cell cycle

Question 1

overview of the cell cycle?

Answer 1

G1 - cell synthesis of proteins
S - DNA replication
G2 - gap phase
M - cell divides

Question 2

what happens to chromosomes in S and M?

Answer 2

in S, chromosomes are duplicated, in M, chromosomes are segregated into daughter nuclei

Question 3

what is flow cytometry?

Answer 3

it detects and analyzes chemical and physical characterizations of cells/particles
measures fluorescence cells
measure amount of DNA (using dye) to tell us cell cycle phase

Question 4

what are the checkpoints in the cell cycle?

Answer 4

G2 (entering M) - is DNA replicated and is environment favourable
metaphase (exiting M) - are all chromosomes attached to spindle
G1 (entering S) - is the environment favourable

Question 5

what happens to cyclin?

Answer 5

forms complex with Cdk (activates it) to trigger specific cell cycle events

Question 6

what is cdk terminated by?

Answer 6

cyclin degradation

Question 7

what are the three main cyclins?

Answer 7

G1/S-cyclins activate Cdks at end of G1 and commit cell to DNA replication
S-cyclins activate Cdks during S phase for DNA replication
M-cyclins promote mitosis
sometimes G1-cyclin is included (controls G1 start)

Question 8

what triggers final part of cell division?

Answer 8

protein destruction

Question 9

what is APC?

Answer 9

anaphase-promoting complex is activated during metaphase and promotes M-cyclin degradation

Question 10

what happens do chromosomes at the end of S?

Answer 10

they are a pair of chromatids held together by cohesin

Question 11

what is the biggest issue in M phase?

Answer 11

segregating its chromosomes

Question 12

what happens in prophase?

Answer 12

replicated chromosomes condense and mitotic spindle assembles outside nucleus

Question 13

what happens in prometaphase?

Answer 13

nuclear envelope breaks and microtubules attach to chromosomes at positive ends

Question 14

what happens in metaphse?

Answer 14

chromosomes align to spindle center Iastral and kinetochore make up the mitotic spindle

Question 15

what are the main kinesins?

Answer 15

kinesin-5 slides microtubules in opposite directions
kinesin-14 crosslinks antiparallel microtubules at center (moves one)
kinesin-4/10 are positive direction to push chromosomes to center

Question 16

what happens in anaphase?

Answer 16

sister chromotids become two chromosomes (spindle also moves)

Question 17

what are important sensors in anaphase?

Answer 17

aurora B (kinase force sensor) tells cell that chromosomes are orientated properly (if active = improper = low tension)
seperase (cysteine protease) triggers anaphase by hydrolysing cohesin

Question 18

what happens in telophase?

Answer 18

chromosomes arrive at poles, form new nuclear envelopes (end of mitosis and start of cytokinesis)

Question 19

what does cytokinesis do?

Answer 19

separates two cells using a contractile ring (actin and myosin)

Question 20

what happens if cytokinesis doesn’t happen?

Answer 20

cells have many nucleus called syncytium

Question 21

what happens if cytokinesis is incomplete?

Answer 21

cells connected by intercellular bridges

Question 22

what is endoreplication?

Answer 22

replicates nuclear genome in the absence of mitosis (leads to polyploidy)