Genetic Diversity - Meiosis

Question 1

Meiosis

Answer 1

2 consecutive divisions of a diploid cell to produce 4 genetically unique haploid cells (gametes)

Question 1

can meiosis occur w/o cytokinesis?

Answer 1

yes

Question 2

why is meiosis called reduction division?

Answer 2

the number of chromosomes halves

Question 3

meiosis 1

Answer 3

separation of bivalents to produce 2 haploid daughter cells

Question 4

meiosis 2

Answer 4

separation of sister chromatids to produce 4 haploid daughter cells

Question 5

why are the daughter cells of meiosis 1 haploid?

Answer 5

the cells have half the number of chromosomes as the parent cell

Question 6

what do the haploid gametes contain?

Answer 6

1 chromatid of each chromosome

Question 7

how is prophase 1 different to mitosis and prophase 2?

Answer 7

chromosomes align as bivalents

Question 8

how is metaphase 1 different to mitosis and metaphase 2?

Answer 8

bivalents rather than chromosomes align at equator of spindle

Question 9

how is anaphase 1 different to mitosis and anaphase 2?

Answer 9

bivalents rather that sister chromatids are separated

Question 10

when does mitosis not produce diploid daughter cells?

Answer 10

when the parent cell is haploid

Question 11

purpose of mitosis

Answer 11

sexual reproduction

Question 12

2 functions of meiosis

Answer 12

1. produces haploid gametes so that at fertilisation, the diploid number can be restored
2. produces genetic variation (3 ways)

Question 12

how to distinguish meiosis 2 from meiosis 1?

Answer 12

spindle fibre forms at right angle to tht formed in meiosis 1

Question 13

3 types of genetic variation resulting from meiosis

Answer 13

1. random fusion of gametes
2. independent segregtion
3. crossing over in prophase 1

Question 14

how does random fusion of gametes produce genetic variation?

Answer 14

each parent cell is genetically unique and it is totally random which egg cell is fertilised by which sperm cell. at fertilisation, the zygote will have a totally unique combination of alleles

Question 15

why does crossing over occur in phrophase 1?

Answer 15

bivalents are so close when condensing (supercoiling) so the can get tangled

Question 16

4 steps of crossing over in prophase 1

Answer 16

1. chromosomes condense and tangle
2. non-sister chromatids cross over orming chiasmata
3. if alleles of gene at chiasma are differnt, genetic info is swapped
4. each chromosome involved is now recombinant

Question 18

chiasma

Answer 18

point at which crossing over has occurred in prohase 1

Question 19

recombinant

Answer 19

a cell or organism whose genetical material was produced when segements of DNA from different sources are joined

Question 20

non-disjunction

Answer 20

failure of homologous chromosomes to separate in meiosis

Question 21

recombination in chrossing over

Answer 21

each chromosome involved in crossing over has a new combnation of alleles that wasn’t present in either parent

Question 22

condensing of chromosomes

Answer 22

chromatin coils and supercoils

Question 23

independent segregation stage of meiosis

Answer 23

metaphase 1

Question 24

independent segregation

Answer 24

radom alignment of bivalents in metaphase 1 (matter of chance which chromosome goes into which cell)

Question 25

formula for possible combinations of chromosomes in haploid gametes

Answer 25

2^n where n= haploid number/number of pairs

Question 26

formula for possible combinations of chromosomes after fertilisation

Answer 26

(2^n)^2

Question 27

why is genetic diversity important?

Answer 27

greater genetic diversity means more likely some individuals in a population will survive an environmental change because a wider range of alleles means a wider range of chanracteristics.
w/o genetic diversity, natural selection could not occur

Question 28

genetic diversity

Answer 28

total number of different alleles in a population
greater numebr of alleles = greater genetic diversity