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Molecular and Cellular Biology
N/A
34
Physics
Professional
04/18/2013

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Term
breakage of the backbone of the long chain macromolecule
viscosity of the solution is also changed
Definition
main-chain scission
Term
when side structures attach to neighboring macromolecules or to another segment of the same molecule
this will increase the viscosity of a solution
Definition
cross-linking
Term
disruption of single chemical bonds
considered to be the cellular radiation damage that results in late radiation effects from low doses
Definition
point lesions
Term
if a macromolecule has a point lesion, it will ____, decreasing the viscosity
Definition
break down into smaller molecules
Term
synthesis of __ and __ are critical to the survival of the cell and its reproduction
Definition
proteins and nucleic acids
Term
proteins are ___ radiosensitive than nucleic acids
Definition
less
Term
the most radiosensitive molecule
Definition
DNA
Term
this DNA damage may not be reversible
is a molecular lesion of the DNA
Definition
change in/ loss of a base
Term
a chagne in or loss of a base is a molecular lesion called ___
Definition
point mutations
Term
three observable effects
Definition
cell death
malignant disease
genetic damage
Term
malignant disease and genetic damage are ____ relationships
Definition
types of linear, nonthreshold dose-response
Term
when irradiated water dissociates into other molecule products
Definition
radiolysis
Term
___ represents the principal radiation interaction in the body
Definition
irradiation of water
Term
an unpaired electron
Definition
free radical
Term
has a charge
Definition
ion
Term
final dissociation will form:
Definition
an ion pair: H+ and OH-
and two free radicals: H* and OH*
Term
the ions may recombine with other free radicals to produce
Definition
H2O2 (hydrogen peroxide)
Term
a photon that ionizes a critical molecule within the cell, thereby damaging the cell
Definition
direct effect
Term
considered to be direct effets if they occur with DNA molecules
Definition
ionizing events
Term
a secondary or scatter photon (also possibly from the primary beam) damages a critical molecule within the cell
most radiation interactions and most radiation damage is caused by this
Definition
indirect effects
Term
an indirect effect from ionizing radiation occurs on a ___
Definition
water molecule
Term
a hit to a target cell can occur from:
Definition
a direct OR indirect effect
Term
photon-> water-> dissociation-> DNA molecule (target)
Definition
a hit to target cell by indirect effect
Term
explains why some cells die when exposed to radiation and others survive
Definition
target theory of radiation
Term
some molecules occur in very limited number within a cell and are called:
Definition
critical or target molecules
Term
if a target molecule is damaged, and there are no others to take its place, the cell may die
Definition
the target theory of radiation
Term
striking a target molecule is a ____
Definition
random event
Term
the way to determine the lethal effects of radiation by observing cell survival
Definition
cell survival kinetics
Term
two models of cell survival
Definition
single target, single hit
multitarget, single hit
Term
biologic targets such as enzymes, viruses and simple bacteria
Definition
single target, single hit
Term
a single target, single hit indicates a ____ that must be inactivated for the cell to die
Definition
single sensitive site (target)
Term
applies to much more complicated biologic systems such as human cells
indicates more than one sensitive site, therefore a higher survival rate
Definition
multi-target, single hit
Term
multitarget, single hit
Definition
DNA has 46 targets (23 pairs of chromosomes)
Term
cells are most radiosensitive during ___
Definition
mitosis
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