The cell cycle

Question 1

What is required to prevent the introduction of serious errors during cell number expansion?

Answer 1

Coordination mechanism

Question 2

What are the 3 critical events that need to occur during the cell cycle?

Answer 2

1. Chromosome replication
2. Chromosome segregation
3. Cell division

Question 3

What do almost all normal cells require in order to proliferate?

Answer 3

Extrinsic factors

Question 4

What type of proteins can overrule stimulatory factors & force proliferation to a halt?

Answer 4

Signalling proteins

Question 5

What is the master governor that makes the major decisions regarding the cell fate?

Answer 5

Cell cycle clock (operates in the nucleus)

Question 6

What are the 2 process that the cell cycle clock can encourage?

Answer 6

Division or the prevention of replication (sent into G0 or quiescent state)

Question 7

What are the 5 stages of the cell cycle?

Answer 7

Prophase
Prometaphase
Metaphase
Anaphase
Telophase

Question 8

What occurs during prophase?

Answer 8

movement of the centrioles to polar end of the nucleus, condensation of chromosomes

Question 9

What occurs during prometaphase?

Answer 9

components of the mitotically spindle elongate away from the spindle poles

Question 10

What occurs during metaphase?

Answer 10

chromosome alignment is complete

Question 11

What occurs during anaphase?

Answer 11

pairs of sister chromatids are separated

Question 12

What occurs during telophase?

Answer 12

chromosomes start to de-condense, nuclear membrane starts to be re-established.

Question 13

When is chromatin de-condensed?

Answer 13

when the cell is not dividing (de-condenses after telophase)

Question 14

Describe the parts of interphase

Answer 14

G1, S (synthesis phase), G2, M (mitotic phase)

Question 15

What occurs during G1?

Answer 15

• cell increases in size
• ribosomes, RNA produced
• preparation for DNA synthesis
• where the cell responds to signals

Question 16

What occurs during the S stage?

Answer 16

DNA synthesised (chromosome duplicated)

Question 17

What occurs during the G2 phase?

Answer 17

• cell checks for fidelity of DNA
• preparation for nuclear division

Question 18

What stage during interphase takes the longest time?

Answer 18

G1 takes the longest duration

Question 19

What occurs if a cell enters G0?

Answer 19

They will not divide & not grow. They can re-enter the cycle from G0?

Question 20

What process actually occurs during G0 phase?

Answer 20

cytokine removal can occur - from G1 to G2

Question 21

What is the purpose of checkpoints?

Answer 21

• allows for increase to scheduled length of a phase.
• facilitates repair processes

Question 22

What occurs at the G1 checkpoint (end of G1)?

Answer 22

checks for DNA damage & may rectify situation if problem is detected?

Question 23

What occurs at the G2 checkpoint?

Answer 23

check for damage or if DNA replication is incomplete

Question 24

What occurs at the M checkpoint?

Answer 24

check for chromosomal attachment to spindle fibres

Question 25

The removal of what factors in the final hour of G1 allows for the transition into S, G2 & M phase?

Answer 25

serum & growth factors

Question 26

The deregulation of what point in the G1 phase can lead to cancer?

Answer 26

R point (point of no return), where cells are sensitive to cytokine withdrawal

Question 27

What staining is used to view cells at different stages of the cell cycle?

Answer 27

Diffuse staining

Question 28

What is the problem with using the genetic approach to look for genes that bring about a cell cycle transition?

Answer 28

Requires cells that have a mutation in a putative cell cycle transition gene

Question 29

What is the problem with using the genetic approach to look for genes that bring about a cell cycle transition?

Answer 29

requires supply large number of cells undertaking the same transition at the same time

Question 30

What is the advantage of using yeast as a genetic model for a cell cycle?

Answer 30

- rapid division rate (<1hr) - cell cycle control genes are highly conserved - yeast can be growth as haploid or diploids

Question 31

What are 2 genetic tricks allow identification of potentially lethal mutations?

Answer 31

- diploid can be used to maintain lethal mutations, that are then studied in haploid. - temperature sensitive mutations allow growth at permissive temperature

Question 32

What can be used to deplete the cytoplasm of different proteins during cell-free mitosis?

Answer 32

antibodies

Question 33

What is an example of hormonal activity causing the transition to M phase?

Answer 33

oocyte to egg transition

Question 34

What 2 classes of proteins must be present to allow transition from G2 to M?

Answer 34

cyclin & cyclin-dependent kinases (have to exist as a complex)

Question 35

What are protein kinases?

Answer 35

signalling devices which operate to create molecular

Question 36

Does there seem to be a relationship between kinase activity & the cell cycle transitions?

Answer 36

YES

Question 37

What is the cell cycle regulator kinase called in yeast?

Answer 37

CDk1 (cyclin-dependent kinase 1), however there are multiple kinases

Question 38

How do yeast cells activate transition between different stages of the cell cycle?

Answer 38

The presence of different cyclins, paired with CDk1 (cyclin-dependent kinase 1)

Question 39

What 2 factors drive forward transition between different stages of the cell cycle?

Answer 39

Cyclin/CDKs

Question 40

What type of cyclins are controlled by extracellular signals?

Answer 40

D-type cyclins

Question 41

What can regulate the formation of cyclin/CDKs complexes?

Answer 41

CDK inhibitors (CKIs)