MOLECULAR & CELLULAR RADIOBIOLOGY, EARLY EFFECTS OF RADIATION

Question 1

What are point lesions in molecular radiobiology?

Answer 1

Cellular radiation damage that leads to late radiation effects.

Question 2

What are the two processes metabolism consists of?

Answer 2

Catabolism and anabolism

Question 3

Which molecule is considered the most radiosensitive?

Answer 3

DNA.

Question 4

What is the principal radiation interaction in the human body?

Answer 4

Radiation interaction with water.

Question 5

Irradiation outside of the cell or body.

Answer 5

in vitro irradiation

Question 6

Irradiation within the cell or body.

Answer 6

in vivo irradiation

Question 7

The breakage of the backbone of long-chain macromolecules.

Answer 7

main-chain scission

Question 8

What does main-chain scission result in?

Answer 8

Reduction of a long molecule into many smaller ones and decreased viscosity.

Question 9

What effect does cross-linking have on macromolecules?

Answer 9

Increases the viscosity of the solution.

Question 10

A change that impairs or loses function at a single chemical bond.

Answer 10

point lesion

Question 11

The reduction of nutrient molecules for energy.

Answer 11

catabolism

Question 12

The production of large molecules for form and function.

Answer 12

anabolism

Question 13

What is translation in protein synthesis?

Answer 13

Forming a protein molecule from messenger RNA.

Question 14

What is transcription?

Answer 14

Constructing messenger RNA from DNA.

Question 15

Which is more abundant, proteins or nucleic acids?

Answer 15

Proteins.

Question 16

Which is less radiosensitive, proteins or nucleic acids?

Answer 16

Proteins.

Question 17

Deoxyribose, phosphate, and base molecules accumulate, forming the double-helix DNA.

Answer 17

G1 portion of interphase

Question 18

DNA unzips and forms two daughter DNA molecules.

Answer 18

S portion of interphase

Question 19

What do chromosomes control in a cell?

Answer 19

The growth and development of the cell.

Question 20

What are the two types of chromosome aberrations?

Answer 20

Terminal deletion and dicentric formation.

Question 21

What is an ion pair created by radiolysis of water?

Answer 21

HOH+ and e-.

Question 22

Uncharged molecules with an unpaired electron; short-lived.

Answer 22

free radicals

Question 23

What toxic agent is formed by radiolysis of water?

Answer 23

Hydrogen peroxide (H2O2).

Question 24

What is the principal damaging product of radiolysis of water?

Answer 24

Hydroperoxyl radical (HO2*).

Question 25

When the initial ionizing event occurs on the target molecule.

Answer 25

direct effect

Question 26

When the ionizing event occurs on a noncritical molecule and energy is transferred.

Answer 26

indirect effect

Question 27

Theory that a cell dies if its target molecule is inactivated by radiation.

Answer 27

target theory

Question 28

What is a radiation "hit"?

Answer 28

An ionization that inactivates the target molecule.

Question 29

How does low-LET radiation interact in the absence of oxygen?

Answer 29

Low probability of hitting target molecules.

Question 30

How does oxygen affect low-LET radiation?

Answer 30

Increases probability of a hit by forming free radicals.

Question 31

What model applies to enzymes, viruses, and bacteria for cell survival?

Answer 31

Single-Target, Single-Hit Model.

Question 32

Define D37.

Answer 32

Dose required to kill 63% of cells (37% survive); measures cell radiosensitivity.

Question 33

Which phase is most variable in cell cycle time?

Answer 33

G1 phase.

Question 34

Which cell survival model applies to human cells?

Answer 34

Multi-Target, Single-Hit Model.

Question 35

What does a high D0 value indicate?

Answer 35

Radioresistant cells.

Question 36

What does DQ represent in the multitarget model?

Answer 36

The threshold dose and cell recovery capacity.

Question 37

Damage that must accumulate before cell death occurs.

Answer 37

sublethal damage

Question 38

Describes the cell's ability to recover from sublethal damage.

Answer 38

split-dose irradiation

Question 39

What is the average cell-cycle time for human cells?

Answer 39

Approximately 24 hours.

Question 40

Which phase in the cell cycle is the most sensitive to radiation?

Answer 40

Mitosis.

Question 41

How does oxygen influence radiation effects?

Answer 41

Enhances the effect of low-LET radiation.

Question 42

What type of radiation response is deterministic?

Answer 42

A response that varies in severity with radiation dose and has a threshold.

Question 43

What is the prodromal period in acute radiation syndrome?

Answer 43

Initial symptoms like nausea and vomiting after exposure.

Question 44

What characterizes the hematologic syndrome?

Answer 44

Reduction in white, red cells, and platelets; dose range 200-1000 rad.

Question 45

What dose range causes GI syndrome?

Answer 45

1000-5000 rad.

Question 46

What symptoms are associated with CNS syndrome?

Answer 46

Ataxia, seizures, and loss of coordination.

Question 47

What does LD50/60 measure?

Answer 47

Dose causing 50% of subjects to die within 60 days.

Question 48

What tissues are most affected by local radiation exposure?

Answer 48

Skin, gonads, and bone marrow.

Question 49

Shrinkage of an organ or tissue due to cell death.

Answer 49

atrophy

Question 50

What are the three layers of skin?

Answer 50

Epidermis, dermis, and subcutaneous layer.

Question 51

What cells in the skin are most radiosensitive?

Answer 51

Basal cells in the epidermis.

Question 52

Reddening of the skin similar to sunburn.

