6. Cell proliferation and death

Question 1

what 2 things control cell proliferation

Answer 1

cell contact 
soluble signals (GF)

Question 2

increased proliferation achieved by (2)

Answer 2

1. shortening cell cycle

2. recruiting quiescent cells into the cell cycle

Question 3

3 types of cells in terms of dividing

Answer 3

1. labile
2. stable
3. permanent

Question 4

what are stable cells?

Answer 4

cells which have low levels of replication - only divide in response to stimuli

Question 5

examples of stable cells

Answer 5

hepatocytes

Question 6

examples of permanent cells

Answer 6

neurones

Question 7

what is hypertrophy

Answer 7

increase in cell size

Question 8

what is hyperplasia

Answer 8

increase in cell number

Question 9

1 physiological example of hypertrophy

Answer 9

increase in skeletal muscle in athletes

Question 10

2 pathological examples of hypertrophy

Answer 10

1) myocardium
2) arterial smooth muscle
due to hypertension

Question 11

3 physiological circumstances of hyperplasia

Answer 11

1. high altitude
2. preganncy
3. puberty

Question 12

example of hyperplasia

Answer 12

graves disease - of thyroid

Question 13

give a physiological example where both hypertrophy and hyperplasia occurs

Answer 13

uterine smooth muscle - in puberty and pregnancy

Question 14

3 main phases of cell cycle

Answer 14

Interphase
mitosis
G0 = terminally differentiated

Question 15

which phase occupies most of the cell cycle

Answer 15

interphase

Question 16

3 phases of interphase

Answer 16

g1
s
g2

Question 17

what occurs in G1

Answer 17

cells do their normal function - differentiate

Question 18

what occurs in S

Answer 18

DNA replication

Question 19

what occurs in G2

Answer 19

cells prepare for mitosis

Question 20

stages of mitosis

Answer 20

PMAT

Question 21

what occurs in prophase

Answer 21

• Ch become visible
• nucleoli dissapear
• nuclear membrane dissolves
• centriole migrates to opposite ends of cell
• spindle of microtubules form between centrioles

Question 22

what occurs in metaphase

Answer 22

• Duplicated Chs attach at centromere

- Ch line up on metaphase plate

Question 23

what occurs in anaphase

Answer 23

• chromatids pulled apart to opposite ends of spindle/cell

- centrioles pulled apart

Question 24

what occurs in telophase

Answer 24

• nucleoli reappear, nuclear envelope reforms
• cleavage forms
• cytokinesis; cells split

Question 25

what are the 4 main checkpoints

Answer 25

G1, S, G2, metaphase

Question 26

role of metaphase checkpoint

Answer 26

arrests phase if there is not correct assembly of ch - prevents unequal distribution of DNA in daughter cells

Question 27

which checkpoints are CDKs involved in

Answer 27

G1 and G2

Question 28

what does CDK stand for

Answer 28

cyclin dependent kinases

Question 29

function of CDKs

Answer 29

promote cell cycle progression for accurate DNA replication and mitosis

Question 30

describe how CDKs control cell cycle in 4 steps

Answer 30

1. CDK1+ cyclin B form inactive M-CDK 2. CAK adds an inhibitory and activating phosphate to inactive M-CDK 3. at the end of G2 - cdc25 activates the complex by removing the inhibitory phosphate 4. active M-CDK formed

Question 31

what are the 2 cell cycle regulators

Answer 31

p53 pRb

Question 32

in p53's inactive form - what is it attached to?

Answer 32

mdm2

Question 33

in pRb inactive form - what is it attached to?

Answer 33

phophorus

Question 34

describe in steps how p53 works

Answer 34

1. inactive = p53+mdm2 2. cell damage causes activation = p53 3. p53 acts as TF for p21 (CDK inhibitor) 4. cell cycle arrest 5. either repair or apoptosis

Question 35

describe in steps how pRb works

Answer 35

1. inactive = pRb + P 2. detects DNA damage (via CDK4 and Cyclin D) 3. activates and attaches to TF = pRb + E2F 4. blocks progression from G1 to S

Question 36

what does a mutation in p53 cause?

Answer 36

Li-Fraumani syndrome - cell stuck in cell cycle arrest

Question 37

what does a mutation in pRb cause?

Answer 37

retinoblastoma

Question 38

what is pRb?

Answer 38

tumour suppressor gene

Question 39

role of CDKIs

Answer 39

cell cycle arrest - allowing for either apoptosis or repair

Question 40

what do High GF control?

Answer 40

cell proliferation

Question 41

what do low GF control?

Answer 41

cell cycle arrest

Question 42

what do high oncogenes control?

Answer 42

cell proliferation

Question 43

what do high tumour suppressors control?

Answer 43

cell cycle arrest

Question 44

what do high ECM stiffness control?

Answer 44

cell proliferation

Question 45

what do low cell density control?

Answer 45

cell proliferation

Question 46

is necrosis passive or active?

Answer 46

passive

Question 47

is apoptosis passive or active?

Answer 47

active

Question 48

how many cells are destroyed in apoptosis?

Answer 48

single cells

Question 49

how manu cells are destroyed in necrosis?

Answer 49

cell groups

Question 50

what occurs to lysosomes in i) apoptosis ii) necrosis?

Answer 50

i) in tact ii) leak lytic enzymes

Question 51

difference betweeen cell membrane in cell apoptosis and necrosis

Answer 51

apop - maintained | nec - lost

Question 52

morphology of apoptosis

Answer 52

cell shrinkage and fragmentation to form apoptotic bodies

Question 53

morphology of necrosis

Answer 53

cellular swelling and lysis

Question 54

which cell death type involves inflammation; why?

Answer 54

only necrosis - neutrophils involved

Question 55

how are dead cells removed in i) apoptosis ii) necrosis?

Answer 55

phagocytosis in both i) macrophages ii) neutrophils and macrophages

Question 56

apoptosis is a part of i) normal homeostasis ii) disease process iii) both

Answer 56

both

Question 57

give 4 examples of apoptosis

Answer 57

1. programmed cell death 2. regulation of cell population + tumour suppression 3. neutrophil apoptosis - reducing inflammation 4. T cell mediated destruction of viral infected cell