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Physics 3 - Test 1 Review

Terms in this set (64)

What are the two major structures of the cell?
nucleus and cytoplasm
The principal molecular component of the nucleus is
DNA
The nucleus contains:
DNA
RNA
Protein
Water
Most of the RNA is contained in a rounded structure called?
nucleolus
The ______ is attached to the nuclear membrane that at some locations is connected to the endoplasmic reticulum
nucleolus
The _____ makes up the bulk of then cell and contains great quantities of all molecular components except DNA.
cytoplasm
A number of intracellular structures are found in the ______
cytoplasm
The _____ is a channel or a series of channels that allows the nucleus to communicate with the cytoplasm
endoplasmic reticulum
The large bean-shaped structures are called ______
mitochondria
Macromolecules are digested in the ______ to produced energy for the cell
mitochondria
The small, dot-like structures are ______
ribosomes
______ are the site of protein synthesis and therefore are essential to normal cellular function.
ribosomes
_____ are scattered throughout cytoplasm or the endoplasmic reticulum
ribosomes
The small pea-like sacs are
lysosomes
The ____ contain enzymes capable of digesting cellular fragments and sometimes the cell itself.
lysosomes
_____ help to control intracellular contaminants
lysosomes
_____ provide structure and form for the cell and its components
cellular membranes
Define cell theory
All living things are composed of cells and come from preexisting cells
What are the 5 principle molecules found in the body/
...
______ are very large molecules that sometimes consist of hundreds of thousands of atoms
macromolecules
____ is the most abundant molecule in the body
water
The body is _____% water
80
The body is _____% protein
15
The body is _____% lipids
2
The body is _____% carbohydrates
1%
The body is _____% nucleic acid
1
Describe mitosis
the division phase which is characterized by four subphases: prophase, metaphase, anaphase, telophase
What type of division occurs in meiosis?
reduction
Radiation induced chromosome damage is analyzed during
metaphase
Describe meiosis
A form of cell division, which results in the production of four genetically different gametes.
State the law of Bergonie and Tribondeau
Radiosensitivity is increased with:
1. Stem/undifferentiated/precursor cells
2. Young, immature tissues or organs
3. Highly mitotic cells
4. Tissues with high metabolic rate
Skin radio-sensitivity is
high
The most radioresistant tissue is
nerve cells
What are the physical factors that affect radiation response
- type of radiation
- the way the dose is delivered (all at once or fractionated)
- LET
- RBE
What are the biologic factors that affect radiation response?
- presence of oxygen
- chemical agents (radio sensitizers or radio protective agents)
- hormesis
Define hormesis
a little radiation is good for you
Define RBE
is a number of the amount of damage .... relationship between LET and biological damage.
Define LET
a measure of the rate at which energy is transferred from ionizing radiation to soft tissue
As LET increases, RBE ____
increases
Define: Linear Non-threshold curve
Straight Line
Directly out of the corner

No safe dose, as the dose increases the effect will increase
Define: Linear Threshold Curve
Straight line
not directly out of the corner

Safe dose - Until a certain specific point
Define: Non-Linear, Non-Threshold Curve
Not a straight line
Starts directly out of the corner

No safe dose
Define: Non-linear Threshold curve
Not straight curve
Does not come directly out of the corner

Safe dose
Define radiation dose response relationships?
a mathematical relationship between various radiation dose levels and magnitude of the observed response
When macromolecules are irradiated in solution in vitro, three major effects occur:
1. main-chain scission
2. cross-linking
3. point lesions
Define main chain scission
breakage of the backbone of long-chain macromolecule. It results in long single molecule into smaller molecules
Define point lesions
cellular radiation damage causing malfunction of a cell.
Define cross linking
small spur-like structures attaching to a neighboring macromolecule
What effects does radiation have on DNA?
-One side rail severed
-both side rails severed
-cross-linking
-rung breakage (separation of bases)
-the change or loss of a base
visible chromosome aberrations occur when
radiation damage to DNA is severe enough
Several distinct types of chromosome aberrations:
Terminal deletion, dicentric formation, and ring formation
DNA damage without detectable aberration
May lead to cell death or abnormal metabolic activity
Free radicals are
highly reactive and short lived
H2O2 is...
stable and will last longer than free radicals
Macromolecular damage remote to the point of irradiation may occur due to
the stability hydrogen peroxide
In direct effect, there is direct ionization of the
DNA macromolecules
The principal bio effect of irradiation is due to the
indirect effect
In indirect effect, there is breakdown of
the water molecule
Why is indirect effect the chief cause of bio effect of irradiation?
because the body is mostly water
Discuss the difference in radiation responses in vivo compared with in vitro.
When biologic material is irradiated in vivo, the harmful effect is the damage to the DNA. The direct effect is demonstrated in vitro. Because the human body is 80% water, it is safe to assume that most radiation damage in vivo is from indirect effects.
Describe the principles of Target theory:
there are 2 types of model: single target, single hit; multi-target single hit

Single target structures are simple structures such as viruses/bacteria (only need one hit to kill the cell)

Multi-target structures are human cells with repair processes (need multiple hits in order to inactivate it)
What is the most radio resistant time?
late S phase
When is radio resistance low?
mitosis
Human cells are a _____ target model
multi
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