Cell Division and Cell Death

Question 1

How is cell division controlled

Answer 1

Cell Cycle

Question 2

What powers cell cycle

Answer 2

Cyclin- dependen kinase (CDKs)

Question 3

what regulates CDKs

Answer 3

cyclins

Question 4

Cell cycle checkpoints

Answer 4

End of G1, During G2 and End of M

Question 5

What happens if the cel fails the cell cycle checkpoints

Answer 5

cell is arrested

Question 6

Checkpoint G1

Answer 6

restriction point
check for cell size and favourable environment conditions, checks for DNA damage

Question 7

Checkpoint G2

Answer 7

check for damage or unduplicated DNA, checks for unduplicated centrosomes

Question 8

Checkpoint M

Answer 8

checks that chromosomes are attached to mitotic spindle

Question 9

What can uncontrolled cell division lead to

Answer 9

Tumours, identically defective daughter cells

Question 10

Chromosome condensation

Answer 10

• DNA tightly packed into nucleosomes
• Prior to mitosis they become supercoiled
• then becomes inaccessible to proteins involved in replication

Question 11

Chromosome segregation

Answer 11

• mediated by mitotic spindle
• condensed chromosomes attach to microtubules which radiate from the two centrosomes

Question 12

Phases of mitosis

Answer 12

Interphase, Prophase, Prometaphase, Metaphase, Anaphase, Telophase

Question 13

1. Interphase

Answer 13

During S phase, the nucleus replicates its DNA and centrosomes

Question 14

2. Prophase

Answer 14

= condenses into chromosome
- chromosome contains sister chromatid
- centrosomes move to opposite poles

Question 15

3. Prometaphase

Answer 15

nuclear envelope breaks down
- kinetochore microtubules appear and connect to kinetochores to the poles

Question 16

4. Metaphase

Answer 16

centrosomes align in a plane at equator

Question 17

5. Anaphase

Answer 17

paired sister chromatids separate
- new daughter chromosomes begin to move toward the poles

Question 18

6. Telophase

Answer 18

daughter chromosomes reach poles
- nuclear envelopes and nucleoli reform
- cytokinesis
- repeat

Question 19

Acto- myosin ring

Answer 19

contraction drives cytokinesis

Question 20

Types of cell death

Answer 20

Apoptosis
Autophagic cell death
Necroptosis
Necrosis

Question 21

Necrosis

Answer 21

• caused by cell damaging agents
• no energy required
• cell swelling and lysis
• generates inflammatory response

Question 22

apoptosis

Answer 22

• cell suicide
• cell contents are not released
• DNA and proteins broken down
• Dying cells engulfed by phagocytic cells
• no inflammatory response

Question 23

Apoptosis morphology

Answer 23

• cell condensation
• membrane bedding
• nuclear shrinkage
• chromatin condensation and fragmentation
• formation of apoptosis bodies

Question 24

Functions of Apoptosis

Answer 24

• regulating cell number by balancing cell division
• developmental process
• removal of phcagogenic cells

Question 25

Two distinct classes of caspases

Answer 25

Initiator
Executor

Question 26

Initiator caspases

Answer 26

activated by pro-apoptotic stimuli
- cleave and activate executor caspases
8,9,10

Question 27

Executor caspases

Answer 27

activated by inhibitor caspases
- cleave a variety of target proteins resulting in execution of apoptosis
3,6,7

Question 28

Role of mitochondria in apoptosis

Answer 28

Opening of pores in mitochondria outer membrane tiggers cytochrome C release and caspase activation

Question 29

Role of Bcl-2 in apoptosis

Answer 29

prevents the formation of pores in the mitochondrial out membrane
- the cell must over come this to activate programmed cell death pathways