Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
9 Cards in this Set
- Front
- Back
|
Chemical Mutagen
|
A chemical that acts like a base causing the base to call the wrong pairing partner
|
|
|
The Mechanism of Action of DNA Damage by non-ionizing Radiation
|
DNA absorbs photons of UV light which results in reorganization of covalent bonds, particularly in adjacent thymines
This creates a thymine dimer which distorts the helix Dimers are fatal to the cell because the cell can't transcribe their DNA However, at this point this is only DAMAGE, it is not yet a MUTATION |
|
|
Mechanism of DNA Repair by Enzymes
|
1) Photolyase: Repairs dimers from UV light. It is driven by white light.
2) Endonucleases: Recognize distortion, makes a nick on both sides of the dimer so it can be removed and replaced. Ligase seals the nicks and then everything is back to normal. This process is error prone which leads to mutation. The more you have to repair, the more chance of mutation. |
|
|
Why are tanning beds bad?
|
Exposure to UV without sunlight
The only way to repair the dimers is through endonucleases |
|
|
DNA Damage by Ionizing Radiation
|
Unstable nuclei decay and produce high energy photons that ionize molecules in cells
The photon smashes into water to create reactive oxygen Reactive oxygen can oxidize bases and break DNA *Iodine Tablets: Go to the thyroid (where iodine is concentrated) and compete with the radioactive iodine |
|
|
Production of Aneuploid Gametes During Meiosis
|
Down syndrome incidence spiked in Balarus 9 months after exposure to radiation from Chernobyl
Therefore, exposure to radiation may mess up meiotic segregation MAYBE exposure to radiation effects the cytoskeleton and creates the aneuploid/unbalanced gametes and karyotypes/mutations *Also: data suggests increases in thyroid cancer in adolescents (maybe) because they were developing at the time of Chernobyl |
|
|
Chromosomal Level Mutations
|
Ionizing radiation breaks chromosomes and the cells attempt to fix the damage is not perfect
Translocation: A piece of one chromosome is swapped with a piece of another chromosome...Not a huge deal ...UNLESS translocation occurs on chromosome 8 and 14 |
|
|
The Significance of Chromosomes 8 & 14
|
Chromosome 14: Antibody genes with powerful promoters and enhancers, and when you need antibodies you need A LOT of them
Chromosome 8: MYC gene that drives cell division *Translocation Result* A chromosome with a big enhancer promoting driving MYC Massive expression of a gene that drives cell division AKA lymphoma |
|
|
Oncogene
|
MYC
When deregulated, results in cancer due to uncontrolled cell division |