Answer 52

erythema

Question 53

Ulceration and peeling of the skin.

Answer 53

desquamation

Question 54

What dose causes temporary epilation?

Answer 54

300 rad.

Question 55

What is the SED50?

Answer 55

Dose causing skin erythema in 50% of people, about 500 rad.

Question 56

What dose causes temporary sterility in men?

Answer 56

200 rad.

Question 57

What dose causes permanent sterility in women?

Answer 57

500 rad.

Question 58

Includes bone marrow, circulating blood, and lymphoid tissue.

Answer 58

hemopoietic system

Question 59

What cells are involved in the immune response?

Answer 59

Lymphocytes.

Question 60

rapid decrease in granulocytes.

Answer 60

granulocytopenia

Question 61

Platelets involved in blood clotting.

Answer 61

thrombocytes

Question 62

What cells are least sensitive to radiation?

Answer 62

Erythrocytes (red blood cells).

Question 63

A chromosome map used in cytogenetic analysis.

Answer 63

karyotype

Question 64

What are single-hit chromosome aberrations?

Answer 64

Chromosomal damage observed during the M phase.

Question 65

A chromosome formed by joining segments from two hits.

Answer 65

dicentric chromosome

Question 66

The study of cell genetics, particularly chromosomes.

Answer 66

cytogenetics

Question 67

How are radiation-induced point mutations detected?

Answer 67

They are undetectable even with karyotype analysis.

Question 68

What is the dose-response relationship for single-hit aberrations?

Answer 68

Linear, nonthreshold.

Question 69

What are iso-chromatid fragments?

Answer 69

chromatid fragments without centromeres.

Question 70

What causes stickiness in chromosomes?

Answer 70

Mechanism failure for chromatid joining.

Question 71

What radiation dose affects lymphocytes?

Answer 71

As little as 25 rad can cause hematologic depression.

Question 72

A rapid rise in granulocytes, typically after exposure.

Answer 72

granulocytosis

Question 73

What is the principal effect of radiation on blood cells?

Answer 73

Depression of blood cell numbers.

Question 74

Red blood cells that transport oxygen

Answer 74

erythrocytes

Question 75

How long do red blood cells live in the peripheral blood?

Answer 75

Approximately 4 months.

Question 76

What is the most radiosensitive phase of male gametogenesis?

Answer 76

Spermatogonial stem cells.

Question 77

What causes radiation-induced atrophy of the ovaries?

Answer 77

Irradiation, especially early in life.

Question 78

The development process of germ cells in testes and ovaries.

Answer 78

gametogenesis

Question 79

What type of radiation is associated with orthovoltage x-rays?

Answer 79

200-300 kVp x-rays.

Question 80

Ulceration of the skin that represents clinical intolerance.

Answer 80

moist desquamation

Question 81

What are the symptoms of prodromal radiation sickness?

Answer 81

Nausea, vomiting, and diarrhea.

Question 82

What is a ring chromosome aberration?

Answer 82

Chromosomal damage from two hits on the same chromosome.

Question 83

How long is the latent period in radiation sickness?

Answer 83

It varies based on dose, usually no symptoms present.

Question 84

What is the GI syndrome dose range?

Answer 84

1000-5000 rad.

Question 85

Define hemopoietic cell survival.

Answer 85

Decrease in circulating blood cells due to radiation.

Question 86

What is the approximate chromosome aberration frequency?

Answer 86

Two single-hit aberrations per rad per 1000 cells.

Question 87

What is the CNS syndrome's ultimate cause?

Answer 87

Elevated fluid content in the brain.

Question 88

What is the effect of high-LET radiation on cell survival models?

Answer 88

Follows single-target, single-hit model.

Question 89

What is a reciprocal translocation?

Answer 89

A rearrangement of genes without genetic loss.

Question 90

What cells recover from radiation damage in 6 months to 1 year?

Answer 90

Erythrocytes.

Question 91

What is a lethal dose response?

Answer 91

Nonlinear, threshold for acute radiation lethality.

Question 92

What does radiation-induced thrombocytopenia cause?

Answer 92

Depletion of platelets, leading to hemorrhage risk.

Question 93

What is the primary function of lymphocytes?

Answer 93

Immune response regulation.

Question 94

What radiation dose can suppress menstruation in women?

Answer 94

As little as 10 rad.

Question 95

What cell system is similar to hemopoietic system?

Answer 95

Gametogenesis, both involve cell renewal.

Question 96

What is a bone marrow's function in adults?

Answer 96

Produces most circulating blood cells.

Question 97

What type of radiation effect follows a threshold relationship?

Answer 97

Deterministic effects like local tissue damage.

Question 98

What are the three main effects of radiolysis?

Answer 98

Ion pair formation, free radicals, and hydrogen peroxide.

Question 99

What is the dose threshold for chromosome aberrations?

Answer 99

Approximately 5 rad.

Question 100

What is the lifespan of granulocytes in bone marrow?

Answer 100

8-10 days.

Question 101

What dose causes erythema in radiation patients?

Answer 101

Approximately 200 rad.

Question 102

What cells show a nonthreshold response to chromosome aberrations?

Answer 102

Human lymphocytes.

Question 103

What are the symptoms of CNS radiation syndrome?

Answer 103

Disorientation, seizures, loss of muscle coordination.

Question 104

What does linear energy transfer determine?

Answer 104

The magnitude of biological damage.

Question 105

What does RBE compare?

Answer 105

Effectiveness of test radiation vs. x-radiation.