2.6 Meiosis Flashcards Preview

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Flashcards in 2.6 Meiosis Deck (23):
1

What sort of division does meiosis involve?

A reduction division

2

What is a reduction division?

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

3

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

Haploid cell

4

Why are the cells made genetically different?

Because each ends up with a different arrangement of chromosomes

5

How many divisions occur in meiosis?

2

6

What are the stages of the first mitotic division?

Interphase 1
Prophase 1
Metaphase 1
Anaphase 1
Telophase 1
Cytokinesis

7

What occurs in inter phase 1?

Chromatin is not visible
DNA and proteins are replicated

8

What occurs in prophase 1?

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

9

What occurs in metaphase 1?

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

10

What occurs in anaphase 1?

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

11

What occurs in telophase 1?

•Nuclear envelope forms
•cells formed have 2 chromosomes

12

What occurs in cytokinesis?

Cytoplasm divides
2 haploid daughter cells produced

13

What are the phases of the second mitotic division?

Interphase 2
Prophase 2
Metaphase 2
Anaphase 2
Telophase 2

14

What occurs in interphase 2?

Shorter
No DNA replication
Chromosomes remain visible

15

What occurs in prophase 2?

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

16

What occurs in metaphase 2?

Chromosomes align on equator
Independent assortment
Crossing over

17

What occurs in anaphase 2?

Centromeres split
Chromatids separate

18

What occurs in telophase 2?

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

19

What is crossing over?

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

20

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

Crossing over
Independent assortment

21

What happens in independent assortment?

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

22

What does independent assortment lead to?

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

23

What does meiosis do?

Produces gametes for sexual reproduction

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