RT 206 RADIATION EFFECTS TOPIC 1 PREFINALS (copy)

RT 206 RADIATION EFFECTS TOPIC 1 PREFINALS by YJV

1. Atom

2. Molecules

3. Organelles

4. Cells

5. Tissues

6. Organs

7. Organ System

8. Organism/Human

Biological Hierarchy Order:

Deterministic

Threshold

High dose radiation

Non Linear

Early Effects

Stochastic

Non threshold

Low dose of radiation

Late Effects

Linear

Threshold

A specific dose is needed to achieve respone

Non-Threshold

Any dose produces response

Linear

Response is proportional to dose

Non-Linear

Response is not proportional to dose

Cataracts

Erythema

Sterility

Examples of Deterministic:

Cancer

Genetic Mutation

Examples of Stochastic:

Main-Chain Scission

Cross-Linking

Point Lesion

IRRADIATION OF MACROMOLECULES:

Main-Chain Scission

Breakage of the backbone the long chain macromolecule

= Reduction into many smaller molecules (still considered as macromolecule)

=↓ Size ↑ Viscosity

Cross-Linking

Spurlike side structures that extend off the main chain

= Side structures that behave like sticky substance on the end and attach neighboring macromolecule or another segment of the molecule

= ↑ Viscosity

Point Lesion

Result in disruption of single chemical bonds

= Are not detectable but can cause minor modification which in turn can cause malfunction in the cell

1. Main-Chain Scission with only one side rail severed

2. Main-Chain Scission with both side rail severed

3. Main Chain Scission with cross-linking

4. Rung Breakage causing separation of bases

5. Change in or loss of a base

RADIATION RESPONSE OF DNA:

Point Mutation

Chromosomal Aberration

2 Forms of Genetic Mutation:

Point Mutation

Small Scale

Alteration that occurs in the DNA base sequence of a gene

Single gene alteration

Chromosomal Aberration

Larger Scale

Alteration in the structure of the chromosome of the organism

Many gene alterations

After irradiation

Chromosomal Aberrations are the structural changes to the chromosome __________

Aberrations, Lesions, or Anomalies

Chromosomal Aberrations can be called:

Karyotype

Is a chromosome map used for cytogenetic analysis of chromosomes.

Metaphase

Photomicrographs are taken during _____ that demonstrates each chromosome separately

1. Single-Hit Chromosomal Aberration

2. Multi-Hit Chromosomal Aberrations

2 Forms of Chromosomal Aberrations:

Chromatid deletion

If irradiation occurs in G1, a breakage in the chromosome will occur, termed as __________

form a chromosome

During S phase, both the remaining chromosome and deletion will be duplicated to ____________

isochromatids

During Metaphase, this will appear as a normal chromosome with materials missing from the ends of two sister chromatids and two acentric fragments called

one arm or both

If the irradiation occurs in G2, a chromatid deletion may occur in just _________

ring chromosome

If irradiation occurs in G1, If two hits occur on one chromatid, a ________ will be produced

dicentric chromosome

When neighboring chromatids each suffer one hit and recombine, this will produce _________

occur, rare

During G2 phase of the cell cycle, similar chromosomal abnormalities can _____ but are ______

Reciprocal Translocation

Multi-hit chromosomal Aberrations,

If chromosomes experience this type of alteration, they do not lose any genetic material, but instead the genes become rearranged.

sequenced incorrectly

In Reciprocal Translocation, This results in all genetic codes being available, but __________

Before DNA

Chromosomal Aberration is chromosomal damage that occurs ____ synthesis

Chromatid Aberration

Chromosomal Damage that occurs AFTER DNA synthesis

1. It can be delayed from going through division

2. It can die before it divides

3. It can die when attempting mitosis

One of the three things can happen to a cell after irradiation:

Mitotic Delay

Dose Dependent Response

Temporary postponement of cell division after irradiation

Cells under mitosis during time of irradiation completes division while those under G2 are delayed to avoid catastrophic mitosis

catastrophic mitosis

In Mitotic Delay, Cells under mitosis during time of irradiation completes division while those under G2 are delayed to avoid __________

Longer Delay, Lower Dose

Higher Dose = ????

??? = Shorter Delay

Higher Dose, Shorter Delay

???? = Longer Delay

Lower Dose = ????

Interphase Death

Death BEFORE the cell enters mitosis

Rapid Cell Death

Occurs even before the cell tries to divide

Apoptosis

Apoptosis

“falling off” (g)

programmed self-destruction

Mitotic Death

Death DURING/AFTER the cell enters mitosis

“Reproductive Death”

Delayed Cell Death

Misrepair of DNA and Errors accumulate

fails to divide properly

produce nonviable daughter cells

Mitotic Death occurs due to sufficient DNA damage:

MEMORIZED

MEMORIZE THE IMAGE OKAY???

G0

cell cycle arrest

G1

Cellular contents, excluding the chromosomes are duplicated

S

Each of the 46 Chromosomes is duplicated by the cell

G2

The cell “double checks” the duplicated chromosomes for error, making any needed repairs

Single Chromatid

in G1, Each Chromosome is a ________

Pair of sister chromatids

After S phase, Each chromosome is now a __________

Single-Hit Chromosomal Aberration

If irradiation occurs in G1, a breakage in the chromosome will occur, termed as chromatid deletion.

During S phase, both the remaining chromosome and deletion will be duplicated to form a chromosome

During Metaphase, this will appear as a normal chromosome with materials missing from the ends of two sister chromatids and two acentric fragments called isochromatids

If the irradiation occurs in G2, a chromatid deletion may occur in just one arm or both

Multi-Hit Chromosomal Aberrations

If irradiation occurs in G1, If two hits occur on one chromatid, a ring chromosome will be produced

When neighboring chromatids each suffer one hit and recombine, this will produce dicentric chromosome

During G2 phase of the cell cycle, similar chromosomal abnormalities can occur but are rare

Interphase Death

Mitotic Death

Cell Death