Microbiology - Lecture Exam 1

BIO 205: History of Microbiology, Introduction to Microorganisms, Identification and Classification of Bacteria, Prokaryotic Cell Structure, Microbial Growth, and Culturing Microbes.

Gram Positive Bacteria stain what color?

Purple

Gram Negative Bacteria stain what color?

Pink

Robert Hooke

Coined the term “cell” after examining a cork.

Antonio van Leewenhoek

First described fungi, algae, protozoans, and bacteria using lenses he made.

Louis Pasteur

• Created swan-necked flasks

• Experimented with fermentation

Robert Koch

• Developed postulates (protocol) for determining the microbe causing disease

• First pictures of bacteria

• Aseptic techniques

Francisco Redi

Found evidence that disproved spontaneous generation through experiment with fruit flies and meat.

Ignaz Semmelweis

Introduced handwashing to reduce spread of puerperal fever in labor/delivery ward.

Joseph Lister

Developed antiseptic techniques following surgical procedures.

Florence Nightingale

• Cleaned rooms and patient clothes

• Founded first nursing school

John Snow

Mapped cholera outbreak in London

Edward Jenner

Inoculated boy with cowpox (attenuated version of smallpox).

Paul Eherlich

Founded chemotherapy through search for a chemical that would kill all pathogens.

Koch’s Postulates

1. Suspected germ must be present in every case of disease

2. Germ must be isolated and grown in pure culture

3. Germ must cause disease when inoculated

4. Germ must be able to be recultured after inoculation

Fungi

Eukaryotic : cell walls

Molds

Multicellular and have hyphae

Yeasts

Unicellular and reproduce through budding

What are Pseudopodia?

Protozoan cell extensions that flow in direction of travel.

What are Cilia?

Short hairlike structures that can beat to propel motion.

What are Flagella?

Long extensions that beat to propel motion effectively.

What are Hyphae?

Long microscopic tubes of mold.

Helminthes are eukaryotic animals: true or false?

True

Helminth cells have a cell wall: true or false?

False

Characteristics of Algae

Can be unicellular or multicellular, and are photosynthetic

What are bacterial cell walls composed of?

Peptidoglycan

Prokaryotes have a:

Nucleoid

What is a Virion?

An infectious viral particle.

Archaea cell walls are composed of peptidoglycan: true or false?

false

When is a human’s microbiota established?

During and directly after birth

List the 6 groups of microbes:

1. Fungi

2. Protozoa

3. Helminths

4. Algae

5. Bacteria/Archaea

6. Viruses

Carolus Linnaeus

Provided system for taxonomy (with only two kingdoms)

Robert Whitaker

Expanded the taxonomy for kingdoms: Animalia, Plantae, Fungi, Protista, and Prokaryotae

Carl Woese

Proposed additional taxonomic category of Domains: Eukarya, Bacteria, and Archaea

Taxonomic Organization:

(Domain), Kingdom, Phylum, Class, Order, Family, Genus, Species

What’s the purpose of using three domains for taxonomic categorization?

The domains are separated based on their rRNA sequences and characteristics

What is the template for binomial nomenclature?

Genus species

List the identifying characteristics of bacteria:

1. Physical characteristics

2. Biochemical tests

3. Serological tests

4. Phage typing

5. Genetic testing

Explain the Gram Stain procedure:

1. Primary stain/positively charged crystal violet

2. Iodine/mordant

3. Rinse with decolorizer

4. Secondary stain/positively charged safranin

How do negatively charged bacteria respond to the decolorizer during a gram stain?

The decolorizer breaks the outer membrane and the bacteria become colorless

Explain the Acid Fast Stain procedure:

1. Primary stain on slide warmer (Carbon Fuchsin)

2. Rinse

3. Decolorize and rinse

4. Secondary counterstain (Methylene Blue)

What color are Acid Fast Bacteria at the end of the procedure?

Fuchsia

What color are Non-Acid Fast Bacteria at the end of the procedure?

