chapter 3 part i (mitosis)

Question 1

what is cell division regulated by?

Answer 1

control of the cell cycle

Question 2

cell cycles of all _________ are similar.

Answer 2

eukaryotes

Question 3

what are the two main parts of the cell cycle

Answer 3

M phase; mitosis= cell divides
-interphase: the time between M phases(longer than M phase)

Question 4

Gap 1 (g1) phase

Answer 4

all proteins for normal cell functions are transcribed & translated (duration of G1 varies for different cell types)

Question 5

Gap 0 is also called the…

Answer 5

resting phase- differentiated cells

Question 6

what is G0

Answer 6

-some cells enter G0 after G1
-cells in G0 rarely re-enter the cell cycle

Question 7

when is S phase

Answer 7

(synthesis phase) after G1

Question 8

what is S phase

Answer 8

-when the DNA is replicated
-2 sister chromatids are produced for each chromosome

Question 9

Gap 2

Answer 9

-when cells prepare for division

Question 10

how many stages is M phase divided into?

Answer 10

5

Question 11

what are the stages of M phase

Answer 11

-prophase, prometaphase, metaphase, anaphase, telophase

Question 12

what does M phase accomplish?

Answer 12

-karyokinesis -dividing the DNA
-cytokinesis- dividing the cell/cytoplasm

Question 13

what are cells at the beginning of mitosis?

Answer 13

diploid (2n)
-s phase has recently completed duplicating each chromosome
-each chromosome is now composed of two identical sister chromatids
-amount of genetic material in the cell is doubled

Question 14

when does the condensation of chromosomes hit a maximum?

Answer 14

in metaphase

Question 15

what are centromeres

Answer 15

specialized sequences where sister chromatids are joined, become visible in prohase

Question 16

what do centromeres bind?

Answer 16

protein complexes called kinethechores

Question 17

during S-phase each chromosome is replicated, producing what?

Answer 17

sister chromatids which remain attached at the centromere (in the middle little x part) until anaphase

Question 18

while the chromatids are attached, what are the considered?

Answer 18

a single chromosome, just double the DNA. they are also called “replicated/duplicated chromosome”

Question 19

in animal cells, what do the two centromeres do?

Answer 19

they migrate to form the opposite poles of the cell

Question 20

centromeres nucleate spindle fiber microtubules where…

Answer 20

the minus end is at the centrosome, while plus end grows towards the kinetochores

Question 21

what pattern do the spindle fibers emanate from the centrosome in?

Answer 21

aster pattern

Question 22

what are the types of microtubules in cells?

Answer 22

-kinetochore microtubules
-polar microtubules
-astral microtubules

Question 23

describe kinetochore microtubules

Answer 23

-centrosome to kinetochores
-move chromosomes during cell division

Question 24

describe polar microtubules

Answer 24

-centrosome to centrosome
-cell elongation & stability
-AKA - non-kinetochore microtubules

Question 25

astral microtubules

Answer 25

-centrosome to membrane
-cell stability & shape

Question 26

what does sister chromatid cohesion do?

Answer 26

it balances the tension created by the pull of the kinetochore microtubules

Question 27

what is cohesion?

Answer 27

-a 4-subunit protein complex
- coats sister chromatids along their length
-highest concentration at centromeres
-holds sister chromatids together
-prevents their premature separation

Question 28

what happens in anaphase

Answer 28

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

Question 29

why do sister chromatids separate in anaphase?

Answer 29

it is due to the enzyme Separase.
-separase cleaves Scc1, a central component of the cohesion comples
-causes disjunction (seperation of sister chromatids)

Question 30

what is non-disjunction?

Answer 30

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

Question 31

in anaphase, what do the polar microtubules do?

Answer 31

they extend in length, so the cell elongated which allows cytokinesis

Question 32

in anaphase, what do the kinetochore microtubules do?

Answer 32

they shorter
-depolymerize their + end, moving individual chromatids toward the centrioles
-this draws chromosomes toward opposite poles

Question 33

what happens in telophase?

Answer 33

nuclear membranes reassemble around the chromosomes at each pole
-chromosomes de-condense to their diffuse interphase state
-two identical nuclei (each 2n) occupy the elongated cell, which will soon divide into two daughter cells through cytokinesis

Question 34

cytokinesis in animal cells

Answer 34

contractile ring of actin created a cleavage furrow around the outside of the cell which pinches the cell in two
-it begins on the edges & moves inward

Question 35

cytokinesis in plants

Answer 35

• a new cell wall is constructed along the cellular midline, called the cell plate
  -begins in the middle & moves outward

Question 36

what does cytokinesis do in both animal & plant cells?

Answer 36

it divides the cytoplasm & organelles between the daughter cells

Question 37

what does mitosis produce

Answer 37

• identical daughter cells
• two daughter cells are genetically identical
• mitosis separates copies of sister chromatids into identical nuclei
• the diploid number of chromosomes (2n) in maintained throughout the cell cycle

Question 38

cell cycle checkpoints

Answer 38

monitored by protein interactions for readiness to progress to the next stage

Question 39

what is cancer often characterized by

Answer 39

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

Question 40

mutations altering normal cell cycle controls are linked to what

Answer 40

various cell growth abnormalities

Question 41

G1 checkpoint:

Answer 41

-cell size, nutrient availibility sufficient, if growth factors are present

Question 42

S phase checkpoint

Answer 42

-pass if DNA replication is complete & has been screened to remove base-pair mismatch error

Question 43

G2 checkpoint:

Answer 43

pass if cell size is adequate & chromosome replication is successfully completed

Question 44

metaphase checkpoint

Answer 44

• pass if all chromosomes are attached to mitotic spindle