(1) Radiation Physics Biological/Cellular Unit 2
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Radiation Biology/ Cellular Effects- Part I
107 Terms
What is the most abundant molecule in the body?
Water
Water makes up __% of the molecular body
80
Proteins make up ___% of the molecular body
15
Lipids make up __% of the molecular body
2
Carbohydrates make up __% of the molecular body
1
Nucleic acids make up __% of the molecular body
1
DNA makes up __% of the molecular body?
1 (same as nucleic acids)
Other/inorganic salts make up __% of the molecular body
1
What are the most abundant atoms in the body?
Hydrogen and oxygen
How much hydrogen is the body atomically composed of?
60%
How much oxygen is the body atomically composed of?
25.7%
How much carbon is the body atomically composed of?
10.7%
How much nitrogen is the body atomically composed of?
2.4%
How much caclium is the body atomically composed of?
0.2%
How much phosphorus is the body atomically composed of?
0.1%
How much sulfur is the body atomically composed of?
0.1%
How much trace elements is the body atomically composed of?
0.8%
What are the 3 organic compounds in the cells?
Carbohydrates, lipids, proteins
What type of organic compound provides energy for cellular processes?
Carbohydrate
What type of organic compound provides energy storage and is important for the structural component of the cell membrane?
Lipids
What type of organic compound performs many structural and functional roles in the cell?
Proteins
T/F - Radiation effects to the nucleus can be lethal and kill the cell?
True
T/F - Radiation effects to the membrane are not lethal?
True
What are the two major parts of a cell?
Nucleus and cytoplasm
What part of the cell contains DNA/chromosomes?
Nucleus
What is the control center of the cell?
nucleus
What is the cytoplasm primarily composed of?
Water
What two cell structures are particularly important for radiation effects
Nucleus and cell membrane
DNA and RNA are what type of molecules?
Nucleic acids
What contains all the hereditary information of the cell?
Nucleic acid
What contains the blueprints for protein synthesis?
Nucleic acids
What has a control mechanism to regulate the cell’s metabolism and reproduction?
Nucleic acids
What are the three major differences of DNA/RNA?
Sugar - DNA has deoxyribose, RNA has ribose
DNA base thymine, RNA base uracil
DNA double helix, RNA single spiral
What bases of DNA pair up together?
A = Adenine and T = Thymine
G = Guanine and C = Cytosine
What structure has a double helix twisted ladder?
DNA
How long is DNA?
1.8m
What type of cells in the body undergo cell division by mitosis?
Somatic cells
Most cells in the body are what type?
Somatic cells
What type of cells are non-reproductive cells?
Somatic cells
What cells in the body are termed genetic cells?
Reproductive cells
What cells in the body undergo cell division by meiosis?
Reproductive cells
What stage in the cell cylce cannot be observed with a conventional light microscope?
interphase
What is the longest phase of the cell cycle?
Interphase
What are the three phases of interphase?
G₁, S, and G₂
During what phase of interphase does the cell grow, doubles its organelles, and prepares for DNA synthesis?
G₁ phase
During what phase of interphase is DNA replicated
S phase
During what phase of interphase do chromosomes go from one chromatid to two identical chromatids?
S phase
What phase of interphase does the cell synthesizes proteins needed for cell division?
G₂ phase
What occurs after G₂?
Mitosis
What are the four stages of cell division (mitosis)?
Prophase, metaphase, anaphase, and telophase
What type of cells undergo mitosis?
Somatic cells
What is the purpose of mitosis?
Growth, repair, and replacement/preservation of body cells
How many divisions occur in mitosis?
1
How many daughter cells are produced by mitosis?
2 diploid (2n) cells
How many chromosomes are in a human somatic daughter cell after mitosis?
46
What type of cells undergo meiosis?
Germline/genetic cells
What is the purpose of meiosis?
Formation of gametes for reproduction
How many divisions occur in meiosis?
2
What are the two divisions of meiosis?
Replication division and reduction division
How many daughter cells are produced by meiosis?
4 haploid (1n) cells
How many chromosomes are in a human gamete after meiosis?
23
What happens to the chromosome number during meiosis?
It is reduced by half, from 2n to 1n
Is DNA replicated between the two meiotic divisions?
No
What phase is skipped between the two divisions of meiosis?
S phase
What is the major difference between mitosis and meiosis?
Mitosis produces 2 diploid cells, while meiosis produces 4 haploid cells
Which process maintains the chromosome number?
Mitosis
Which process reduces the chromosome number by half?
Meiosis
What radiation effect directly attacks the DNA?
Direct effect
What radiation effect causes electrons to be released that can disrupt chemical bonds?
Direct effect
What radiation effect interacts with water first?
Indirect effect
What radiation effect produces free radicals from the interaction with water that can attack molecules like DNA?
Indirect effect
What type of radiation effect is more important with diagnostic x-rays?
Indirect effect because the body contains so much water
What are the steps in radiolysis of water?
Radiation ionizes water
Ions and free radicals form
H⁺ = hydrogen ion
OH⁻ = hydroxyl ion
H• = hydrogen radical
OH• = hydroxyl radical (very damaging)
Additional reactions occur
H• + O₂ → HO₂• (hydroperoxyl radical)
Hydroperoxyl radicals can produce _____ which is very toxic to the cell → Hydrogen peroxide
Hydroperoxyl radicals can produce _____ which is very toxic to the cell
Hydrogen peroxide
What is an uncharged molecule that contains a single electron in the outer shell?
Free radical
What are some examples of free radicals?
H• = hydrogen radical
OH• = hydroxyl radical (very damaging)
Why are free radicals damaging to cells?
They are highly reactive (contain excess energy) and can attack critical molecules such as DNA/RNA, altering the cellular function by disrupting bonds & producing point lesions at some distance from the initial ionizing event
Free radicals primarily form from?
Radiolysis of water (radiation ionizes water)
What is the most important free radical for radiation damage?
OH• = hydroxyl radical
What is a poisonous toxic agent to cells?
Hydrogen peroxide
When ionizing radiation interacts with the body, electrons are ripped from what kind of molecules?
water
What has the ability to affect the chemical state of a material and cause changes which are biologically important?
ionizing radiation
What are the four effects of ionizing radiation on DNA?
Radiation passes through with no damage
Radiation damages cell but it repairs the damage
Radiation damages the cell and it cannot repair the damage → Reproduces itself in damaged form (biological response)
Radiation causes so much damage that cell dies
What type of radiation dose mainly damages cells?
Low dose
What type of radiation dose mainly kills cells?
High dose
T/F - Stochastic effects have a threshold dose of 100mGy?
False, there is no threshold dose
Carcinogenesis (cancer) are examples of what radiation effect?
Low dose - Stochastic effects
Genetic effects are examples of what radiation effect?
Low dose - Stochastic effects
What type of dose/effect is random?
Stochastic (low dose)
T/F - There is no threshold dose for stochastic effects
True
What type of effect is assumed to be a linear function of dose without threshold?
Stochastic effects
The probability for stochastic effects ____ as dose increases
Increases (randomly)
T/F - In stochastic effects as dose goes down, it is much less likely that the effects will be seen
True
Most diagnostic exams are what kind of dose/effect?
Low dose (stochastic)
Cataracts are examples of what radiation effect?
Deterministic (high dose)
Reddening of skin is an example of what radiation effect?
Deterministic (high dose)
Burns are examples of what radiation effect?
Deterministic (high dose)
Hair loss is an example of what radiation effect?
Deterministic (high dose)
Blood changes are examples of what radiation effect?
Deterministic (high dose)
temp/permanent sterility is an example of what radiation effect?
Deterministic (high dose)