Biological Effects Flashcards by Brianne Bradford

4 phases of cell cycle:

M, G1, S, G2

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Cell phase(s) where there is a gap in cell growth

G1, G2

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Cell phase where there is DNA synthesis and the molecule is replicated to two molecules

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4 phases in M phase:

Prophase

Metaphase

Anaphase

Telophase

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Phase in M phase where DNA swells, takes structural form

Prophase

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Phase in M phase where Chromosomes appear and line up

Metaphase

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Phase in M phase where Chromosomes split

Anaphase

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Phase in M phase where Chromosomes become mass of DNA

Telosphase

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In ___ a second division without duplication of chromosomes occurs

Meiosis

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2 categories of human sensitivity to radiation:

organ sensitivity
cellular radiosensitivity

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Cellular radiosensitivity depends on 2 things:

rate of proliferation (how quickly the cells mature)
state of development of the cells (how differentiated or undifferentiated they are)

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Lymphocytes, spermatogonia, erythroblasts, intestinal crypt cells are ___ radiosensitive

highly

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Endothelial cells, osteoblasts, spermatids, fibroblasts have ___ radiosensitive

Intermediate

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Muscle cells, nerve cells have ___ radiosensitivity

low (radioresistant)

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Tissues with high radiosensitivity require __ - __ Gy to cause change in cells.

2-10

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Tissues with intermediate radiosensitivity require __ - __ Gy to cause change in cells.

10-50

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Tissues with low radiosensitivity require > __ Gy to cause change in cells.

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Lymphoid, bone marrow, and gonads are ___ radiosensitive

highly

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Skin, GI tract, cornea, growing bone, kidney, liver, and thyroid have ___ radiosensitivity

intermediate

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Muscle, brain, and spinal cord have ___ radiosensitivity

low

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Law of B andT says: Radiosensitivity of cells is ___ proportional to their reproductive activity and ___ proportional to their degree of differentiation (specialization)

directly, inversely

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Less specialized cells and cells with high metabolic rate are ___ sensitive to radiation

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LET

linear energy transfer

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rate at which energy is transferred from ionizing radiation to tissue

LET

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RBE

Radiobiological Effectiveness

As LET increases, RBE \_\_\_

increases

the higher the RBE, the ___ the radiosensitivity

higher

dose delivered over a period of time

Protraction

dose delivered in discrete fractions

Fractionation

OER

Oxygen Enhancement Ratio

oxygenated (oxygen present)

Aerobic

OER (oxygen enhancement ratio) has more effect with ___ LET (linear energy transfer).

low

Age sensitivity to radiation: 3 most sensitive age groups

1. Unborn 2. Very young (kids) 3. Elderly

Recovery is ___ and \_\_\_\_

repair, repopulation

Interphase death means cells die before \_\_\_

replicating

Chemo given 1 hour before RT is an example of a \_\_\_, which ___ the effect of RT.

Radiosensitizer, enhances

\_\_\_ mitigate the effect of RT, but doses are too toxic to use in RT.

radioprotector

Molecular Radiobiology: when radiation makes a cut in the chain

Main-Chain Scission

Molecular Radiobiology: when radiation causes two parts to join or link together at a point where they shouldn't

Cross-Linking

Molecular Radiobiology: when radiation damages information at only the point that it hits

Point Lesion

2 types of main-chain scission:

1. one side rail severed 2. both side rails severed

4 radiation effects on DNA:

1. cell death 2. abnormal replication 3. genetic abnormalities 4. repair

Radiolysis of water (in Radiobilogy): Water ___ or __ an electron. Ion pairs recombine and form \_\_\_.

gains, loses, free radicals

Uncharged molecule with unpaired ____ can combine to create \_\_\_, which is __ to cells.

valence electron, Hydrogen Peroxide (H2O2), toxic

Damage due directly to radiation (DNA damage), where effect is seen at cellular level

Direct effect

Ionizing event creates molecule which damages another cell (Free radicals) and the primary effect is seen at the whole body level.

Indirect effect

\_\_\_ effect usually occurs shortly after exposure and is associated with higher doses of radiation

deterministic

\_\_\_ effect usually occurs very long after exposure and is associated with lower doses of radiation

stochastic

Dose response relationships have been determined using 3 ways:

1. experiments 2. accidental exposures 3. natural exposures (background radiation in the environment i.e. Denver)

Horemesis dose response (theory/graph) says what about low doses of radiation?

it is good

favorable biological response to low exposure to that which would be toxic or harmful at large exposures

Hormesis

\_\_\_\_ theory is used. It is considered conservative. It is not validated at ___ doses, meaning we don't actually have any data.

linear non-threshold, low

In atomic bomb survivors, no observed increase in cancer for exposures less than ___ mSv

150

French Academy of Sciences (2005) says there is no evidence of validity of NLT model to estimate carcinogenic risks at doses less than ___ mSv

100

Spontaneous Mutations: natural background mutation rate ___ typical radiation background mutation rate by 10^6

exceeds

No biological basis for LN-T. In fact, biology suggests a ___ to low doses of radiation

benefit

- Radiation effects are ___ at large exposures in short time frame - Small exposures, longer time effects are \_\_\_

known, less well known

Prophase

Metaphase

Anaphase

Telophase

Identify where both mitosis and meiosis are occuring.

Identify each type of DNA damage:

A: Main-Chain Scission B: Cross-Linking C: Point Lesion

Identify each type of DNA damage:

A: Main-chain scission - one side rail severed B: Main-chain scission - both siderails severed

Identify each type of DNA damage:

C: Main-chain scission followed by cross-linking D: Rung breakage – separation of bases

Identify the following chromosomes as normal or damaged, if damage what type of damage?

A: normal B: terminal deletion C: dicentric formation D: ring formation

4 types of cells that are highly sensitive ot radiation:

Lymphocytes spermatogonia erythroblasts intestinal crypt

4 types of cells that have intermediate radiosensitivity

Endothelial cells osteoblasts spermatids fibroblasts

\_\_\_ cells and ___ cells have low radiosensitivity

Muscle, nerve

3 organs with high radiosensitivity:

Lymphoid bone marrow gonads

7 organs with intermediate radiosensitivity:

Skin GI tract cornea growing bone kidney liver thyroid

3 organs that have low radiosensitivity:

Muscle brain spinal cord

Water gains or loses an electron. Ion pairs recombine and form free radical.

Radiolysis of water (in Radiobilogy):