what is anabolism
macromolecules being synthesized from smaller molecules
rad damage to macromolecules my result in what
cell death
what does molecular damage result in
the formation of structurally changed molecules that impar cell function.
damage to somatic cells disrupt body processes, and damage to germ cells may cause genetic mutuations
what is the most radiosensitive molecule? why?
DNA
because its most crucial, if its damaged cells cant divide and function properly
what are examples of molecules
water, oxygen
what are examples of macromolecules
lipids, protiens, carbs, RNA
what can happen if radiation causes damage to atoms
damage can carry onto molecules, tissues, and organs
how are the effects of ionizing rad classified
direct- rad interacts w macromolecules
indirect- damage occurs due to ionization of water molecules (xray causes it to make free radicals that do damage)
what is direct action
biologic damage occurs as a result of ionization of atoms on essential macromolecules like DNA, RNA, proteins, and enzymes
direct action is more likely to occur with low or high LET
high LET radiation
most radiation interactions in the body are with what type of molecule?
water molecules, body made up of 80% water molecules
what is radiolysis of water (direct action)
if an xray photon ionizes a water molecule the result may be a water molecule w a positive charge and a free elec. the elec may recombine w water OR could combine w a stable water mole resulting in a neg water ion.
the charged water ion is unstable and therefore can cause damage
what are the 2 most unstable ion pairs?
hydrogen ion H+ and hydroxyl radical OH
hydroxyl ion OH- and hydrogen radical H
explain what free radicals are
unstable molecule that contains a single unpaired elec in the outer shell. theyre highly interactive, have short life spans, and can damage cells a distance away from og site
two thirds of all rad damage is caused bu what? how does it do the damage?
hydroxyl free radical OH
causes damage by transferring their excess energy to other molecules
what is hydrogen peroxide
free radical OH and OH combine to make this highly toxic
what is hydroperoxyl radical
combo of oxygen and hydrogen free radical
what are the 2 most damaging free radicals
hydroperoxyl and hydrogen peroxide
what is indirect action
when the xray interacts w a water molecule which then is broken down into ions and free radicals which cause damage.
how can the damaging action of ionizing radiation be indirect
bc free radicals act on a molecule and damage it, the free radicle is a result of ionizing radiation but its not the radiation itself that caused the damage therefore its indirect
the byproducts of radiation cause the damage
