The ones that need review

Question 1

Concerns in testing:

Answer 1

Bias (experimenter/subject), record of procedure, reproducibility, statistical significance, qualitative/quantitative, correlation/causation

Question 2

Define: specificity

Answer 2

True pos result from true pos sample

Question 3

Random error of pH meter:

Answer 3

Contamination, improper mixing, improper reading

Question 4

Variables for effectiveness of heat killing:

Answer 4

Temp, time, conductance

Question 5

Autoclave - how does it work? what are the temp/pressure standards?

Answer 5

As pressure is increased, boiling point increases.
As boiling point increases, temperature increases.

15 PSI = 121ºC

Question 6

T and A equation:

Answer 6

A = log (1/T)

Question 7

DNA from absorbance equation:

Answer 7

[DNA] = A * dilution factor * 50

Question 8

Absorbance for bacteria:

Answer 8

595-600 nm

Question 9

A260/A280 of protein? DNA?

Answer 9

0.55

2, but 1.8 is good

Question 10

Biuret assay:

Answer 10

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.

Question 11

Bradford assay:

Answer 11

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.

Question 12

Resolution equation:

Answer 12

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

Question 13

Morphologies:

Answer 13

Cocci, bacilli, vibrio, spirochetes, spirillas

Question 14

Arrangements and groupings:

Answer 14

Pairs (diploboth)
Clusters (staphylococci)
Chains (streptoboth)

Question 15

Gram pos:

Answer 15

Lots of pep layers.
Teichoic acid makes it negative.
Ex: pneumonia, s. aureus, botulism, anthrax

Question 16

Gram neg:

Answer 16

One pep layer, one phospholipid layer.

Ex: e. coli, gonorrhea, flu, cholera

Question 17

Stain: Gram

Answer 17

CV, iodine, acetone, safranin.

Question 18

Stain: acid fast

Answer 18

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

Question 19

Glycocalyx:

Answer 19

Sugars and proteins. Increases pathogenicity. May produce biofilms, which can help bacteria stick to a surface.
Ex: S. mutans and plaque (calcified capsules)

Question 20

Negative stain:

Answer 20

Allows visualization of the glycocalyx. Nigrosin dye is bulky and negative charged so it doesn’t stick to bacteria. Thin film prep without fixing cells. Additional staining (CV) needed to visualize bacteria.

Question 21

Leifson stain:

Answer 21

For thickening the flagellum.

CV and a mordant.

Question 22

WHICH BACTERIA MAKE ENDOSPORES?

Answer 22

Gram pos. Bacillus (anthrax, insecticides) and clostridium (tetanus, botulinum, gangrene)

Question 23

Endospore stain:

Answer 23

Visualization of endospores. Malachite green is steamed into the endospores. Counterstain with safranin.

Question 24

What do aerobes do with free radicals?

Answer 24

Detoxify them with catalase

Question 25

Characteristics of agar - temperatures

Answer 25

Solidify at 40, melt at 85.

Question 26

MacConkey agar:

Answer 26

Selects against Gram pos using salts and CV. | Differential for lactose fermentors (pos = purple).

Question 27

Mannitol salt agar (MSA):

Answer 27

Selective with high salt concentration. Differential for alcohol fermentation (pos = yellow). Useful for S. aureus.

Question 28

Blood agar:

Answer 28

Enrichment and differential. | Hemolysis - alpha (discolouration), beta (clearing), gamma (none).

Question 29

Saboraud dextrose agar:

Answer 29

High glucose. Selective for yeasts and molds bc high sugar and acidic pH.

Question 30

SIM deep:

Answer 30

Differential. Sulfur reduction: pos = black. Indole production: add Kovak, pos = pink/red Motility

Question 31

Oxidase assay:

Answer 31

Tests for cytochrome 3 oxidase (making ATP using O2). Pos = purple.

Question 32

Catalase assay:

Answer 32

Tests for catalase (H2O2 into water and oxygen). Pos = bubbles.

Question 33

Biochemical identification using DNA:

Answer 33

PCR. Use a primer that binds a specific DNA species.

Question 34

Antibiotic target: cell wall inhibitor

Answer 34

Penicillin and cephalosporins. Natural penicillin only works on gram neg. All contain beta-lactam ring. Bind and inhibit transpeptidases in the periplasmic space. LYSIS.

Question 35

Antibiotic target: protein synthesis inhibitor

Answer 35

Interfere with ribosome/mRNA/tRNA complex. Ex: chloramphenicol (broad), streptomycin (gram neg), neomycin (topical streptomycin), tetracycline (broad). STASIS.

Question 36

Side effects of protein synthesis inhibitors

Answer 36

Chloramphenicol can poison mitochondria and cause anemia. Bad for babies. Streptomycin can cause deafness. Tetracycline can yellow developing teeth, because it's negatively charged and binds to calcium.

Question 37

Antibiotic target: plasma membrane inhibitor

Answer 37

Polymyxins damage gram neg membranes. (Toxic to neurons and kidneys.) Daptomycin depolarizes gram pos membranes. Polysporin: Polymyxin B and bacitracin inhibit gram pos. Good as topical, not so much otherwise.

Question 38

Antibiotic target: nucleic acid synthesis inhibitor

Answer 38

Rifamycin/rifampin: best against mycobacteria (TB, leprosy). Inhibits mRNA synthesis. Highly permeable because of -OHs and hydrophobicity. Quinolines: inhibit DNA gyrase (replication). Broad spectrum. Ex: ciprofloxin.

Question 39

Antibiotic target: metabolic inhibitor

Answer 39

Sulfonamides. Completely synthetic. Used in WWII to prevent gangrene. Blocked folate, which is used to produce thymine and uracil.

Question 40

CFU and dilution:

Answer 40

1/DF = CFU/mL / desired count * volume plated

Question 41

M-M equation: Km is often..

Answer 41

At phys pH.

Question 42

Km of hexokinase? glycokinase?

Answer 42

30 uM, 10 mM.

Question 43

kcat equation:

Answer 43

kcat = Vmax/[E]t

Question 44

Km of ALDHs:

Answer 44

2: 80 1: 130

Question 45

U:

Answer 45

Catalyzing 1 umol in 1 min

Question 46

Enzyme activity equation:

Answer 46

ΔC/min = reaction volume/enzyme volume | U/V

Question 47

Specific enzyme activity equation:

Answer 47

Activity / [protein]. | U/g