Questions and Answers
What is cytogenetic damage?
Radiation-induced structural change in chromosomes.
What is a point mutation?
Radiation damage that consists of a molecular lesion of the DNA and causes genetic mutation.
What does target theory state?
The radiobiologic theory that says for a cell to die, after radiation exposure, its target molecule must be inactivated.
What does viscosity determine in a solution?
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What is crosslinking?
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What is a radiation hit?
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What is a stochastic effect?
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List the effects of irradiation of macromolecules in solution in vitro.
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How is solution viscosity used to determine macromolecular damage?
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What is the difference between catabolism and anabolism?
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In what phase of the cell cycle does the DNA ladder in the middle of each rung consist of only a single chain?
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Name the three principal observable effects of DNA irradiation.
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Differentiate among transcription, transfer, and translation.
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Write the formula for radiolysis of water in which the atom of water is ionized.
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What happens to radiation-induced free radicals within the cell?
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Describe the molecular cause of a deterministic effect.
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What happens to the quantity of DNA as the cell progresses from G1 to G2?
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Chromosome aberrations are an example of what type of cell damage?
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What happens when a single nucleotide base is lost?
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What is the result of the equation H2O + Radiation?
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What does HOH+ dissociate into?
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What does HOH− dissociate into?
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What molecular change results in a stochastic effect?
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Describe the characteristics of a free radical.
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What is the difference between direct effect and indirect effect?
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How much DNA is in a cell?
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Study Notes
Cytogenetic Damage and DNA Mutations
- Cytogenetic damage refers to radiation-induced structural changes in chromosomes.
- Point mutation involves a molecular lesion in DNA that leads to genetic mutation.
Radiation Interaction and Effects
- Target theory states that for a cell to die post-radiation exposure, its target molecule must be inactivated.
- Stochastic effects relate to the probability of biological responses to radiation increasing with dose, with no specific dose threshold.
Macromolecular Changes Due to Irradiation
- Effects of irradiation on macromolecules include main chain scission, cross-linking, point mutations, and changes in viscosity.
- Viscosity increases after high radiation doses, helping assess the degree of damage in macromolecules.
Catabolism vs. Anabolism
- Catabolism involves breaking down large molecules into smaller ones, while anabolism constructs large molecules from smaller units.
Cell Cycle and DNA Characteristics
- In the synthesis (S) phase of the cell cycle, the DNA ladder consists of open links on a single chain.
- As cells progress from G1 to G2, parent DNA replicates into two duplicate daughter molecules, effectively doubling the DNA content.
Principles of Molecular Genetics
- DNA's genetic code is transcribed by mRNA, transferred to tRNA, and translated into proteins during gene expression.
Radiolysis of Water
- Radiolysis of water involves the ionization of water molecules, producing HOH+ and an electron: H2O + energy = HOH+ + e−.
Free Radicals and Cell Damage
- Radiation-induced free radicals migrate within cells, transferring energy to target molecules and subsequently neutralizing by joining with other molecules.
- Free radicals are unstable, highly reactive entities that can disrupt bonds, causing point lesions distantly from the original ionizing event.
Deterministic Effects and Cell Damage
- Deterministic effects result from specific target sites on molecules being hit, causing cell death.
- Cytogenetic damage includes chromosome aberrations indicative of structural changes from radiation exposure.
Molecular Changes and DNA Quantity
- Loss of a single nucleotide base destroys the triplet code, resulting in a point mutation.
- Radiation can dissociate water molecules into ions: HOH+ yields H+ and OH*, while HOH− yields OH− and H*.
Understanding Direct vs. Indirect Effects
- Direct effects of radiation involve interactions with DNA, while indirect effects occur through interactions with other molecules that form free radicals affecting DNA.
Overview of DNA in Cells
- DNA is present in limited quantities within the cell, highlighting its critical role in genetic information storage and transfer.
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Description
Explore key concepts in radiobiology with these flashcards from Chapter 31 of Bushong. Learn about cytogenetic damage, point mutations, and target theory in relation to radiation exposure. Perfect for students seeking to reinforce their understanding of radiation effects on cellular structures.