Lab Practical Final Review
What is the UV range Lethal to bacteria?
260 nm is the most germicidal but 4 nm to 400 nm is the most effective range.
What size band will be produced if the gene is present in PCR?
533 bpp
What factors affect the germicidal activity of UV light?
A control. Exposure time.
What is a thymine dimer?
A thymine dimer is when two thymine bases are connected together after exposure to UV light.
Why are exposure times different between the two lab microbes used?
Because Bacillus megaterium is an endospore former, and Staphlococcus aureus is a non endospore former.
What does hemolytic reactions on a Blood Agar plate look like?
Beta: Clearing Alpha: Greenish Brown Gamma: NO change
What is the reaction in a catalase test for Staphlococci
Bubbles.
What test differentiates between Streptococcus and Staphlococcus
Catalase Test
What is a coagulase (+) result?
Clumping
What is Kirby- Bauer method?
Creating a bacterial lawn and placing antibiotic disks on the media and checking for the zone of inhibition to test sensitivity of medication
Name three steps in PCR?
Denature, Anneal, elongation
What toxin is responsible for Beta Hemolysis?
Hemolysin
What are the five characteristics used to distinguish streptococcal species?
Hemolysis patterns on BA plates. Bacitracin Sensitivity. Optochin Sensitivity. Bile Esculin Hydrolysis. Growth in 6.5% NaCl.
What is the purpose of the thermocycler?
It controls the environment for DNA replication allowing denaturing and annealing.
What is the theory and procedure behind PCR?
It is used to copy dna
What is MIC?
Minimum inhibitory Concentration
What is the reaction in a catalase test for Streptococci
No bubbles
What are the advantages and disadvantages of using PCR bs the Kirby-baurer Method for determining antibiotic sensitivity.
PCR Advantages: Fast- Accurate & sensitive. CONS: Expensive. Kirby Baurer - Advantages : Cheap Disadvantages: Time consuming.
What does PCR stand for?
Polymarase chain reaction
What is Bile Esculin Hyrdrolysis ( what type of medium?)
Selective and differential
What is a Mutagen?
Something that creates mutations in the DNA wich causes DNA polymarase to be unable to replicate.
What repair mechanisms do Cells have?
The SOS system which is where it goes in and replicates the parts of DNA that created Dimers
What is the control in the UV Experiment (Exercise 18)
The lid or the index card.
What is the purpose of keeping the plastic petri lid on the plate during exposure?
To block out some of the UV light.
Why do you heat to 94 degrees Celsius for PCR?
To break the hydrogen bonds since helicase isnt present
What is a semi-synthetic antibiotic?
When antibiotics are chemically altered to make them more effective in their mode of action.
What is a bacterial Lawn?
When you swab in different directions all across the agar to form a "Lawn" of colonies.
What would a plate look like with damage with repair vs. damage without repair?
With repair there will be colonies and growth. Without repair, there will not be any growth
What is the role of TAQ polymerase?
Withstand high temps while it attaches nucleotides to the DNA template
What is the role of addition of primers into PCR?
initiates/ detects
What is the name of the gene that confers resistance in MRSA? Name the proteins (initials) that this gene codes for?
mecA & PBP2