Ch2 Irradiation damage Flashcards
Raditation damage to cells charcteristics (4)
- Interaction of radiation in cells is a chance
- Visible changes in the cell are not unique
- Energy is deposited quickly and randomly in the cell
- Biological changes occure only after a period of time (latent period)
What is the target of basic interactions
DNA
What are the basic interaction (2)
- Direct hit
- Indirect hit
What is direct hit interaction
When DNA is ionized
What is indirect hit interaction
Involves bonding with ions and free radicals
DNA strand is made up of (3)
- Nitrogenous base
- Sugar
- Phosphoric acid
What are the DNA damage types (4)
- base damage
- Single strand break
- Double strand break
- Crosslinks
Changes in DNA are reflected in ___
Chromosomes
Chromatid aberrations are produced when cells are irradiated ___ ___ ___
After DNA synthesis
Chromosome aberrations are produced when cells are irradiated ___ ___ ___
Before DNA synthesis
Describe single strand break
Break in one strand of DNA molecule. A supporting structure (base) is stripped away
Describe double strand break
- Breaks in both backbones of DNA
- Strand snaps in 2 pices
- Most important lesion produced by radiation***
Double strand break results (3)
- Treated as single strand break if
- May result in ___ or ___
- Significant for ___ ___
- Breaks are non adjacent or in proximity
- Mutation, carcinogenesis
- Cell kill
Base damage description
The loss or change of a base (A,G,T,C) on the DNA strand
Base damage result (2)
- Changes sequence of bases — Changes genetic info — mutation
- Cell death
Crosslinking DNA
- description
- Results
- Bonds formed between 2 regions of the same strand, from one DNA to another and one DNA to a protein
- Unclear significance to cell kill
What are the three changes to chromosomes
- Restitution
- Aberration
- Rearrangement
What is chromosome restitution
Broken ends rejoin with no visible damage
Chromosome aberration is when
part of the chromosome is lost at the next mitosis
What is chromosome rearrangment
when Broken ends cause mutations and loss of genetic material
A change in chromosomes means a change in ___ reslulting in changes in ___ ___
- DNA
- Genetic material
What are acentric and dicentric chromotid rings
- ___ is broken into ___ fragments
- 2 with ___ and 2 ___
- Chromosme, 4
- centromeres, without
Ring chromosomes
- One break…
- Two ends…
- in each arm of same chromosome
- join together forming a ring
chromosome stickiness
- chromosomes clump together during ___
- Cant ___ and go to seperate ___
- Metaphase
- Seperate, spindles
Effects on somatic cells may have a
clnical impact
Effects on germ cells producing genetic mutations may be carried over
to new generation
Dicentric fragments have ___ centromeres
2
Ancentric have ___ centromeres
No
Ring chromosomes
- Ring is replicated and …
- Replicated rings are ___ and ___ becomes impossible resulting in ___ ___
- transmitted to a daughter cell
- Intertwined, anaphase, cell death
Loss of a part (deletion) results in ___ fragmenation
Acentric fragmentation
Rearangement of broken ends result in (4)
- Ring
- Dicentric
- Anaphase bridge
- chromosomes
Rearangement of broken ends WITH NO VISIBLE DAMAGE result in (2)
- Genertic mutations
- Inheritable characteristics
Translocations are formed by
A break in the arms of 2 different chromosomes
Symmetrical Translocation
- Lethal?
- Associated with
- Activates a
- No
- Several malignancies
- Oncogene
Deletion formed by
2 breaks in the same arm of a chromosome, a fragment is deleted creating a short and long arm
Deletion
- lethal?
- Associated with
- No
- Carciogenesis of lost genetic material including a supressor gene
Inversion
2 breaks in the same arm of a chromosome, a fragment is fliped flopped on the same arm and location
___ is the most commonly muted tumor suppressor genes controlling
apoptosis
P53
