UV Radiation & Yeast Genetics Flashcards
Miotic recombination
The combination of parental genes not found in the parent organisms through mitosis (often result of radiation)
Radiobiology of Yeast
A lethal dose of radiation only needs to raise the temperature of a cell by a small fraction of one degree
Reason: DNA is very susceptible to radiation damage and is amplified by replication and growth
This: mechanisms to repair radiation damage evolved in cells early history
Ionizing radiation
(Xrays, radioactivity) ionize molecules at random throughout cells (severe damage breaks covalent bonds)
UV Radiation
Absorbed by specific molecules
“Target”
Cell components most sensitive to damage (DNA)
Types of Damage ionizing radiation
Ionizing radiation: Separates or breaks double stranded structure of DNA (no replication)
Type of Damage UV
Selectively absorbed by purine and pyrimidines bases (most concentrated radiation)
UV radiation forms dimmers
Radiation repair
Before too much O2 and O3 production greater radiation
Photoreactivation
When UV damaged cells are exposed to visible light. They use the energy to produce enzymes that reverse the formation of dimmers
Excision repair
Sequence of events that remove damaged DNA then resynthesize the missing portions (mutations often occur during messed up resynthesis of DNA)
Reproductive death
When a cell can’t divide to form visible offspring
Metabolic death
When a cells are killed outright
Radiation effects
Risk of cancer
Mutations
Stimulation of genetic recombination
Measure of Irradiated Cells
It’s easier to count living cells than dead cells
Lethal Effects of Radiation
DNA damage not repaired before DNA replication (cell does)
Reproductive Death
Metabolic Death
