1.5 protein control of cell division

Question 1

role of the cytoskeleton

Answer 1

gives mechanical support and shape to cells

Question 2

microtubules

Answer 2

hollow cylinders made of tubulin
make up the cytoskeleton
control movement of membrane-bound organelle

Question 3

where microtubules radiate from

Answer 3

microtubule organising centre (MTOC)

Question 4

polymerisation

Answer 4

formation of microtubules

Question 5

depolymerisation

Answer 5

breakdown of microtubules

Question 6

interphase

Answer 6

G1 growth
S DNA replication
G2 further growth

Question 7

mitotic phase

Answer 7

prophase
metaphase
anaphase
telophase

Question 8

prophase

Answer 8

DNA condenses into chromosomes of two sister chromatids
breakdown of nuclear membrane
spindle microtubules polymerise from MTOC and attach to chromosomes at their kinetochores

Question 9

metaphase

Answer 9

chromosomes are aligned at the metaphase plate (equator)

Question 10

anaphase

Answer 10

spindle fibres depolymerise
sister chromatids are separated and pulled to opposite poles

Question 11

telophase

Answer 11

chromosomes decondense and nuclear membrane forms around them

Question 12

define checkpoint

Answer 12

mechanisms that assess the condition of the cell during the cell cycle
halt progression to the next phase until certain requirements are met

Question 13

purpose of cyclin-CDK

Answer 13

phosphorylate proteins that regulate the cycle
upon sufficient phosphorylation, the cycle progresses

Question 14

retinoblastoma

Answer 14

protein which acts as a tumour suppressor by inhibiting transcription of genes that code for proteins needed for DNA replication

Question 15

G1 checkpoint

Answer 15

phosphorylation by G1 cyclic-CDK inhibits Rb
allows transcription of genes that code for proteins needed for DNA replication

Question 16

G2 checkpoint

Answer 16

assesses DNA replication and DNA damage
detection of damage triggers activation of proteins including p53

Question 17

role of p53

Answer 17

stimulate DNA repair
arrest the cell cycle
cause cell death

Question 18

metaphase checkpoint

Answer 18

progression is halted until the chromosomes are aligned correctly on the metaphase plate and are attached to spindle microtubules

Question 19

reduction in rate of the cell cycle

Answer 19

may result in degenerative disease

Question 20

increase in rate of the cell cycle

Answer 20

may result in tumour formation

Question 21

proto-oncogene

Answer 21

involved in controlling cell growth/division
can mutate to form a tumour-promoting oncogene

Question 22

apoptosis is triggered by

Answer 22

external/internal cell death signals
may initiate in the absence of growth factors

Question 23

example of external death signals

Answer 23

production of death signals from lymphocytes

Question 24

example of internal death signals

Answer 24

DNA damage

Question 25

how external death signals work

Answer 25

bind to surface receptor and trigger a protein cascade within the cytoplasm activation of caspases (protease enzyme)

Question 26

how internal death signals work

Answer 26

(resulting from DNA damage) activate p53 tumour-suppressor protein activation of caspases (protease enzyme)