Radiation Damage and Subcellular Targets Quiz

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Questions and Answers

Which type of cell division results in two genetically identical daughter cells?

Meiosis

G1 phase

Mitosis (correct)

G2 phase

What is the defining feature of the S portion of the cell cycle?

Chromosome segregation

DNA synthesis (correct)

Cell division

Metabolic processes

During which phase of the cell cycle is DNA synthesized but other metabolic processes are taking place?

M phase

G1 phase

G2 phase (correct)

S phase

Which period of the cell cycle is not characterized by DNA synthesis?

M phase Signup and view all the answers

During which phases of the cell cycle are cells most radio-sensitive?

M and G2 phases Signup and view all the answers

What characterizes the cell cycle time for stem cells in certain tissues?

Up to 10 days Signup and view all the answers

Which of the following is true about the adaptive response to radiation?

It results in a lower than expected number of chromosomal aberrations following a second dose. Signup and view all the answers

How does oxygen tension affect cell sensitivity to low LET radiation?

Cells with normal concentrations of oxygen tend to be 2-3 times as sensitive to low LET radiation as hypoxic cells. Signup and view all the answers

What is the purpose of radioprotective drugs?

To reduce the effective dose of radiation when injected prior to an acute exposure Signup and view all the answers

What are chemical agents that reduce cell response to radiation called?

Radioprotectors Signup and view all the answers

Why do females tend to be slightly more radioresistant than males?

Variability in female hormonal levels reduces lymphocyte radiosensitivity. Signup and view all the answers

According to age, which group is the most radio-sensitive?

Fetus Signup and view all the answers

What is the most important site of damage in a cell due to radiation?

DNA Signup and view all the answers

Which type of radiation usually causes isolated DNA damage?

Low LET radiation Signup and view all the answers

What is more complex and harder to repair than isolated damage?

Double strand breaks Signup and view all the answers

What type of DNA damage is typically repaired using base-excision repair mechanisms?

Base damage Signup and view all the answers

What are the possible outcomes of cell irradiation mentioned in the text?

Division delay, reproductive failure, cancer, genomic instability Signup and view all the answers

What type of effects are suffered by individuals during their lifetime due to radiation?

Somatic effects Signup and view all the answers

Which type of effects from radiation exposure have a probability of occurrence that increases with dose but no relation to severity?

Stochastic effects Signup and view all the answers

What type of radiation-induced effects are highly predictable, with a threshold dose that triggers a dose-dependent response?

Deterministic effects Signup and view all the answers

What is represented by the shoulder on the cell survival curve?

DNA repair mechanism Signup and view all the answers

Which type of radiation can result in more complex DNA damage, making repair more difficult?

High LET radiation Signup and view all the answers

When is cell death most sensitive to radiation?

During the mitotic phase and late G1 Signup and view all the answers

What may low doses of radiation initiate that reduces the consequences of subsequent exposures?

Adaptive responses Signup and view all the answers

Which type of radiation can be shielded with Plexiglas?

Beta particles Signup and view all the answers

What is the term used to describe the amount of energy imparted locally in a target by radiation?

Linear Energy Transfer (LET) Signup and view all the answers

Which radiation type has the highest ability to penetrate materials?

Gamma rays Signup and view all the answers

Which effect of radiation involves a transfer of energy from the radiation directly to the target molecule, typically DNA?

Direct radiation effects Signup and view all the answers

What can lead to tissue damage, with an estimated two-thirds of the biological damage caused by low LET radiation being due to indirect action?

Reactive oxygen species (ROS) Signup and view all the answers

What is believed to be particularly important in producing biological damage by the indirect action of x-rays?

Hydroxyl radicals Signup and view all the answers

Study Notes

Cell death for stem cells and other cells with high division capacity is referred to as reproductive death.
Apoptosis is a process by which an organism induces cells that may pose a threat to commit suicide.
Apoptosis can be induced by radiation, which is generally a good thing since dead cells don't become cancerous.
Failure of apoptosis can increase the probability of malfunctioning cancerous cells proliferating if radiation damages the genes that induce apoptosis.
Radiation is classified into two main categories: non-ionizing and ionizing.
Ionizing radiation can be further divided into directly ionizing (charged particles) and indirectly ionizing (neutral particles) radiation.
Ionizing radiation has the ability to penetrate and transfer energy to the material it is penetrating. The term "Linear Energy Transfer" (LET) is used to describe the amount of energy imparted locally in a target.
Alpha particles have a high LET, low penetrating ability, and can be shielded by a piece of paper.
Beta particles have a low LET and can only penetrate low-density materials, they can be shielded with Plexiglas.
X-rays and gamma rays have a low LET and the highest ability to penetrate materials. High-density materials are needed to shield against these waves.
X-rays interact with atoms through the photoelectric effect, Compton scattering, or pair production, resulting in the production of free radicals that can damage DNA.
Direct radiation effects involve a transfer of energy from the radiation directly to the target molecule, typically DNA. These effects are most important for high LET radiation.
Indirect radiation effects occur when radiation produces free radicals that react with the target molecule, typically DNA. These effects are most important for low LET radiation.
Indirect radiation effects can be modified by chemical sensitizers or radiation protectors.
Ionizing radiation interacts with water, leading to the production of free radicals that can damage DNA and other molecules.
The presence of an excess of oxygen during irradiation of cells allows the formation of additional free radicals.
Much of the damage caused by radiation is believed to be due to oxygen containing radicals, ions, and peroxides collectively known as reactive oxygen species (ROS).
The hydroxyl radicals are believed to be particularly important in producing biological damage by the indirect action of x rays.
Radiation leads to tissue damage, with an estimated two-thirds of the biological damage caused by low LET radiation being due to indirect action.
Radiation-induced malignancies can occur if the radiation directly affects somatic cells and alters the DNA (and hence the chromosomes) as a result.

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Test your knowledge of radiation-induced damage to subcellular targets such as DNA and membranes. Explore the effects of radiation on reproductive stem cells and the potential for congenital abnormalities.