Introduction to Bacteriology

Question 1

Which archaea are pathogenic?

Answer 1

None

Question 2

What distinguishes prokaryotes from eukaryotes?

Answer 2

A nuclear membrane

Question 3

What are bacterial capsules (glycocalyx) usually made of, what do they do and what else are they called?

Answer 3

Usually made of polysaccharide (may be proteinaceous), help bacteria survive in host (aka virulence factors)

Question 4

What do bacterial fimbria do?

Answer 4

Help colonize host by aiding in attachment

Question 5

What do bacterial pili do?

Answer 5

Aid in genetic exchange

Question 6

What makes prokaryotic ribosomes different from eukaryotic ribosomes?

Answer 6

They are smaller (70S, containing 50S and 30S subunits) than eukaryotic ones (80S)

Question 7

What staining method is used to visualize mycobacteria?

Answer 7

Acid-fast staining

Question 8

What are the terms for bacteria with a spherical shape and rod-like shape respectively?

Answer 8

Coccus (e.g. streptococcus) and bacillus (e.g. escherichia coli)

Question 9

What are the terms for S shaped bacteria shorter than one sine wave and longer than one sine wave respectively

Answer 9

Shorter - spirillum (e.g. helicobacter), longer - spirochetes (e.g. borrelia)

Question 10

4 types of flagellar arrangements on bacteria

Answer 10

Monotrichous (single, polar), Amphitrichous (a tuft at each end), Lophotrichous (one or more at each pole), Peritrichous (distributed over entire surface)

Question 11

What type of organisms does acid fast stain stain for?

Answer 11

Those with high lipid content (often used with hard to stain organisms)

Question 12

What does India Ink stain for?

Answer 12

It is a negative stain for capsules

Question 13

Sporulation

Answer 13

Reversible differentiation in response to conditions. Conversion to dormant state when nutrient depleted. Done by some gram-positive bacteria, esp Bacillus and Clostridium genera

Question 14

Three basic parts of a flagellum

Answer 14

Filament (made of flagellin), Hook, Basal body

Question 15

What is another name for flagellar protein and why is it called this?

Answer 15

H antigen. It is highly antigenic and useful for distinguishing different Gram-negative baceteria

Question 16

Axial filaments (endoflagella)

Answer 16

Bundles of filaments similar to flagella but under a sheath. Used by spirochetes

Question 17

What about their composition differentiates prokaryotic PMs from eukaryotic PMs?

Answer 17

Prokaryotic plasma membranes contain no sterols, they are much more fluid as a result

Question 18

What is the major component of bacterial cell walls, what other organisms is it found in, and what is it composed of?

Answer 18

Peptidoglycan. Unique to bacteria. Comprise of N-acetyl glucosamine (NAG) and N-acetyl muramic acid (NAM)

Question 19

What type of bond joins NAM and NAG in bacterial walls?

Answer 19

B1-4 glycosidic bond

Question 20

What is the difference in the composition of cell wall between gram-negative and gram-positive?

Answer 20

Gram-negative contain diamino pimelic acid (DAP), gram-positive contain diamino AA lysine instead of DAP

Question 21

What type of bacteria have a peptide bridge in their cell walls?

Answer 21

Gram-positive bacteria have a variable length peptide bridge in their cell walls (gram negative have direct peptide bonds linking peptidoglycan)

Question 22

What type of bacteria have extensively cross-linked cell walls?

Answer 22

Gram-positive bacteria. Gram-negative cells have a thin layer of peptidoglycan, while gram-positives have multiple cross-linked layers

Question 23

What bacterial function do vancomycin, penicillins, and bacitracin inhibit?

Answer 23

Cell wall (peptidoglycan) synthesis. Vancomycin (binds terminal alanine) and penicillins (inhibits PBPs that remove terminal alanine) prevent cross-linkage, bacitracin blocks dephosphorylation of bactoprenol-PP

Question 24

What type of bacteria have teichoic acids in their cell wall and what is the sigificance of these molecules?

Answer 24

Gram-positive bacteria. Teichoic acis and lipoteichoic acids are major antigenic determinants

Question 25

Three major components of LPS

Answer 25

Lipid A (two NAG phosphates linked to branched FAs), Core polysaccharides (similar within a given species), O-specific polysaccharides (highly variable, antigenic specificity)

Question 26

What is periplasm and what type of bacteria have periplasm?

Answer 26

Gram-negative organisms, it is a space between cell wall and outer membrane

Question 27

What is the order from outermost to innermost in bacteria: cell wall, capsule, plasma membrane

Answer 27

Capsule, cell wall, plasma membrane

Question 28

What is an outer membrane and what kind of bacteria have it?

Answer 28

An extra membrane outside the cell wall, serves as a barrier to hydrophobic compounds and attaches to host cells, possessed by gram-negative bacteria