Lab 23 + 24 Flashcards
What is non-ionizing radiation
Long wavelengths with less energy
What is ionizing radiation
Short wavelengths with more energy.
How does ultraviolet radiation affect DNA in bacteria
Ultraviolet light induces Thymine dimers in DNA which result in mutation.
Describe light repair
When thiamine dimers are exposed to visible light, photolyases are activated. These enzymes split the dimers restoring the DNA to the undamaged state.
What are the enzymes involved in light repair
Photolyases
What is dark repair
Mechanism independent of light. Dimers are removed by endonuclease, DNA polymerase replaces the nucleotides in DNA ligase seals the sugar phosphate backbone.
Which bacteria had the ability for both light and dark repair
Serratia marcescens and
Micrococcus luteus
Why do we remove the lid when we put the plate under the ultraviolet light
Because UV rays don’t penetrate the plastic
Why would some colonies of bacteria still grow in the areas exposed to ultraviolet light
Due to the fact. That the mutations might not have been a lethal. Also light repair and dark repair can fix some of the mutations
What are antimicrobial agents
Chemicals that control the growth of microbes
What are disinfectants
Chemicals used on inanimate objects to lower the level of microbes on their surface
What are anti-septic’s
Chemicals used on living tissue to decrease the number of microbes
What are bacteriocidal agents
Chemicals that result in bacterial death
What are bacteriostatic agents
Chemicals causing temporary inhibition of growth of bacteria
What is the D RT
Time it takes to kill 90% of the microbial population
