D2.1 Cell and Nuclear Division

Question 1

binary fission

Answer 1

reproduction in prokaryotes, DNA is copied and attaches to different regions on membrane, produces 2 identical diploid daughter cells

Question 2

mitosis

Answer 2

for growth/repair in multicellular cells, asexual reproduction in unicellular cells, DNA is copied and pulled to opposite sides for division, produces 2 identical diploid daughter cells

Question 3

meiosis

Answer 3

produces gametes, DNA is copied and pulled to opposite sides for first phase, pulled apart again for second phase, produces 4 haploid daughter cells with random combinations of genes

Question 4

cytokinesis in animal cells

Answer 4

contractile actin and myosin filaments make membrane pinch in to form cleavage furrow, which gets deeper to eventually split cytoplasm

Question 5

cytokinesis in plant cells

Answer 5

vesicles line up in middle and fuse with membrane to build cell plate, cellulose secreted inside to form cell wall and separate cytoplasm

Question 6

examples of unequal cell division

Answer 6

oogenesis (when 4 haploid eggs, 3 donate to make 1 big one, resulting in 3 unviable, small zygotes) and budding (when small daughter yeast cell closes off from parent)

Question 7

what gives microtubules their directionality?

Answer 7

a negative and positive end

Question 8

describe how microtubules pull apart sister chromatids

Answer 8

1. motor proteins “walk” along overlap microtubules, making them slide past each other
2. movement pushes centrosomes away
3. centrosomes connected to kinetocore microtubules, connected to kinetochores, connected to chromosome
4. chromatids pulled apart, microtubules recycled

Question 9

phases of mitosis

Answer 9

1. prophase
2. metaphase
3. anaphase
4. telophase

Question 10

prophase

Answer 10

chromosomes form, nuclear membrane dissolves, mitotic spindle form and attach to kinetochores, centrosomes move to opposite poles

Question 11

metaphase

Answer 11

chromosomes line up on metaphase plate

Question 12

anaphase

Answer 12

fibres pull chromatids to opposite poles, splitting centromere

Question 13

telophase

Answer 13

46 single chromosomes at each pole uncoil, nuclear membrane reforms, spindle disappears, cell elongates

Question 14

phases of meiosis 1

Answer 14

1. prophase 1
2. metaphase 1
3. anaphase 1
4. telophase 1
5. cytokinesis

Question 15

prophase 1

Answer 15

chromosomes formed and homologous become bivalents and cross over, nuclear membrane dissolves, spindle fibres form

Question 16

metaphase 1

Answer 16

bivalents line up on metaphase plate in random orientation

Question 17

anaphase 1

Answer 17

fibres attach to homologous chromosomes and pull to opposite poles

Question 18

telophase 1

Answer 18

23 double chromosomes at each pole uncoil, nuclear membrane reforms, spindle disappears, cell elongates

Question 19

cytokinesis 1

Answer 19

first split into 2, resulting into 2 haploid nuclei with 23 double chromosomes

Question 20

phases of meiosis 2

Answer 20

1. prophase 2
2. metaphase 2
3. anaphase 2
4. telophase 2

Question 21

prophase 2

Answer 21

chromosomes reform, nuclear membrane dissolves, spindle fibres reform

Question 22

metaphase 2

Answer 22

chromosomes line up on metaphase plate in random orientation, no pairs, fibres attach

Question 23

anaphase 2

Answer 23

fibres pull sister chromatids to opposite poles, splitting centromeres

Question 24

telophase 2

Answer 24

23 single chromosomes at each pole uncoil, nuclear membrane reforms, spindle disappears, cell elongates

Question 25

recombinant chromatids

Answer 25

non-sister chromatids that have gone through crossing over

Question 26

types of meristematic tissue

Answer 26

apical (root/branch tips, lengthening), lateral (stems, widening)

Question 27

what is cell proliferation and examples of where it occurs?

Answer 27

rapid dividing of cells; meristems, formation of zygotes

Question 28

cell cycle

Answer 28

1. G0 - during G1 or C, cell pause in non-growing state
2. G1 - growth, material accumulation
3. S - DNA replication
4. G2 - growth, mitochondria/chloroplast replication, DNA starts to coil, microtubules
5. M - mitosis
6. C - cytokinesis

Question 29

when are there checkpoints in the cell cycle?

Answer 29

restriction point during G1, DNA damage checkpoint during S and G2, spindle checkpoint during mitosis

Question 30

cyclin

Answer 30

protein controlling cell progression through cycle; binds to cyclin-dependent protein kinase and phosphorylates, activating enzyme to allow cell enter S and M phase

Question 31

oncogene

Answer 31

can accumulate/be expressed at abnormally high rates, modifies apoptosis, triggered by mutagen, causes cancer

Question 32

proto-oncogene

Answer 32

can become oncogene

Question 33

tumour surpressor genes

Answer 33

code for proteins that control cell cycle, apoptosis, repair; can be silenced/mutated by methyl

Question 34

mitotic index

Answer 34

ratio of cells in mitosis to total; under 14% is low, over 75% is cancerous