The ones that need review Flashcards
Concerns in testing:
Bias (experimenter/subject), record of procedure, reproducibility, statistical significance, qualitative/quantitative, correlation/causation
Define: specificity
True pos result from true pos sample
Random error of pH meter:
Contamination, improper mixing, improper reading
Variables for effectiveness of heat killing:
Temp, time, conductance
Autoclave - how does it work? what are the temp/pressure standards?
As pressure is increased, boiling point increases.
As boiling point increases, temperature increases.
15 PSI = 121ºC
T and A equation:
A = log (1/T)
DNA from absorbance equation:
[DNA] = A * dilution factor * 50
Absorbance for bacteria:
595-600 nm
A260/A280 of protein? DNA?
0.55
2, but 1.8 is good
Biuret assay:
Indirect protein assay. Measurement of colour change when CuSO4 reacts with peptide bonds under alkaline solutions. Turns purple (540 nm). Useful to 10 mg/mL.
Thumbs down: takes 15 minutes.
Bradford assay:
Indirect protein assay. Measurement of colour change when Coomassie Blue binds protein. Unbound dye has a max abs of 465 nm; bound dye has a max abs of 595 nm.
Thumbs down: Reaction varies with AA sequence (likes basic ones) and protein function. Upper limit for detection is 1 mg/mL. Dye may precipitate with detergent.
Resolution equation:
R = 0.61 λ / NA NA = n sin θ θ = half the angle that light enters the lens n = refractive index of the medium between subject and lens
Morphologies:
Cocci, bacilli, vibrio, spirochetes, spirillas
Arrangements and groupings:
Pairs (diploboth)
Clusters (staphylococci)
Chains (streptoboth)
Gram pos:
Lots of pep layers.
Teichoic acid makes it negative.
Ex: pneumonia, s. aureus, botulism, anthrax
Gram neg:
One pep layer, one phospholipid layer.
Ex: e. coli, gonorrhea, flu, cholera
Stain: Gram
CV, iodine, acetone, safranin.
Stain: acid fast
For fatty cell walls that repel Gram stains. Primary dye is carbol-fuschin, which has a high affinity for waxy mycolic acids. Decolour with acid-alcohol. Counterstain with methylene blue.
Positive stains red, negative stains blue.
Ex: tuberculosis, leprosy