MicroBio LAB Quiz Guide

Question 1

What is Sub-Culturing?

Answer 1

Microorganisms transferred from one medium to another by subculturing

Question 2

Streak plate method

What are we looking for?

What does it indicate?

Question 3

Microscopy

Parfocal, Oil Immersion

Question 4

Aseptic techniques

Answer 4

Wash hands before and after handling samples

Sterilize equipment

Disinfect workspace before and after

Flame sterilize instruments

Question 5

Preparation of bacterial smears

Answer 5

Place 1-2 drops of distilled water on the center of the slide using loop

Transfer small amount of bacteria from culture into drop of water

Allow smear to air dry

Heat fixation – Quickly pass the smear 2-3 times over Bunsen burner flame; fixes bacterial proteins to glass surface

Question 6

gram stain

Answer 6

Crystal violet, primary stain
Gram’s Iodine, Increases intensity of primary stain
Ethanol/Acetone, decolorizing agent
-Can’t do too much, or too little
-Cells w/ thick peptidoglycan layer hold on to initial color
-Opposite for Gram Neg
Safranin, counterstain pink for decolorized cells

Question 7

Nutritional requirements

Answer 7

Chemically defined
-Inorganic, synthetic
-Amount of each nutrient is known

Complex
-Exact composition of media is not known
-Made of extracts from plate and animal tissues
-Good for fastidious (picky, high nutrient requirement) organisms

Question 8

Temperature classifications

Answer 8

Psychrophiles: -5 to 20 Celsius
Mesophiles: 20 to 45 Celsius
Thermophiles: 35 degrees and above

Question 9

Differential/Selective media

Answer 9

Selective – Isolate a specific group of bacteria

Differential – Distinguish between bacteria of the same group

Question 10

Study all the biochemical tests- know the substrates, enzymes, end products, media, and any reagents added. Understand how to interpret the results.

Question 11

Starch and Lipid Hydrolysis