Methylene blue

Explain the Endospore Stain procedure:

1. Primary stain while on slide warmer (malachite green)

2. Wait and rinse

3. Secondary stain (safranin)

What color are Endospore bacteria the end of the procedure?

Red with green center

What color are vegetative bacteria following the endospore stain procedure?

Red

What two genera of bacteria produce endospores?

Bacillus and Clostridium

What two genera of bacteria respond to Acid Fast Stains?

Mycobacteria and Nocardia

Why do bacterial capsules not stain?

they are non-ionic (not charged)

Why can you not heat fix bacterial capsules?

Heat would destroy the capsule

Spirochete

Flexible spiral shape of Prokaryotic cells

Spirillum

Stiff spiral shape of Prokaryotic cells

Vibrio

Slightly curved rod shape of Prokaryotic cells

How do Prokaryotic cells reproduce?

Binary Fission

Binary Fission works similarly to mitosis: true or false?

true

What does the “strepto” prefix mean for Bacilli arrangements?

Chain

What are Fimbriae?

Small bristles that can stick to each other and surfaces, which can lead to biofilms.

What is the purpose of Pili?

For the transfer of DNA (bacterial conjugation)

S Layer

Single layer of proteins that bacteria can use for attachment

Glycocalyx

Sticky substance surrounding a bacterial cell composed of polysaccharides and/or polypeptides

What are the two forms of bacterial glycocalyx?

Slime Layer and Capsule

What is the difference between Slime Layer and Capsule?

Slime is loosely attached, capsule is tightly attached and protects from phagocytosis.

Biofilms resist antibiotic treatment: true or false

True

What in bacteria is composed of peptidoglycan?

Cell wall

Pick the true statement regarding Gram Positive Cell Envelopes

Thick layer of peptidoglycan

What contains the toxic compound known as LPS?

Gram Negative Cell Envelopes

Gram Positive Cell Envelopes have thin peptidoglycan, while Gram Negative have thick peptidoglycan: true or false?

False

Sporulation

The formation of an endospore (6-8 hours)

Germination

When an endospore becomes a bacterium again (1.5 hours)

Autotrophs

Use CO2 as carbon source

Heterotrophs

Obtain carbon in organic forms from other life forms

Phototrophs

Receive energy from sunlight

Chemotrophs

Obtain energy through the metabolizing of dead organisms

Neutrophile

pH requirement of 6.5-7.5

Acidophile

pH requirement of less than 6.5

Alkalinophile

pH requirement of greater than 7.5

What is a halophile?

An organism that grows in or tolerates saline conditions.

Obligate vs. Facultative

Requires vs. is able to

What two molecules can be disrupted due to temperature changes?

Proteins and lipids (lipid membranes)

Psychrophiles prefer

below 15° C

Mesophiles prefer

20-40° C

Thermophiles prefer

45-80° C

Hyperthermophiles prefer

above 85° C

What is generation time?

The time required for a population of cells to double.

Name and describe the four phases of Microbial Growth:

1. Lag Phase (no growth)

2. Exponential (grows exponentially)

3. Stationary (dying=produced)

4. Death (too much waste, low nutrients)

Viable plate counts involve exponential percentage dilution of a cultured broth: true or false?

True

Aerobes

require oxygen

Anaerobes

do not require oxygen

Aerotolerant Anaerobes

are not aerobic, but have enzymes that detoxify poisonous oxygen

Microaeophiles

require 2-10% oxygen

What three forms of oxygen are reactive?

• Superoxide ion O₂-

• Hydrogen peroxide H₂O₂

• Hydroxyl OH-

What do cells use to neutralize reactive oxygen?

• Catalase

• Superoxide dismutase

What are the “Five I’s”?

1. Inoculation

2. Incubation

3. Isolation

4. Inspection

5. Identification

What are the three ways to classify media?

1. Physical state

2. Chemical composition

3. Functional type

What is Defined/Synthetic Media?

Media for culturing microbes where the exact chemical composition is known.

What is Selective Media?

Media for culturing microbes that favors or inhibits the growth of particular microbes

What is Differential Media?

Media for culturing microbes that reveals distinct visual characteristics between species.