Chapter 7: Molecular and Cellular

Radiation damage is observed on which of the following three levels?

Molecular, cellular, and organic systems

Molecular damage results in the formation of structurally

Changed molecules that may severely impair cellular function

According to the target theory, if only a few non-DNA cell molecules are made dysfunctional by radiation exposure, the cell will probably

Not display any evidence of injury after irradiation

Each cell’s function is governed and defined by the structures of its constituent molecules. If these structures are altered by radiation exposure, the following may result

1. Disturbance of the cell’s chemical balance

2. Disturbance of the cell operation

3. Failure of the cell to perform normal tasks

1, 2, and 3

Chromosome aberrations result when irradiation occurs

Early in interphase

Which of the following are examples of distorted chromosomes

1. Anaphase bridges

2. Dicentric chromosomes

3. Ring chromatids

1 and 3 only

Which of the following is useful for explaining cell death and nonfatal cell abnormalities caused by exposure to radiation ?

Target theory

X-rays and gamma rays can be referred to as “streams of particles” called photons because of a property known as

Wave-particle duality

The random interaction of x-rays with matter produces a variety of structural changes in biologic tissue, including

1. A single-strand break in one chromosome

2. More than one break in the same chromosome

3. Stickiness, or clumping together, of chromosomes

1, 2, and 3

Why are repair enzymes usually able to reverse the cellular damage generally caused by low-level ionizing radiation?

Damage to DNA is sublethal

What governs the radiation dose required to cause apoptosis?

The radiosensitivity of the individual cell

Which of the following is the ratio of the radiation dose required to cause a particular biologic response of cells in an oxygen-deprived environment to the radiation dose required to generate an identical response under normal oxygenated conditions?

Oxygen enhancement ratio

Which of the following is a method of displaying the sensitivity of a particular type of cell to radiation?

Cell survival curve

Where are lymphocytes manufactured in the human body?

Bone marrow

Which of the following defines the ratio of the dose of a reference radiation (conventionally 250-kVp x-rays) to the dose of radiation of the type in question that is necessary to produce the same biologic reaction in a given experiment?

RBE

A biologic reaction is produced by 6 Gyt of a test radiation. It takes 36 Gyt of 250-kVp x-ray radiation to produce the same biologic reaction. What is the RBE of the test radiation?

6

A hydroperoxyl radical (HO2) is formed when a hydrogen free radical (H) combines with

Molecular oxygen (O2)

The LET value of radiation is an essential factor in

Assessing potential tissue and organ damage from exposure to ionizing radiation

Because high-LET types of radiation deposit more energy per unit length of biologic tissue traversed, they are

More destructive to biologic matter than low-LET radiation

Ring chromosomes, dicentric chromosomes, and anaphase bridges are examples of

Distorted chromosomes