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RT 244 ch 31,32
Radio-biology chapters 31, 32, inverse square
Question | Answer |
---|---|
Regarding the radiosensitivity of macromolecules, the most radiosensitive is? | DNA |
Most cellular radiation damage resulting in a late total body effect and thought to be the site of radiation induced malignancies, is known as? | Point lesions |
The initial ionizing event produces two ions, they are? | HOH+ and e- |
The most common interaction of radiation and DNA is a result of what type of effect? | Indirect effect |
What does in vivo mean? | within the living cell |
Radiation effects occuring in vivo at the total body level occur mainly as a result of direct or indirect effect? | Indirect |
What does in vitro mean? | outside the body, outside the cell |
What is critical to the survival of the cell and its replication? | Macromolecular sythesis of proteins, DNA, and RNA |
The breakage of the thread or backbone is a long-chain macromolecule when irradiated in vitro is called? | main-chain scission |
What are the three principle observable effects resulting from irradiation of DNA in vivo? | cell death, malignant diseases, and genetic damage |
Regarding viscosity, after cross-linking occurs, describe the irradiated in vitro solution: | there is a increase in viscosity |
What is a reactive atom or molecule having an unpaired electron in its outer shell? | free radical |
When HOH+ dissociates into small molecules, what does it separate into? | H+ and OH* |
When HOH- dissociates into small molecules, what does it seperate into? | OH- and H* |
What are the free radicals produced during radiolysis of water? | H* and OH* |
2 hydroperoxyl free radicals join to form what? | H202 (hydrogen peroxide) |
An initial ionizing event occurs on a distant, non-critical molecule that transfers the energy of ionization to a target molecule, is this direct or indirect? | Indirect |
This radiation effect on a macromolecule has a sticky substance on the end that attaches to neighbors or to another segment of the same molecule, what effect is this? | cross-linking |
In what phase is the cell most sensitive? | M phase |
In what phase is the cell least sensitive? | S phase |
Regarding viscosity, when main-chain scission occurs in the solution,what happens to the irradiated in vitro solution? | viscosity decreases |
What is the irradiation of water that represents the principal interaction in the body? | radiolysis |
How long is the life of a free radical? | less than 1 ms |
What are the damaging products of radiolysis of water? | hydrogen peroxide and hydroperoxyl |
In terms of oxygen, radiation effects on human tissue are more effective if the cells are irradiated under what conditions? | aerobic |
The principal radiation interaction within the human body is with what? | water |
Radiation damage to DNA can result in? | cell death, malignant diseases, genetic changes |
A type of DNA damage that may not be reversible is what? | base change or loss |
After a low radiation dose, most cellular radiation damage that results in a late total-body effect occurs because of which of the following? | Point lesions |
The probability of human cell death can be computed by using what? | Poisson distribution |
The difference in generation time among different types of cells is due mainly to the length of which phase? | G1 phase |
What law states that the intensity of radiation at a location is inversely proportional to the square of its distance from the source of radiation? | Inverse square law |
What is the thickness of a material? | viscosity |
What model applies to biologic targets, such as enzymes, viruses, and simple cells such as bacteria? | Single Target, Single Hit |
What model applies to more complicated biologic systems such as human cells? | Multitarget, Single hit |
What is the dose that results in 37% cell survival? | D37 |
LET stands for? | Linear energy transfer |
RBE stands for? | Relative biologic effect |
OER stands for? | Oxygen enhancement ratio |
What is radiation induced structural change in chromosomes? | Cytogenetic damage |
What is the breakup of large molecules into smaller molecules? | Catabolism |
What is the construction of large molecules from smaller molecules? | Anabolism |
A cell's DNA has been irradiated. What are you most concerned about? | genetic damage or mutation |
What phase of DNA synthesis is said to resemble a zipper opening? | S phase |
What is a liquid that contains dissolved substances? | solution |
What are the 3 types of radiation-damage to human chromosomes? | Terminal deletion, dicentric formation, and ring formation |
What 4 types of damage that occurs to DNA is reversible? | one side rail severed, both side rails severed, cross-linking, and rung breakage |