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Radiographic Protection and Radiobiology > Radiation effects on DNA, Chromosomes and cells > Flashcards

Radiation effects on DNA, Chromosomes and cells Flashcards

1
Q

What are the three levels that biologic damage can be observed at?

A
  1. Molecular (DNA, RNA)
  2. Cellular (Cell structure)
  3. Organic level
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2
Q

Is molecular damage visible?

A

No, molecular damage is not visible under a microscope

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3
Q

At what level do we begin to see damge to an organism?

A

At the cellular level or organic level

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4
Q

T/F

Any visible radiation induced injuries at the cellular or organic level always begin with damage at the molecular level

A

True

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5
Q

What type of damage results in the formation of structurally changed molecules that may impair cellular functioning?

A

Molecular damage

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6
Q

What are the four categories of radiation effects on DNA?

A
  1. Base damage
  2. Single strand breaks
  3. Double strand breaks
  4. Crosslinks/crosslinking
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7
Q

What type of action causes the most damage to DNA?

A

Indirect action

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8
Q

What damage is this describing?

Change or a loss of base pairs

A

Base damage

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9
Q

What damage is this describing?

Break in the backbone of one chain of a DNA molecule

A

Single strand breaks

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10
Q

What damage is this describing?

Break in both chains of the DNA molecule

A

Double strand breaks

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11
Q

What damage is this describing?

Intrastrand or interstrand bases sticking together

A

Crosslinking

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12
Q

What are the three types of molecular damage to the DNA?

A
  1. Cross linking
  2. Main chain scission
  3. Point lesions
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13
Q

What are the 4 outcomes that a damaged DNA can cause?

A
  1. Cell repair
  2. Metabolic changed causing malignancies
  3. Cell death/organ/tissue damage
  4. Genetic damage to reproductive cells
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14
Q

What type(s) of action causes single strand breaks

A

Indirect and direct action (most likely indirect)

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15
Q

Is damage reversible with single strand breaks? If so, how?

A

Yes, repair enzymes are often capable of reversing the damage

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16
Q

If single strand breaks are unable to be repaired, what injury is likely to occur to the DNA?

A

Point lesions

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17
Q

What happens during a single strand break?

A

There is a transfer of energy which ruptures one of the molecules chemical bonds, severing one of the sugar phosphate chain side rails

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18
Q

Is damage reversible with double strand breaks? What makes damage easier to repair with double strand breaks?

A

-Yes, but not as easy as single strand breaks
-Damage is easier to repair if the breaks are far enough apart

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19
Q

What type of LET is more likely to cause double strand breaks?

A

High LET

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20
Q

If double strand breaks are unable to be repaired, what injury is likely to occur to the DNA?

A

-Further separation may occur in the DNA chains, threatening the life of the cell

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21
Q

What happens during a double strand break?

A

Further exposure to an affected DNA molecule can lead to additional breaks in the sugar-phosphate chain

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22
Q

What are the results from a double strand break in the same rung of DNA?

A

-Broken chromosome with an unequal amount of genetic material

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23
Q

What will occur if a damaged chromosome divides?

A

Each new daughter cell will recieve an incorrect amount of genetic material, resulting in cell death or impaired functioning

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24
Q

T/F

Single strand breaks are often repaired.

A

True

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25
Q

What action(s) is most likely to cause covalent cross inks?

A

Both direct and indirect action can cause covalent cross links

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26
Q

What occurs during cross linking?

A

Radiation can cause strands of DNA to attach to other macromolecules or to other segments of the same macromolecule chain

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27
Q

What damage occurs from crosslinking?

A

-Reproduction arrest and cell death if not repaired

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28
Q

What are the 2 patterns in which crosslinking can occur?

A
  1. Intrastrand cross link
  2. Interstrand cross link
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29
Q

What is intrastrand crosslinking?

A

Atttachement of two regoins of the same DNA strand above or below

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30
Q

What is interstrand cross linking?

A

Attachment between two complimentary DNA strands (on the opposite side) or on a dompletely different DNA molecule

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31
Q

Define mutation:

A

An interaction of any ionizing radiation with a DNA molecule which causes either a loss/change in a nitrogenous base on the DNA chain

32
Q

What damage occurs from mutations?

A

-Incorrect genetic information transfered to one of the two daughter cells
-Cell death

33
Q

T/F

Radiation induced chromosome breaks occur in both somatic and reproductive cells

A

True

34
Q

What are the two types of chromosomal effects from radiation?

A
  1. Chromosomal fragments
  2. Chromosome anomalies
35
Q

What are the 2 types of chromosome anomalies?

A
  1. Chromosome aberrations
  2. Chromatid aberrations
36
Q

T/F

Chromosome breaks caused by radiation can be observed.

