HLSC 128 Microbiology

What are the two types of prokaryotes?

1. Eu-bacteria/”True bacteria”

   • Group that causes disease

   • Local environment

2. Archaebacteria/”Ancient bacteria”

   • Don’t cause disease

   • Isolated and extreme environment

What are the four types of eukaryotes?

1. Fungi

2. Protozoa

3. Multicellular animal parasites

4. Algae

Who made the quote: “Life only comes from life”?

Louie Pasteur

Describe the experiments Louie Pasteur had done to determine that life did not arise spontaneously from nonliving matter.

In his trials, he had heated flasks filled with broth with air and removed air (open and closed), and found that the broth was infested when the flask was open with air. He then heated the neck of the flask into an S-shape and left the flask open for air. Pasteur found that the broth was not present with microbes as they had gotten suck in the bends.

What is pasteurization?

It is a heating process to remove the bacteria from food and beverages. The purpose is to make them safe for consumption and extend shelf life.

What is fermentation?

It is the metabolic process of bacteria and yeast where they convert sugars into alcohol.

Who is the scientist that discovered the bacterium that causes anthrax?

Robert Koch

What are the Koch’s Postulates?

Experimental steps to prove that a specific microbe causes a specific disease.

What was Edward Jenner known for?

Edward Jenner was known for creating the first vaccine. In his time smallpox was a epidemic. He inoculated a subject with cowpox virus (fluid from a blister) and found that the subject had complete immunity from smallpox.

What are the building blocks of proteins called?

Amino acids

What are the four structures of a protein?

1. Primary structure

• Polypeptide chain

2. Secondary structure

• Helical shape made of a-helix sheets

3. Tertiary structure

• Pleated structure made up of beta sheets

4. Quaternary structure

• 3D mix of a-helix and b-sheets

What prime carbon does ribose lose oxygen from?

2’

What are the five prokaryote shapes?

1. Spiral

2. Bacillus

3. Coccus

4. Coccobacillus

5. Pleomorphic

What shape is this? Describe it.

Spiral Vibrio, it is tender

What shape is this? Describe it.

Spiral Spirillum, it is rigid and moves by means of flagella

What shape is this? Describe it.

Spiral Spirochete, it flexible and moves by means of appendages called axial filaments which curve around its structure

What shape is this?

It is a single bacillus

What shape is this?

It is a diplobacilli

What shape is this?

It is a streptobacilli

What shape is this? Describe it.

It is a diplococci. Produced when cocci divide and remain attached to eachother.

What shape is this? Describe it.

It is a streptococci. If cocci divides and forms a chain-like structure.

What shape is this? Describe it.

It is a staphylococci. Happens when cocci divide and bunch together into a grape-like structure

What does the glycocalyx do for a prokaryote?

• Increases virulence

  • By its sugar sticky nature

• Evades phagocytosis

Describe the structure of a flagella in a prokaryote.

1. Made up of filaments which are made up of flagellin

2. Attached to a rotating protein hook

3. Anchored to the cell wall and plasma membrane by the basal body (two set of rings)

What are the four types of flagellum?

1. Monotrichous (singular/whip)

2. Amphitrichous (double sided whip)

3. Lophotrichous (bundle on one side)

4. Petrichous (arrangement is all around the cell)

What does it mean when flagella like to “run”?

This means that flagella keep moving and moving till they hit a barrier, where they tumble and change direction. They regain themselves from tumbling and start moving again to another direction repeating the tumbling motion against barriers.

Describe axial filaments/endoflagella.

• Found in spirochetes

• Anchored at one end of a cell

• Rotate and wrap around cell with powerful spiral movements

What are pili?

Projections that connect from one cell to another to facilitate DNA transfer

What are fimbriae?

They are tiny projections from outside a cell’s surface, being shorter and thinner than flagella

Describe the “peptido” portion of Peptidoglycan.

Polypeptide that connects the sugar backbone by peptide bonds with side-chains and cross-bridge amino acids

Describe the “glycan” portion of Peptidoglycan.

• It is a polymer of glucose

• Makes up sugar backbone that is NAM and NAG which form a wall

Describe a Gram-positive cell wall.

• Contains several thick layers of peptidoglycan

• Contain Teichoic acids

Describe Teichoic acids.

