ch. 3 mitosis

Question 1

what is cell division regulated by

Answer 1

control of cell cycle

Question 2

cell cycles of all _____________ are similar

Answer 2

eukaryotes

Question 3

2 main parts of cell cycle

Answer 3

1. M phase - mitosis, cell divides
2. interphase - time between M phases

Question 4

subphrases of interphase

Answer 4

1. Gap 1 (G1)
2. Resting phase (G0)
3. S phase
4. Gap 2 (G2)

Question 5

Gap 1 phase

Answer 5

• all proteins for normal cell function are transcribed and translated

Question 6

G0 phase

Answer 6

• differentiated cells
• some cells enter G0 after G1

Question 7

do cells in G0 reenter cell cycle?

Answer 7

no - rarely

Question 8

S phase

Answer 8

• DNA is replicated
• 2 sister chromatids produced for each chromosome

Question 9

G2 phase

Answer 9

• cells prepare for division

Question 10

substages of M phase

Answer 10

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

Question 11

what does the M phase accomplish?

Answer 11

• karyokinesis
• cytokinesis

Question 12

karyokinesis

Answer 12

dividing the DNA

Question 13

cytokinesis

Answer 13

dividing the cell/cytoplasm

Question 14

are cells at the beginning of mitosis diploid or haploid?

Answer 14

diploid

Question 15

composition of chromosome after S phase

Answer 15

2 identical sister chromatids
- amount of genetic material doubled

Question 16

where does condensation of chromosomes begin

Answer 16

prophase

Question 17

where does maximum condensation of chromosomes occur

Answer 17

metaphse

Question 18

centromeres

Answer 18

specialized sequences where sister chromatids are joined

Question 19

what do centromeres bind?

Answer 19

protein complexes called kinetochores

Question 20

the moment two sister chromatids separate, they are considered…

Answer 20

2 separate chromosomes

Question 21

centrosomes

Answer 21

nucleate spindle fiber microtubules
- migrate to form opposite poles of dividing cell

Question 22

where are centrosomes found?

Answer 22

animal cells

Question 23

what end of the microtubule is at the centrosome?

Answer 23

minus (-)

Question 24

what end of the microtubule is at the kinetochores?

Answer 24

plus (+)

Question 25

aster

Answer 25

pattern in which spindle fibers emanate from the centrosomes

Question 26

types of microtubules in cells

Answer 26

1. kinetochore 2. polar 3. astral

Question 27

kinetochore microtubules

Answer 27

- centrosome to kinetochore - move chromosomes during cell division

Question 28

polar microtubules

Answer 28

- centrosome to centrosome - cell elongation and stability - "non-kinetochore microtubules"

Question 29

astral microtubules

Answer 29

- centrosome to membrane - cell stability and shape

Question 30

what does sister chromatid cohesin balance?

Answer 30

tension created by pull of kinetochore microtubules

Question 31

cohesin

Answer 31

4-subunit protein complex that coats sister chromatids along their entire length to hold them together - prevents premature separation

Question 32

where is highest concentration of cohesin?

Answer 32

centromeres

Question 33

what happens in anaphase?

Answer 33

sister chromatids separate and begin to move toward opposite poles in the cell

Question 34

what causes sister chromatids to separate in anaphase A?

Answer 34

action of enzyme Separase

Question 35

separase

Answer 35

cleaves Scc1, a central component of cohesin complex - causes disjunction

Question 36

disjunction

Answer 36

separation of sister chromatids

Question 37

non-disjunction

Answer 37

failure of sister chromatids to properly separate - causes chromosomal number mutations

Question 38

what do polar microtubules do during anaphase

Answer 38

extend in length, which will later allow cytokinesis

Question 39

what do kinetochore microtubules do during anaphase

Answer 39

shorten - depolymerize at their plus end, moving individual chromatids toward centrioles/opposite poles

Question 40

what happens in telophase

Answer 40

- nuclear membranes reassemble around chromosomes at each pole - chromosomes de-condense - 2 identical nuclei occupy elongated cell, which will soon undergo cytokinesis

Question 41

cytokinesis in animal cells

Answer 41

- contractile ring of actin creates cleavage furrow around circumference of cell - pinches cell in 2 - begins on edges and moves inward

Question 42

cytokinesis in plants

Answer 42

- new cell wall is constructed along cellular midline (cell plate) - begins in middle and moves outward

Question 43

what does mitosis produce?

Answer 43

2 identical daughter cells

Question 44

are the daughter cells genetically identical?

Answer 44

yes

Question 45

do cells ever become haploid during mitosis?

Answer 45

no

Question 46

cell cycle checkpoints

Answer 46

monitored by protein interactions for readiness to progress to next stage

Question 47

mutations altering normal cell cycle control are linked to what?

Answer 47

various cell growth abnormalities

Question 48

cancer is often characterized by what?

Answer 48

out-of-control proliferation of cells that can invade and displace normal cells

Question 49

G1 checkpoint

Answer 49

pass if: - cell size adequate - nutrient availability is sufficient - growth factors present

Question 50

S-phase checkpoint

Answer 50

pass if: - DNA replication is complete - screened to remove base-pair mismatch error

Question 51

G2 checkpoint

Answer 51

pass if: - cell size is adequate - chromosomes replication completed

Question 52

metaphase checkpoint

Answer 52

pass if: - all chromosomes attached to mitotic spindle