent) align on equator
• independent assortment occurs resulting in genetic variation
• pairs attachment to spindle fibres

Question 10

What occurs in anaphase 1?

Answer 10

• spindles contract
• homologous pairs separate
• one chromosome from each pair moves to each side of cell

Question 11

What occurs in telophase 1?

Answer 11

• Nuclear envelope forms

* cells formed have 2 chromosomes

Question 12

What occurs in cytokinesis?

Answer 12

Cytoplasm divides

2 haploid daughter cells produced

Question 13

What are the phases of the second mitotic division?

Answer 13

Interphase 2
Prophase 2
Metaphase 2
Anaphase 2
Telophase 2

Question 14

What occurs in interphase 2?

Answer 14

Shorter
No DNA replication
Chromosomes remain visible

Question 15

What occurs in prophase 2?

Answer 15

Centrioles replicate and move to new poles
Chromosomes condense
Nuclear envelope breaks down
Spindle forms

Question 16

What occurs in metaphase 2?

Answer 16

Chromosomes align on equator
Independent assortment
Crossing over

Question 17

What occurs in anaphase 2?

Answer 17

Centromeres split

Chromatids separate

Question 18

What occurs in telophase 2?

Answer 18

4 haploid cells each with 2 chromatids produced (1 from each parent)

Question 19

What is crossing over?

Answer 19

Homologous pairs of chromosomes come together. Chromatids twist around each other and bits of chromatids swap. Resulting in different combinations of alleles

Question 20

What are the 2 processes resulting in genetic variation in meiosis?

Answer 20

Crossing over

Independent assortment

Question 21

What happens in independent assortment?

Answer 21

Homologous chromosomes contain one from the father and one from the mother
When they align (m1) and separate (a1) it is completely random which chromosome ends up in each daughter cell

Question 22

What does independent assortment lead to?

Answer 22

4 daughter dells having completely different combinations of maternal and paternal chromosomes

Question 23

What does meiosis do?

Answer 23

Produces gametes for sexual reproduction