*RPB L5- Cell Survival Curves Flashcards

1
Q

What does “clonogenic” mean?

A

Think of it as “Clone”- means that a cell is able to replicate itself… proliferate indefinitely

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What does “reproductive death” mean?

A

For cells that can no longer grow - they are technically still ‘alive’, however they are DEAD as they cannot replicate anymore

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What does “proliferate” mean?

A

Able to divide (in this case, replicate) indefinitely

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What factors affect the shape of the curve?

A

OER, LET, cell cycle, cell type, total dose, dose rate…

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the x and y axis on the cell survival curve?

A

x: dose rate, y is cell survival in LOG (so we can get a linear line)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Why is the cell survival semi-log??

A

Semi-log scale because we want our line to be linear - easier for calculations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How much dose do you need to destroy
1. non-proliferating cells
2. proliferating cells
Explain why

A
  1. 100Gy
  2. 2Gy
    Because dividing/growing cells are more radiosensitive than non-growing cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

You saw how when there is DNA damage, you can have the sticky ends joining, or you can have diccentric rings; can these still replicate?

A

NO!

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the difference between in vitro and in vivo?

A

Vivo is inside organism, vitro is like in petri dish

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the relationship between dose and survival? (i.e. linear, cubic, quad, log…)

A

LINEAR: Increase dose, decrease cell survival

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is “plating efficiency”?

A

Exactly what it sounds like - how efficient the ‘plate’ is - glass plate maybe?

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is surviving fraction?

A

How many cells survived after radiation (on the petri disk); there is a formula for this

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the three types of results of radiation damage?

A
  1. Sublethal
  2. Lethal
  3. Potentially lethal
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is lethal DNA damage?

A

Cannot be reversed. It’s gone!

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Where does radiation usually target?

A

DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is mitotic death?

A

Death of the cell when it tries to divide - has lost its proliferative ability

17
Q

What is sub-lethal damage?

A

Damage that can be repaired, if given time

18
Q

What is potentially lethal damage?

A

Depends on environment - depends on the post-environmental conditions i.e. Giving oxygen

19
Q

What is the shape of the survival curve for densely ionising radiation and sparsely ionising radiation?

A

Dense would be very steep, no shoulder, straight down. Sparse would have a shoulder, mix of quadratic and linear line

20
Q

What is Dq?

A

QUASITHRESHOLD - the ‘threshold’ where no damaging is taking place up until this dose threshold

21
Q

Cell survival curve: It is both linear and quadratic. What do they represent?

A

Linear part is when there is 1 irradiation event that breaks both DNA strand. Quadratic is related to breaks due to 2 separate events - Think of it as like Linear = alpha, str8 kill

22
Q

Is high or low LET curve a straight line? Why?

A

High - More Linear Energy Transfer means more damage done = i.e. alpha particle is linear line

23
Q

Does sparse or dense ionising radiation have a linear curve?

A

DENSE

24
Q

If you were given x-rays, neutrons and alpha particles, which one would be steepest to least steep in survival curve?

A

alpha steepest, neutrons middle, x-rays least steep

25
Q

In the survival curve formula, can you actually tell which DNa is getting hit by alpha/which getting hit by beta?

A

No, this formula is kinda just a mathematical formula for us to use

26
Q

Define Quasithreshold

A

Dq is the dose at which the linear portion of the survival curve, extrapolated backward, cuts the dose axis drawn through a survival fraction of unity (100%)

27
Q

What is extrapolation number?

A

this is ‘n’; tells us about the shoulder of the curve. It is the width of the shoulder. If n is large, shoulder is broad

28
Q

How do you find D0 on graph?

A

CHOOSE A LINEAR PART!! Doesn’t matter where, just choose a part and go to approx 37%

29
Q

What does it mean if you see the cell survival curve with lots of repeated shoulders?

A

FRACTIONATION of dose

30
Q

What is the “bystander effect”?

A

It is when cells closeby to those cells that are directly irradiated by a charged particle gets damaged

31
Q

When is the bystander effect most pronounced?

A

When the cells are joined by gap-junctions: 30% bystander cells will die

32
Q

What is apoptosis and mitotic death?

A

You know this already!

33
Q

What is AUTOPHAGY? How is it different from apoptosis?

A

AUTOPHAGY - self eating: using lysosomes. apoptosis is programmed cell death.
Autophagy is a type (2) of apoptosis

34
Q

What is senescence? What protein is involved?

A

A type of cell death - when the cell is stressed out… p53 and Rb (Rubbish bin… lol) and 53kg…

35
Q

If a response to radiation is expected, no matter how small the dose, then that dose-response is _____.
Threshold or non-threshold?

A

non-threshold; like alpha particles?

36
Q

Radiation induced genetic damage follows a _____ dose-response relationship.
Linear-non-threshold or linear-threshold

A

Linear non-threshold

37
Q

In a linear qudratic model, is alpha or beta constant smaller?

A

Beta- because alpha is more steep

38
Q

The mean probability of one particle causing a lesion is linearly proportional to dose

A

True