Macromolecular Damage
What is an effect of in vitro irradiation of macromolecules?
Main-Chain Scission, Point Lesions, and Cross-linking
A visible chromosome aberration indicates what level of DNA damage?
Extensive DNA damage
Why do most radiation interactions in the body involve water?
The body is approximately 80% water
The direct effect of radiation occurs when radiation dose what?
Directly ionizes DNA
Cell survival is defined as the ability of a cell to do what?
Retain reproductive capacity
Main-Chain Scission refers to what type of damage?
Breakage of the macromolecule backbone
Which type of DNA damage involves a change or loss of a base and may not be repairable?
Radiolysis of water occurs when radiation does what?
With low-LET radiation, most DNA damage results from what type of effect?
Indirect effects
Cell-cloning experiments determine radiation lethality by measuring what?
Colony formation
Cross-linking causes biologic damage primarily by doing what?
Preventing normal molecular movement and function
A molecular lesion may result in what outcome?
Genetic mutation
Which products are formed during radiolysis of water?
H⁺, OH⁻, H·, and OH·
The oxygen effect increases radiation damage with low-LET radiation by doing what?
Enhancing indirect effects
The single-target, single-hit model best applies to which organisms?
Bacteria and viruses
A point lesion is best described as what?
A localized molecular change
Which cellular response may lead to late stochastic effects such as cancer?
Cellular transformation
Free radicals are biologically damaging because they are what?
Highly reactive
Why does oxygen have little additional effect with high-LET radiation?
Ionizations are already densely packed; the damage has already been done
The dose that kills 63% of cells is known as what?
D37
Radiation can interfere with macromolecular synthesis by disrupting production of what substances?
DNA, RNA, and proteins
Target theory states radiation must do what to cause damage?
Hit a critical target molecule
The indirect effect of radiation involves damage caused by what?
Free radicals formed from water
Which type of radiation effect is most influenced by oxygen presence?
Indirect effects
Which phase of the cell cycle is the most radiosensitive?
M-phase