Meiosis in detail -- Lecture 9

Question 1

phases of meiosis:

Answer 1

interphase (G1, S, G2)

meiosis I (reduction division)

interkinesis (a rest period)

meiosis II

Question 2

phases of meiosis:

after interphase…

Answer 2

1 diploid cell (2 chromatids/chromosome)

Question 3

phases of meiosis:

after meiosis I…

Answer 3

2 haploid cells (2 chromatids/chromosome)

homologous chromosomes are segregated

Question 4

phases of meiosis:

after meiosis II…

Answer 4

4 haploid cells (1 chromatid/chromosome)

sister chromatids are segregated

Question 5

prophase 1 events:

Answer 5

1) chromosomes condense
2) nuclear membrane breaks down
3) spindle poles begin to form
4) homologous chromosomes pair up and are held together by synaptonemal complex proteins –> form a complex called a bivalent or tetrad

Question 6

crossing over during meiosis 1:

crossing over: in a ___, genetic material can be exchanged b/n paired chromosomes

Answer 6

bivalent

Question 7

crossing over during meiosis 1:

crossing over: in a bivalent, ___ can be exchanged b/n paired chromosomes

Answer 7

genetic material

Question 8

crossing over during meiosis 1:

crossing over: in a bivalent, genetic material can be ___ b/n paired chromosomes

Answer 8

exchanged

Question 9

crossing over during meiosis 1:

crossing over: in a bivalent, genetic material can be exchanged b/n ___

Answer 9

paired chromosomes

Question 10

crossing over during meiosis 1:

crossing over rearranges chromosomes and increases ___

Answer 10

genetic variation

Question 11

crossing over during meiosis 1:

may occur ___ times along chromosomes

Answer 11

multiple

Question 12

crossing over during meiosis 1:

only occurs during ___ when homologs are paired

Answer 12

prophase 1

Question 13

crossing over during meiosis 1:

only occurs during prophase 1 when ___ are paired

Answer 13

homologs

Question 14

crossing over during meiosis 1:

only occurs during prophase 1 when homologs are ___

Answer 14

paired

Question 15

metaphase 1:

Answer 15

homologous pairs line up at metaphase plate

Question 16

metaphase 1:

alignment of homologs on either side of the metaphase plate is ___

Answer 16

random

Question 17

metaphase 1:

independent assortment (what does it do)

Answer 17

ensures each new cell contains a mixture of homologs from the mother and father –> leads to greater genetic diversity

Question 18

anaphase 1:

events

Answer 18

synaptonemal complex proteins dissolve

homologs separate

homologs are segregated to opposite spindle poles by kinetochore microtubules

Question 19

anaphase 1:

homologs are segregated to opposite spindle poles by ___

Answer 19

kinetochore microtubules

Question 20

telophase 1:

events

Answer 20

chromosomes begin to decondense
spindle network breaks down
nuclear membranes re-form

Question 21

during/after telophase 1:

cytokinesis…

meiosis 1…

interkinesis…

Answer 21

cytokinesis divides the cell

meiosis 1 is completed

interkinesis occurs

Question 22

interkinesis (definition)

Answer 22

period of rest after meiosis 1 in preparation for meiosis 2

Question 23

meiosis 1 (features/review)

Answer 23

cell goes thru PMAT 1

homologs pair up during prophase 1 (bivalents)

bivalents held together by synaptonemal complex proteins

exchange of DNA occurs b/n homologs (crossing over)

homologous pairs align in metaphase I (independent assortment)

homologs separate and are segregated in Anaphase 1

telophase I and cytokinesis occur

result is 2 haploid cells (2 chromatids per chromosome)

interkinesis: period of rest before meiosis II

Question 24

meiosis I results in…

Answer 24

2 haploid cels (2 chromatids per chromosome)

Question 25

meiosis 2 – summary

how many (haploid/diploid) cells at the beginning of meiosis 2 (# chromatids per chromosome)?

does DNA replication occur in meiosis II?

Answer 25

2 haploid cells at the beginning of meiosis II (2 chromatids per chromosome)

no DNA replication in meiosis II

Question 26

meiosis 2 overview:

Answer 26

cell goes thru PMAT II

sister chromatids segregate during anaphase II

telophase II and cytokinesis occur

result is 4 haploid cells (1 chromatid per chromosome)

Question 27

haploid/diploid and chromatid # game:

cell prior to S-phase

Answer 27

diploid

1-chromatid chromosomes

Question 28

haploid/diploid and chromatid # game:

after S-phase but prior to Meiosis I

Answer 28

diploid

2-chromatid chromosomes

Question 29

haploid/diploid and chromatid # game:

after Meiosis I prior to Meiosis II

Answer 29

haploid

2-chromatid chromosomes

Question 30

haploid/diploid and chromatid # game:

after Meiosis II

Answer 30

haploid

1-chromatid chromosomes

Question 31

meiosis/mitosis combine to generate life

Answer 31

meiosis produces haploid ovum

meiosis produces haploid sperm

fertilization produces diploid zygote

mitosis produces whole organism