The Cell Cycle

Question 1

The cell cycle

Answer 1

An ordered series of event that lead to division of a cell into two identical daughter cells

Question 2

M - mitosis

Answer 2

Segregation of chromosomes, followed by division to produce two daughter cells

Question 3

G1 - gap 1

Answer 3

Increase in cell contents including replication machinery

Question 4

S - synthesis

Answer 4

Replication of DNA —> chromosomes become two sister chromatids attached to the centromere

Question 5

G2 - gap 2

Answer 5

Preparation for division process

Question 6

G0

Answer 6

Cell not going through the cell cycle - arrested at G1

Question 7

Prophase

Answer 7

• chromosomes condensation
• dispersal of nucleoli
• separation of centrosomes and formation of mitotic spindle

Question 8

Prometaphase

Answer 8

• fragmentation of the nuclear envelope
• attachment of spindle MTs to centromeres
• chromosomes start to move towards cell centre

Question 9

Metaphase

Answer 9

Chromosome alignment at metaphase plate

Question 10

Anaphase

Answer 10

Chromosome (chromatids) move to opposite cell poles

Question 11

Telophase

Answer 11

• chromosome uncoil
• nucleoli develop and fuse
• disassembly of spindle
• re-formation of the nuclear envelope

Question 12

Kinetochore MTs

Answer 12

Move chromatids towards centrosome - Anaphase A

Question 13

Polar and astral MTs

Answer 13

Move poles away from each other (Anaphase B)

Question 14

What controls the cell cycle

Answer 14

1. Ensure processes happen in the right order
2. Sense and respond to signals
3. Monitor status and take decisions: progress or arrest

Question 15

Transition point

Answer 15

Cell controls progression of the cell cycle

Question 16

What do checkpoint pathways do?

Answer 16

Molecular pathways that monitor and stop cycle

Question 17

G0 —> G1

Answer 17

Growth factor signalling

Question 18

G1 —> S

Answer 18

Growth factors, nutrients, DNA damage checkpoint

Question 19

G2 —> M

Answer 19

DNA replication checkpoint; DNA damage checkpoint

Question 20

M —> G1

Answer 20

Mitotic spindle assembly checkpoint

Question 21

Mitotic spindle checkpoint

Answer 21

Prevents anaphase from beginning before chromosomes are all attached to the spindle

Question 22

DNA replication checkpoint

Answer 22

Monitors DNA replication to ensure DNA synthesis is completed before mitosis begins

Question 23

DNA damage checkpoints

Answer 23

Prevents cell with damaged DNA from proceeding through the cycle unless the damage is repaired

Question 24

DNA damage checkpoints

Answer 24

1. DNA damage activates
2. ATM/ATR phosphorylates checkpoint kinase
3. Checkpoint kinases phosphorylate p53, detach it from Mdm2 abd stabilize jt
4. p53 is a transcription factor

Question 25

Replicating challenges

Answer 25

• replicating the genetic information with high fidelity

- distributing chromosomes equally between daughter cells

Question 26

Chromatid cohesion

Answer 26

• each pair of sister chromatids are held together by proteins called cohesins
• the chromatids are held together until ready for separation during late mitosis

Question 27

Why is chrosome spindle attachment necessary?

Answer 27

For progression at anaphase

Question 28

What is Cdc20?

Answer 28

A kinase that acts as an activator of the anaphase promoting complex

Question 29

What do cyclin-CDK complexes do?

Answer 29

Ensure processes happen in the right order

Question 30

What do external and internal signals do?

Answer 30

Sense and response to signals

Question 31

What does chromatid cohesion do?

Answer 31

Prevents uncontrolled segregation of replicated chromosomes