Lecture 1: Bacterial Morphology and Structure 1

Question 1

What are the two most common shapes of bacteria

Answer 1

1. Coccus- sphere/round
2. Bacillus- rod

Question 2

What are 4 other common shapes of bacteria

Answer 2

1. Coccobacillus- short rod
2. Vibrio- comma shape
3. Spirochete- flexible, thin spiral-shaped rod
4. Spirillum- rigid, spiral-shaped rod

Question 3

What does it mean if a bacteria is pleomorphic

Answer 3

Has no defined shape, variety of shapes in one species

Question 4

Identify bacteria shapes 1-6

Answer 4

1. Coccus
2. Bacillus
3. Coccobacillus
4. Vibrio
5. Spirillium
6. Spirochete

Question 5

What is the prefix of bacteria that divides in one plan in a pair

Answer 5

Diplo

Question 6

What is the prefix of bacteria that divides in one plain in a chain

Answer 6

Strepto

Question 7

What is the prefix of a bacteria that divides in 2 planes in a grape like cluster

Answer 7

Staphylo

Question 8

What is the prefix of a bacteria that divides in 2 planes in a packet of 4 cells

Answer 8

Tetrads

Question 9

What is the prefix of a bacteria that divides in 2 planes in packets of 8 cells

Answer 9

Sarcina

Question 10

Identify bacteria based on arrangement and shape

Answer 10

Diplococcus

Question 11

Identify the bacteria based on arrangement and shape

Answer 11

Streptococcus

Question 12

what is the arrangement of this bacteria

Answer 12

Staphylo

Question 13

What is the arrangement of this bacteria

Answer 13

Tetrad

Question 14

What is the arrangement of this bacteria

Answer 14

Sarcina

Question 15

What are the functions of the bacterial cytoplasmic membrane

Answer 15

Permeability and transport, site of electron transport chain, excrete toxins, chemotaxis

Question 16

What are 2 examples of bacteria genera without cell walls

Answer 16

1. Mycoplasma
2. Ureaplasma

Question 17

What are the three main types of cell walls

Answer 17

1. Gram negative
2. Gram positive
3. Acid fast

Question 18

In order from left to right identify the types of bacterial cell walls

Answer 18

left: gram negative
Middle: gram positive
Right: acid fast

Question 19

What are the 2 main components all three cell walls have

Answer 19

1. Peptidoglycan
2. lipoproteins

Question 20

What is the function of peptidoglycan and lipoproteins

Answer 20

Structural support

Question 21

What 3 parts make up the peptidoglycan layer

Answer 21

1. Backbone: NAG-NAM segments
2. Set of tetrapeptide chains
3. Set of peptide cross bridges

Question 22

Why is peptidoglycan clinically relevant when treating a bacterial infection

Answer 22

Can target peptidoglycan layer as it is crucial to cell support, damage it and cell wall loses integrity and can lyse

Question 23

What enzyme is found in secretions and can weaken the cell integrity by damaging peptidoglycan layer

Answer 23

Lysozymes

Question 24

Gram positive or gram negative: thick peptidoglycan layer

Answer 24

Gram positive

Question 25

What color does gram positive bacteria stain

Answer 25

Purple

Question 26

Gram positive or gram negative: thin peptidoglycan layer

Answer 26

Gram negative

Question 27

What color does gram negative bacteria stain

Answer 27

Red

Question 28

What is the primary stain in a gram stain

Answer 28

Crystal violet

Question 29

What is the counter stain in gram stains

Answer 29

Safranin (red)

Question 30

What is the periplasmic space and is it typical of gram positive or negative

Answer 30

Found in gram negative Space between inner and outer membranes

Question 31

What does periplasmic space contain

Answer 31

1. Thin peptidoglycan layer 2. Binding proteins 3. Transport proteins 4. Hydrolytic enzymes

Question 32

What is the outer membrane and is it specific to gram negative or positive

Answer 32

Specific to gram negative Bilayered structure: inner layer: resembles cytoplasmic membrane, outer membrane: contains phospholipids and LPS

