5 - Radiation Carcinogenesis Flashcards
What are 2 forms of radiation?
electromagentic and particle
What is electromagnetic radiation?
waves and photons (ie: UV and x-rays)
What is particle radiation?
particles and sub-particles that makeup atoms that can fly out
Where do we get most of radiation exposure? Why?
radon = breaks down most radiation exposure and can go into our bodies via veggies and other food
What is radon? Where is it commonly found in?
an element, abundantly found in soil
What damage do x-rays have on DNA?
breaks DNA
Why are short wavelengths more dangerous than long wavelengths of light?
get more of them per second
What is the relationship of frequency with ionizing radiation?
as frequency and wavelength increase = increase in energy to push electrons out of orbitals
What is indirect action of ionizing radiation?
flying electron = free radical »_space;> grabs onto DNA electron = bond broken
What is direct action of ionizing radiation?
when the electron hits DNA directly
What are the proteins that sit on DNA?
histones | transcription factors | polymerases | repair enzymes
What disease does mutations in NER cause?
xeroderma pigmentosum
How cancerous are x-rays?
repair enzymes will effectively deal with them if minimally exposed
What are beta particles?
high-velocity electrons | by-product of radioactive decay of radioactive substances
What are alpha particles?
helium ions (+2 charge) | by-product of radioactive decay of radioactive substances
What are protons and neutrons?
sub-atomic particles making up the nuclei of atoms
What is radioactive decay?
when large atoms decay
When large atoms undergo radioactive decay, what happens to the neutrons in the nuclei?
convert straight to energy (how bomb works) OR will fly out and become alpha particle
What does LET stand for and what does it mean?
linear energy transfer | how much energy is transferred into environment
Which is worse and why: high LET or low LET?
low LET because it is losing a lot of energy as it travels = where is that energy going in our cells? | high LET = doesn’t leave much radiation behind
What is an example of low LET?
alpha particles and neutrons
What is an example of high LET?
gamma rays
What does “dose” mean?
how much dose is someone exposed to
What are the 2 common radiation units used?
GRAY and Sieverts
What is GRAY?
AMOUNT of radiation the tissue is absorbing
What is Sieverts (Sv)?
what is the biological IMPACT (scale) the amount of radiation tissue is absorbing
Which atoms are unstable?
those with large nuclei
Which atom has the largest nuclei but is stable?
uranium
Why is uranium important in terms of powerplants and bombs?
stable enough to handle and unstable enough to split easily (fission)
What is fission?
splitting of an atom
When firing a neutron at the Uranium atom results in splitting the atom, why is it the resulting pieces don’t add up to the whole?
some of the neutrons were converted to energy
What is a chain reaction in atom fission?
split of one atom = flying particles that will hit neighboring atoms = split those = cycle continues
How fast is the atom fission chain reaction?
logarithmic reaction = miliseconds
What are the buffers used to buffer neutrons?
uranium rods | water
What is radiation-induced cancer?
cancer due to radiation exposure (ie: bombs)
Why is getting hit with one big super hard dose of radiation better than a constant lower dose?
cells will get hit hard with the radiation = most likely will die
How long do adult stem cells stay with you?
many decades (more than 40)
What is instability in terms of radiation-induced cancer?
cells can get hit by radiation but genomic instability can be delayed due to not every type of mutation is equal
What dictates genomic instability?
rate of damage and rate of mutation
What are the 5 variables that dictate the risk for radiation-induced cancer?
Time (after exposure) | Age (at time of exposure) | Dose | Dose rate for low LET radiation | Quality of radiation (LET)
If you’re a cell that will be hit with radiation, when in the cell cycle would you rather get hit if not in G0? (G1, G2, S-phase, or M-phase) Why?
G2 | DNA repair mechanisms are at full speed ; only 1 sister chromatid will be involved