A

True

37
Q

At what phase does the chromosome duplicate itself?

A

During the S phase

38
Q

When do chromosome aberration damages occur?

A

Damage occurs before the S phase

39
Q

When do chromatid abberation damages occur? What part is affected?

A

-Damage occurs after the S phase
-Only 1 daughter cell is affected

40
Q

In what phase of cellular devisioon are cells most sensitive?

A

Mitosis

41
Q

At what phase in cellular division are cellls most radioresistant?

A

Cells are more radio-resistant during the late S phase

42
Q

Where do structural changes caused by radiation occur?

A

They occur within the nucleus

43
Q

What percentage of structural changes within the cell can be reversed?

A

95%

44
Q

What are the 4 consequences to the cell from structural changes in biologic tissue?

A
  1. Restitution
  2. Deletion
  3. Broken end rearangement/distorted chromosomes
  4. Broken end rearrangment without visible damage to chromatids
45
Q

What is deletion?

A

-Fragments of the chromosome lost during mitosis which creates an acentric fragment (no centromere)

46
Q

Can cell division take place without a centromere? What is the end result of deletion?

A

No; cell cannot replicate

47
Q

What is broken end rearrangment?

A

It is the process of rearranging broken ends of a chromosome

48
Q

What is inversion?

A

The same chromosome has 2 seperate breaks

49
Q

What is translocation?

A

Two different chromsomes with breaks

50
Q

If damage to the cells nucleus itself occurs, what are the ways that this is revealed?

7

A
  1. Instant death
  2. Reproductive death
  3. Apoptosis
  4. Mitotic, or genetric death
  5. Mitotic delay
  6. Inteference with function
  7. Chromosome breakage
51
Q

What causes instant death to the nucleus?

A

High doses of radiation

52
Q

What is reproductive death?

A

The cell survivies but it cant replicate

53
Q

What is apoptosis?

A

Natural way of getting rid of damaged cells

54
Q

What is mitotic/genetic death? What can cause this?

A

When the cell dies trying to divide, can be caused by small doses

55
Q

What is mitotic delay?

A

Division delay

56
Q

T/F

If radiation damages the germ cells, the damage may be passed on to future generations in the form of genetic mutations, mostly recessive

A

True

57
Q

Which type of damage requires more radiation for this to occur; somatic or genetic damage

A

Somatic damage requires more radiation

58
Q

What is the dose-response relationship?

A

The mathetmatical relationship betweeen raidation dose levels and the magnitude of the observed response.

59
Q

What are the applications of the dose-response relationships?

A
  1. Theraputic
  2. Radiation protection
60
Q

What is the deterministic effect?

A

The severity of damage with increased radiation dose

61
Q

What is the stochastic effect?

A

The incidence of damage occuring with increased radiation dose

62
Q

What are the two characteristics of every radaiton dose response?

A
  1. Linear or non linear
  2. Threshold or non-threshold
63
Q

What charecteristics of radiation dose response is diagnostic radiology more concerned with?

A

Linear non threshold radiation

64
Q

What is a linear response from radiation?

A

A response to the radiation and the severity of the biological effect increases directly with dose

65
Q

What is a threshold response from radiation?

A

A point at which a biological effect will occur, before that threshold amount, it will not occur

66
Q

What is a non-threshold response from radiation?

A

Radiation of any dose causing an effect

67
Q

What is A &B respresenting

A

A: A large response from a very small dose-non threshold
B: Low doses producing very little response, higher doses produce a greater response. Non threshold.

68
Q

What is C representing?

A

C: Doses below the threshold have no response, after threshold until the inflection point, there is an increase in the response

69
Q

What is the BERT value for the chest?

A

10 days (.08msV)

70
Q

What is the BERT value for the C spine?

A

2 weeks (.1msV)

71
Q

What is the BERT value for the T spine??

A

1 year (1.5 mSV)

72
Q

What is the BERT value for the L spine?

A

1.5 years (3mSv)

73
Q

What is the BERT value for the abdomen?

A

4 months (.7mSv)

74
Q

What is the BERT value for the pelvis?

A

4 months (.7msV)

75
Q

What are the 2 possible outcomes of two breaks within a single chromatid?

A
  1. Ring chromatid
  2. Ascentric fragments
76
Q

What are the 3 possible outcomes of breaks within 2 different chromatids?

A
  1. Could rejoin properly
  2. Broken end rearrangment
  3. Broken peices linking to oposite chromosomes
77
Q

What is the end result of broken end rearrangment?

A

Discentric and ascentric fragments causing elongated chromosomes not to spoint and results in reproductive death

Radiographic Protection and Radiobiology (11 decks)

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