Question 33

What is the distinct component on the outer membrane of a gram negative bacteria

Answer 33

LPS

Question 34

What is the function of the outer membrane

Answer 34

Protective permeability barrier to large molecules and hydrophobic molecules, impedes phagocytic destruction

Question 35

What are the 3 components of LPS

Answer 35

1. O-antigen 2. Core polysaccharide 3. Lipid A

Question 36

What is/ what is the function the O- antigen

Answer 36

Outermost portion of LPS, serves as attachment sites, inhibits phagocytosis, can identify strains

Question 37

What is/the function of the core polysaccharide

Answer 37

Attaches O-Antigen to Lipid A

Question 38

What is/the function of Lipid A

Answer 38

Virulence factor/toxin of LPS—> endotoxin that produces cytokines and inflammatory mediators that can lead to endotoxic shock

Question 39

Which component of the LPS is responsible for endotoxic shock

Answer 39

Lipid A

Question 40

Why are endotoxins clinically relevant in horses

Answer 40

Leading cause of equine death—> major part of GI disorders like colic and neonatal foal septicemia

Question 41

Why are endotoxins clinically relevant in cattle

Answer 41

Play significant role in laminitis and abomasal displacement

Question 42

Which bacterial cell wall has trimeric porins

Answer 42

Gram negative

Question 43

What is the function of a porin

Answer 43

Transport of solutes

Question 44

What are the two components only found in gram positive bacteria

Answer 44

1. Teichoic acid (WTA) 2. Lipoteichoic acid (LTA)

Question 45

Where is teichoic acid anchored to

Answer 45

Peptidoglycan

Question 46

Where is lipoteichoic acid anchored to

Answer 46

Cell membrane

Question 47

What is the function of teichoic and lipoteichoic acid

Answer 47

Adherence to cell host, serves as a virulence factor and can initiate endotoxin like behavior

Question 48

Gram negative or gram positive: release endotoxins

Answer 48

Gram negative (gram positive can have endotoxin like effects but has no LPS so not endotoxin)

Question 49

What structure is specific to outer layer of acid fast bacteria cell walls

Answer 49

Mycolic acid layer

Question 50

What does the mycolic acid layer consist of

Answer 50

Long fatty acid chains and lipids that give waxy coat

Question 51

How are mycolic acids connected to peptidoglycan layer

Answer 51

Via arabinogalactan

Question 52

What is the function of mycolic acid layer

Answer 52

Provides resistance to dessiccation and some antibiotics, inhibits phagocytosis

Question 53

What bacterial cell wall has tetrameric porins

Answer 53

Acids fast bacteria

Question 54

What are two clinically relevant genera that are acid fast

Answer 54

1. Mycobacterium 2. Nocardia

Question 55

What is the primary stain in acid fast

Answer 55

Carbolfuschin (acid fast-red)

Question 56

What is the counter stain in acid fast

Answer 56

Methylene blue (nonacid-blue)

Question 57

What are the steps in acid fast staining

Answer 57

1. Primary stain-carbolfuschin (acid fast-red) 2. Heat 3. Acid-alcohol wash-depolarization 4. Counterstain- methylene blue (non-acid fast)

Question 58

In this acid fast stain, what is A and B, and which one is acid fast bacteria

Answer 58

A. Staphylococcus (grape like clusters, round) B. Mycobacterium- acid fast- red

Question 59

A stained tracheal mucus specimen collected from a cattle shows acid fast bacilli. Which of the following genera should be included in your differential diagnosis: A. Clostridium B. Bacillus C. Staphylococcus D. Mycobacterium

Answer 59

D. Mycobacterium

Question 60

A foal was diagnosed with endotoxemia caused by endotoxins released into bloodstream. The bacterial cell wall structure causing the patients symptom is which of the following: A. Lipid A B. O antigen C. Teichoic acid D. Lipoprotein

Answer 60

A. Lipid A

Question 61

Gram negative or positive: sensitive to penicillin

Answer 61

Gram positive more susceptible

Question 62

Gram negative or positive: sensitivity to lysozymes

Answer 62

Gram positive yes