CMB1004/L05 Cell Cycle

Question 1

What are the products of meiosis?

Answer 1

4 genetically different haploid daughter cells

Question 2

What are the products of mitosis?

Answer 2

2 genetically identical diploid daughter cells

Question 3

In prokaryotes, what are the 2 phases of binary fission?

Answer 3

Replication & Division

Question 4

In eukaryotes, what are the 4 phases of mitosis?

Answer 4

Mitosis & Cytokinesis
Synthesis
Gap phase
Interphase

Question 5

Give the 6 stages of M phase.

Answer 5

Prophase
Prometaphase
Metaphase
Anaphase
Telophase
Cytokinesis

Question 6

What occurs during Prophase in mitosis? (2)

Answer 6

Mitotic spindle replicated and moved apart
Condensing and replication of chromosomes

Question 7

What occurs during Prometaphase in mitosis? (2)

Answer 7

Nuclear envelope breaks down
Centrosomes at spindle pole and begin to bond to chromosomes

Question 8

What occurs during Metaphase in mitosis? (2)

Answer 8

Sister chromatids align at spindle equator
Microtubules pull DNA to opposite poles of cell

Question 9

What occurs during Anaphase in mitosis?

Answer 9

Sister chromatids pulled apart to form daughter chromosomes, separated and pulled to opposite poles of the cell

Question 10

What occurs during Telophase in mitosis? (3)

Answer 10

Contractile ring contracts
Nuclear envelope begins to form
Daughter chromosomes decondense

Question 11

What occurs during Cytokinesis in mitosis? (4)

Answer 11

Contractile ring creates cleavage furrow
Nuclear envelopes complete
Actin & myosin pinch membrane
Reformation of interphase microtubules

Question 12

What occurs during interphase? (3)

Answer 12

Cell growth
Gene transcription
Protein synthesis

Question 13

What occurs during G1? (1)

Answer 13

Main growth
Checkpoint

Question 14

What occurs during S phase?

Answer 14

DNA synthesis

Question 15

What occurs during G2? (1)

Answer 15

Growth and final preparation
Checkpoint

Question 16

Name the 3 checkpoints of mitosis.

Answer 16

G1, G2 & M

Question 17

What internal factor regulates checkpoints in mitosis?

Answer 17

Growth factors (GFs)

Question 18

What external factors regulate checkpoints in mitosis? (2)

Answer 18

Density-dependent inhibition
Anchorage replication

Question 19

What are checkpoints in mitosis controlled by?

Answer 19

Cyclin-dependent kinases (Cdk)

Question 20

What signals that a cell is ready to proceed to the next phase in mitosis?

Answer 20

Phosphorylation

Question 21

What is quiescence?

Answer 21

Absence of proliferation signals in cells

Question 22

What occurs in mammalian cells with no signals? (2)

Answer 22

Enter G0
Apoptosis

Question 23

What occurs during G0?

Answer 23

Maintenance only

Question 24

What causes the most variation in frequency of cell division?

Answer 24

Time in G0/G1

Question 25

Give 2 examples of growth factors.

Answer 25

Platelet-derived growth factor Fibroblast growth factor Epidermal growth factor

Question 26

What concentration of growth factor is required for mitosis?

Answer 26

10^-10M

Question 27

Lack of what molecule causes cells to enter G0?

Answer 27

Growth factor

Question 28

When is apoptosis triggered? (2)

Answer 28

Physiologic activation Pathogenic activation

Question 29

Give 2 examples of physiologic activation of apoptosis.

Answer 29

Embryonic development Removal/remodelling of tissues Maintenance of homeostasis Control cell numbers

Question 30

Give 2 examples of pathogenic activation of apoptosis.

Answer 30

Viral infection Heat shock/toxins Removal of stressed/damaged cells

Question 31

What kind of signals can activate apoptosis? (2)

Answer 31

Hormonal signals Direct signals from contacting cells

Question 32

What 2 things can suppress apoptosis?

Answer 32

Survival factors Contact with extracellular matrix

Question 33

What is gene p53?

Answer 33

Transcription factor that increases apoptosis genes

Question 34

What 3 key events occur during apoptosis?

Answer 34

Activation of gene p53 Mitochondria become leaky and release cytochrome C Activation of caspases

Question 35

What causes gene p53 to activate?

Answer 35

DNA damage

Question 36

Which checkpoint do cells with activated p53 become blocked at?

Answer 36

G1

Question 37

What does the caspase cascade lead to? (2)

Answer 37

Activation of Dnase Cleavage of lamins and cytoskeleton

Question 38

What 3 functions do caspases have?

Answer 38

Cleaving of nuclear lamins Activation of DNase Cleave cytoskeleton

Question 39

What is necrosis?

Answer 39

Accidental cell death due to injury

Question 40

What occurs during necrosis? (3)

Answer 40

Nuclear swelling Cell membrane becomes leaky Lysis & cell contents released

Question 41

What bodily response is caused by necrosis?

Answer 41

Inflammation