BIO 102 Lab Final Exam

What’s my power?

power of magnification = power of ocular lens x power of the objective

Calculating Magnification

Eye Piece Objective Lens

10x 100x

10x 50x

5x 40x

Magnification

Enlarge objects

Resolution

Distinguish between objects

Contrast

Differences in intensity

What does the oil immersion lens do?

It reduces light scatter, increasing resolution

Simple Stain Cocci

Simple Stain Bacilli

Also referred to as ‘Rod’

Simple Stain Others

Simple Stain Appendaged Bacteria

How does Gram Positive Bacteria Appear?

Blue

How does Gram Negative Bacteria Appear?

Pink/ Red

Blood Agar

Hemolysis

Mannitol Salt Agar

Selective and differential

A) Positive (mannitol fermentation)

B) Inhibit growth

C) Negative

Eosin Methylene Blue

Gram negative

Lactose

Colored colonies

(Picture shows the growth on EMB agar a) gram-positive organism growing poorly due to inhibition by methylene blue in medium b) gram-negative non-lactose fermenter c) coliform lactose fermenter with mucoid pink and purple growth d) E. coli with green sheen caused by rapid lactose fermentation)

MacConkey

Gram negative

Lactose fermentation

colored colonies

Osmotic Pressure

Absorbance via spectrophotometer

Higher absorbance= higher bacterial number= halophilic

Osmotic Pressure

BHI (brain-heart infusion agar)

Ice bath to limit diffusion of oxygen from atmosphere

Creates gradient from high oxygen near surface to low oxygen at bottom

Catalase

Hydrogen peroxide

Catalase = hydrogen peroxide → O2 = bubbles

2H2O2 --catalase→ 2H2O + O2

Oxidase

Oxidase reagent

purple=positive

Aerobic gram negative bacteria

Kirby-Bauer Method

Antibiotic sensitivity

Mueller Hinton Agar (MHA)

Compare measured zone of inhibition to standard table

Sensitive (susceptible), intermediate, resistant

Kirby-Bauer Method

Nitrate Reduction

Nitrate broth

Initial red= positive

Red after Zn^3+ and HCl = negative

DNase

DNase agar
• Add DNA to nutrient
agar
• Test for presence of DNase

DNase results

Starch Hydrolysis

• Starch agar plates
• Testing for amylase
• Iodine

Starch Hydrolysis Results

Phenol Red

• pH indicator
• Glucose, lactose, sucrose
• + = yellow
• Acid production
• Substrate utilization

Phenol Red Results

Litmus Milk

• pH
• Pink = acidic (lactose
fermentation)
• Purple/blue = basic
• White = litmus reduction
• Brown = proteolysis/digestion

Litmus Milk results

IMViC

MRVP
• MR = methyl red
• + = red
• VP = Vogues-Proskauer
• VP reagent A +B
• + = red

Methyl Red Test Results

Vogues-Proskauer Test Results

IMViC

SIM
• Sulfide
• + = black (hydrogen sulfide released when metabolized)
• Indole
• Kovac’s
• + = red
• motility
• Stab semisolid SIM medium
• + = distribution

SIM Results

IMViC

• Citrate utilization
• Simmons citrate
• + = blue

Citrate Utilization Results

Urease

• Urea broth
• Presence of urease
• + = red/pink

Urease Results