• Mix of alcohol and phosphate

• Two types

1. Ribityl (5 carbons)

2. Glycerol (3 carbons)

• If remaining in wall they are called Lipoteichoic acids

• Provide antigen specific nature and attract positive ions

Describe a Gram-negative cell wall. 

• Outer membrane

  • Contains lipoproteins, porin protein channels, and lipopolysaccharides

  • Lipopolysaccharide is an endotoxin, which contains Lipid A that when released causes inflammatory response

• Thin layer of peptidoglycan

• Periplasmic space

What is an Acid-fast cell wall?

It is a waxy lipid later bound to PG that is made up of Mycolic acid

What is a mycoplasma’s cell wall?

No cell wall and only plasma membrane with sterols present

What is an archaea’s cell wall?

Archaea do not have cell walls, and the rare case they do is pseudo PG (false PG)

What does lysozyme digest when damaging peptidoglycan?

It digests the disaccharide, the backbone of glycan.

When a lyzosome digests the disaccharide in peptidoglycan, A Gram-positive devoid of cell wall is called a _______, while a gram-negative devoid of cell wall is called a _____

“protoplast”, “spheroplast”

Ribosome: ___S +__S = Complete 70S ribosome

30S + 50S

How is a holoenzyme (whole enzyme) made?

Inactive Apoenzyme (protein portion) + Cofactor activator (nonprotein portion)

Describe coenzymes. Give two examples.

A type of cofactor is a coenzyme

• Accept/donate electrons from substrate

• Act as electron carriers

• e.g. NADP and FAD

What do enzymes do?

• Act as biological catalysts

  • Lower activation energy

  • Active site is specific in nature

  • Unharmed in reaction—reused

What does penicillin do to peptidoglycan?

It inhibits the peptide brides that connect the backbone

Describe endospores.

Resting cells formed by Bacillus, Clostridium species (Gram+)

• Resistant to desiccation, heat and chemicals

What does Clostridium Tetani cause?

Tetanus

What does Clostridium Botulinum cause?

Botulism

What does Clostridium Perfringens cause?

Gangrene

What does Clostridium Difficile cause?

Colitis

What is the exception to Gram negative species with endospore?

Coxiella Burneti which causes ammonia called Q-fever

How is endospore formed, and what returns to their vegetative state?

Sporulation, germination

How many membranes does an endospore have?

Two

Endospore contains DPA, what does it do?

Gives it resistance to endure time of rest and it is only found in endospores.

What is a basic dye?

A salt in which the color is in the positive ion

What is an acidic dye?

A salt in which the color is in the negative ion—used for negative staining

Describe capsule staining.

1. Mix bacteria in a solution containing India ink or nigrosin to provide a contrasting background and stain cells with simple stain

2. Shows up as light areas surrounding stained cells

Describe endospore staining

1. Malachite green dye cannot penetrate the endospore wall itself, so heat is applied to penetrate it.

2. It is washed with water to remove green dye from cell parts except endospores

3. Counterstain: Safranin is applied to stain portions of cell other than endospores

4. Endospores should appear green within a red/pink cell

Describe flagella staining

1. Carbol fuchsin to stain

2. Mordant: Potassium alum to enlarge and build up diamters of flagella

Flagella is a very tiny structure and is prone to breaking apart and floating away

What is negative staining?

A procedure that results in colorless bacteria against a stained background

What is a simple stain?

Staining microbes with a single basic dye, a mordant may be added to intensify stain

What are functions of a mordant?

• Increase affinity of a stain

• Coat structure to make it easier to see

Describe a Gram-stain procedure.

Staining a gram positive and a gram negative

1. Primary stain: Crystal violet basic dye that imparts a purple color to both cells

2. An iodine mordant is added, both cells appear dark violet

3. Decolorizing agent: Removes stain from some specie cells with an alcohol-acetone solution

4. Counterstain: Stained with safranin (basic red dye)

• Gram+ retain original purple stain

• Gram- lose purple stain and take on a pink color (counterstain)

Describe an Acid-fast stain procedure.

Only binds to bacteria with waxy material in their cell walls

• e.g. Mycobacterium species: Detecting tuberculosis and leprosy

1. Primary stain: red dye Carbolfuchsin, and heated to enhance penetration and retention of dye

2. Decolourizing agent: Acid-alcohol, removes red stain from bacteria that are not acid-fast as they lack lipid components

3. Counterstain: Methylene blue

• Red are tuberculosis acid-fast Gram+ cells

• Blue are non-acid-fast cells