the study of effects of ionizing radiations on living things
T/F: energy is directly deposited in a site in the cell.
Can visible changes in the cell from radiation be distinguished from other traumas?
biologic changes occur only after a period of time
Types of ionizing radiation
electromagnetic, particulate, manmade
Give examples of electromagnetic radiation
radiowaves, microwaves, infrared waves, UV light, gamma/x-ray radiation
tiny fast-moving particles that have both energy and mass
How is particulate radiation produced?
disintegration of an unstable atom; alpha or beta particles
Natural radiation comes from:
cosmic radiation, soil, water, plants, animals
What is the biggest source of manmade radiation dose?
medical and dental xrays
SI unit for Rad
What does Gray measure?
SI unit for Rem
What does Sievert measure?
The absorption of radiation in biological material may lead to _________ or ______________.
excitation or ionization
electron is raised to higher energy level
orbital electrons ejected
radiation interacts with a critical molecule in the cell, such as DNA or RNA.
Does high or low LET radiation undergo direct interactions?
radiation interacts elsewhere in the cell and eventually damages DNA.
Where does indirect action primarily take place?
Give examples of low LET radiation
x-rays or gamma
What do indirect interactions result in?
atom or molecule that contains an unpaired electron in the outer shell
Is an unpaired electron highly reactive?
ion free radical
both an ion (charged) and a free radical
What do ion free radicals decay to?
H2O+ combines with another H2O to form
hydroxyl free radical (OH*)
2 hydroxyl free radicals can combine to form
hydrogen peroxide; very toxic to cell
Single-target, single-hit target theory
theory that just one hit by radiation on a single sensitive target would lead to death of the cell
multitarget single-hit target theory
just one hit by radiation on each of n sensitive targets in the cell is required for death of the cell
LET (linear energy transfer)
amount of radiation deposited per unit path per unit of radiation
unit for LET
What does LET measure?
rate at which energy is transferred from ionizing radiation to tissue
increase mass= ___________ LET
increase charge = ____________LET
no mass/ no charge = _________LET
examples of high LET radiation
Examples of low LET radiation
x and gamma
Relative Biological Effectiveness (RBE)
ratio of absorbed doses from different types of radiation and their ability to produce the same biological effect
lowest to highest LET equipment
superficial, orthovoltage, Co-60, LINAC
RBE is based off a dose of
D250/Dr (dose of some "test" radiation)
allows comparison of doses from different "types" of radiation
100 REM = __________ Sv
dose x quality factor specific to type of radiation
quality factor of photons
quality factor of neutrons
quality factor of alpha particles
The basic unit of structure and function in living things
membrane, cytoplasm, organelles, nucleus
cell membrane function
Controls the movement of substances into and out of the cell; selectively permeable
site of all metabolic functions in the cell
building up, synthesis
protoplasm composed of:
water, organic compounds, inorganic compounds
mineral salts (sodium-outside cell, potassium- inside cell)
organic compounds found in cell
proteins, carbohydrates, nucleic acids, lipids
building blocks; 15% of cell content
examples of proteins
insulin, egg whites, gelatin, hemoglobin
structural proteins, enzymes, hormones, antibodies
What is the primary source of energy in the cell
1% of the cell, DNA and RNA
bases of RNA
adenine, guanine, cytosine, uracil
bases of DNA
Adenine, Thymine, Guanine, Cytosine
stores energy, insulates, protects and supports organs, and aids in digestion
most sensitive part of the cell
Adenine pairs with
Thymine or Uracil
Guanine pairs with
double stranded structure twisted upon itself to form a tightly coiled molecule that resembles a spiral staircase
complex structures in the nucleus that contain DNA and special proteins
alteration in the sequence of DNA
if a mutation is severe enough, what can be caused?
involved in protein synthesis; smooth or rough, houses the ribosomes; allows cell parts to communicate with each other
composed of protein and RNA; role in protein synthesis
power house of the cell; produce energy for cellular functions
garbage disposer of the cell; contains special enzymes to breakdown protein, DNA, and some carbohydrates
packaging area for products manufactured by the cell for export; carbohydrate synthesis
The synthesis phase of the cell cycle; the portion of interphase during which DNA is replicated.
What phase is the most radioresistant
period between division
process of somatic cells dividing; PMAT
chromatin becomes filamentous and visible
middle"; chromatids aligned in center of cell
apart"; migration of chromatids along spindle to opposite poles of the cell
reconstruction of the nuclear membrane and cytokinesis
oogonium of female and spermatogonium of male
cell division of germ cells
cell divides twice but chromosomes are duplicated only once
unspecialized cells that retain the ability to become a wide variety of specialized cells
one copy of DNA info
2 copies of DNA
The process by which a cell becomes specialized in order to perform a specific function, as in the case of a liver cell, a blood cell, or a neuron.
cell is more abnormal than normal looking cell
What is the standard international unit of absorbed dose?
Are x-rays directly or indirectly ionizing?
Low LET deposits little energy over a __________- distance
If low LET radiation more biologically damaging or more?
As LET increases, radiation produces _____ cell killing per Gray.
RBE depends on LET, and rises to a maximum at an LET of about 100 keV/um then falls for higher values of LET because of ______________
response of cells to radiation is strongly dependent on oxygen
OER is the ratio of
hypoxic dose/aerated dose
OER greater than 1
takes more dose to "kill" hypoxic cells
As LET increases, OER ______________-
the oxygen effect is more pronounced with what kind of radiation
x and gamma rays
OER for most mammalian cells
Are hypoxic or aerated cells easier to kill with radiation?
aerated; hypoxic cells generally need a higher dose to produce the same effect
What is the smallest unit of protoplasm capable of independent existence?
The most abundant constituent of protoplasm is _________, which is approximately ______________ water
What are the building blocks of a protein?
Name 3 components of a carbohydrate
carbon, hydrogen, oxygen
Carbohydrates are the primary source of __________ of the cell
What are the 2 nucleic acids in the cell?
DNA and RNA
3 functions of lipids in a cell
store energy, insulation, supports organs
Site of all metabolic functions in the cell?
What physically separates the nucleus from the cytoplasm?
What does DNA stand for?
How many nitrogenous bases are present in DNA?
What are the 2 categories of nitrogenous bases?
purines and pyrimidines
T/F: a purine will only pair with another purine
Define the term mutation
alteration in sequence of DNA
What type of ells divide by the process of mitosis
Division of the cytoplasm during cell division
Based on the site of interaction, the action of radiation of the cell can be classified as __________ or _____________
direct or indirect
T/F: direct action is most likely to occur after exposure to high LET radiation
What is the common name for H2O2 and what effect does it have on the cell?
hydrogen peroxide; toxic to the cell