Micro lab quiz 2

What are the 5 I's of Microbiology?

Inoculation, Incubation, Isolation, Inspection, Identification

What is inoculation in microbiology?

Introducing microorganisms into media

What is incubation in microbiology?

Growing microorganisms under suitable conditions

What is isolation in microbiology?

Separating microorganisms into pure cultures

What is inspection in microbiology?

Observing microbial characteristics

What is identification in microbiology?

Determining the identity of a microorganism

What is the purpose of aseptic technique?

Prevent contamination and maintain pure cultures

What is the hottest part of a flame?

Tip of the inner blue cone

How should an inoculating loop be sterilized?

Heat until the entire wire glows orange

Why must the inoculating loop cool before use?

To prevent killing bacteria

What is an inoculum?

Microorganisms introduced into media

What does sterile mean?

Free of microorganisms

What is the purpose of heat fixing?

Attach bacteria to the slide

What is a disadvantage of heat fixing?

Can distort cell size and shape

What is the order of objective lenses?

4x, 10x, 40x, 100x

Which objective is the scanning objective?

4x

Which objective is the low dry objective?

10x

Which objective is the high dry objective?

40x

Which objective is the oil immersion objective?

100x

Which objectives can use coarse adjustment?

4x and 10x

Which objectives use only fine adjustment?

40x and 100x

What is the purpose of immersion oil?

Improve resolution and image quality

What is an important rule for oil immersion?

Never return to the 40x objective after adding oil

What is the purpose of a simple stain?

Determine cell shape, size, and arrangement

How many dyes does a simple stain use?

One

What dye is used in a simple stain?

Crystal violet

What is the result of a simple stain?

All cells appear purple

What is the purpose of a Gram stain?

Differentiate gram-positive and gram-negative bacteria

What is the first step in a Gram stain?

Crystal violet

What is the second step in a Gram stain?

Iodine

What is the third step in a Gram stain?

Alcohol

What is the fourth step in a Gram stain?

Safranin

What is the primary stain in a Gram stain?

Crystal violet

What is the mordant in a Gram stain?

Iodine

What is the decolorizer in a Gram stain?

Alcohol

What is the counterstain in a Gram stain?

Safranin

What color do gram-positive bacteria appear?

Purple

What color do gram-negative bacteria appear?

Pink

Why are young cultures preferred for Gram stain?

Provide more reliable results

What is the purpose of an acid-fast stain?

Identify Mycobacterium and Nocardia

What is mycolic acid?

Waxy lipid in acid-fast bacterial cell walls

What is the primary stain in an acid-fast stain?

Carbolfuchsin

What is the decolorizer in an acid-fast stain?

Acid-alcohol

What is the counterstain in an acid-fast stain?

Methylene blue

What is the result of an acid-fast positive test?

Red or pink cells

What is the result of an acid-fast negative test?

Blue cells

What are examples of acid-fast bacteria?

Mycobacterium and Nocardia

What is the clinical use of an acid-fast stain?

Diagnose tuberculosis and leprosy

What is the purpose of a negative stain?

Observe true size, shape, arrangement, and capsules

What dye is used in a negative stain?

Nigrosin

Does a negative stain require heat fixing?

No

Why is a negative stain called negative?

The background is stained instead of the cells

What is an advantage of a negative stain?

Shows true cell size and shape

What do acidic dyes stain?

Background

What do basic dyes stain?

Cells

What is the purpose of an endospore stain?

Detect endospores

What are endospore-forming genera?

Bacillus and Clostridium

What is the primary stain in an endospore stain?

Malachite green

What is the counterstain in an endospore stain?

Safranin

What is the purpose of steam in an endospore stain?

Helps stain enter the spore

What color do endospores appear?

Green

What color do vegetative cells appear?

Pink or red

What is the function of an endospore?

Survival during harsh conditions

What are the physical states of media?

Liquid, semi-solid, solid

What is an example of liquid media?

Nutrient broth

What is an example of semi-solid media?

Motility medium

What is an example of solid media?

Nutrient agar

What is agar?

Seaweed-derived solidifying agent

What is gelatin?

Collagen-derived solidifying agent

What is the autoclave temperature?

121°C

What is the autoclave pressure?

15 psi

What is the autoclave time?

15 minutes

Why are Petri dishes inverted?

Minimize condensation

What is general purpose media?

Supports growth of many microorganisms

What are examples of general purpose media?

Nutrient agar, Nutrient broth, TSA

What is enriched media?

Contains extra nutrients for fastidious organisms

What are examples of enriched media?

Blood agar and Chocolate agar

What is a fastidious organism?

Organism requiring special nutrients to grow

What is selective media?

Inhibits some microorganisms while allowing others to grow

What is differential media?

Distinguishes microorganisms based on visible reactions

What are keywords for selective media?

Inhibit, Restrict, Isolate

What are keywords for differential media?

Detect, Distinguish, Determine, Identify

What is EMB agar?

Selective and differential medium

What does EMB select for?

Gram-negative bacteria

What does EMB differentiate?

Lactose fermentation

What is the appearance of E. coli on EMB?

Green metallic sheen

What is PEA agar?

Selective medium

What does PEA allow growth of?

Gram-positive bacteria

What does PEA inhibit?

Gram-negative bacteria

What is MSA?

Mannitol Salt Agar

What does MSA select for?

Staphylococci

Why is MSA selective?

High salt concentration

What indicates positive mannitol fermentation?

Yellow medium

What indicates negative mannitol fermentation?

Red or pink medium

What is MacConkey agar?

Selective and differential medium

What does MacConkey select for?

Gram-negative bacteria

What does MacConkey differentiate?

Lactose fermentation

What is the appearance of lactose fermenters on MacConkey?

Pink or red colonies

What is the appearance of non-lactose fermenters on MacConkey?

Colorless colonies

What is a colony?

Visible mass of growth from a single bacterial cell