Lecture 14

Question 1

Barriers to Infection

Answer 1

1. Physical Barriers
2. Chemical Barriers

Question 2

Physical Barriers

Answer 2

Epithelial Layers:
1. Skin
2. Mucosa
3. Glands

Question 3

Chemical Barriers

Answer 3

1. Acidic pH
2. Antimicrobial Agents

Question 4

Additional Barriers

Answer 4

1. Glycocalyx
2. Mucus

Question 5

Epidermis

Answer 5

1. Stratified epithelium
2. Keratinized Layer

Question 6

Mucosa

Answer 6

1. Epithelial cells make mucus
2. Phage bind to sugars in the mucus
3. Protective layer is established
4. Phage can infect and destroy/ susceptible bacteria

Question 7

A. Phage

Answer 7

Consistently found in mucus across species

Question 8

B. Phage

Answer 8

Display a modest binding affinity for mucus glycoproteins

Question 9

Epithelial Secretions

Answer 9

Controlling surface microbe populations

Question 10

Proteolytic Enzymes

Answer 10

Lysozyme

Question 11

Lysozyme

Answer 11

1. Secreted into tears, saliva, milk, respiratory tract
2. Cleaves peptidoglycan molecules in bacterial cell walls

Question 12

Gram Negative Bacteria: Less sensitive

Answer 12

E. coli
1. Cell wall organization
2. LPS
3. Outer membrane
4. Peptidoglycan
5. Inner membrane

Question 13

Gram Positive Bacteria: More sensitive

Answer 13

S. areus
1. Glycolipids
2. Glycoproteins
3. Peptidoglycan
4. Membrane

Question 14

Lysozome Effects on Bacteria

Answer 14

1. Loss of structural support of the plasma membrane
2. More susceptible to osmotic stresses
3. Loss of physical barrier

Question 15

Metal Ion Chelators

Answer 15

1. Lactoferrin (Fe3+)
2. Calprotectin (Ca2+)
3. Psoriasin (Ca2+)

Question 16

Psoriasin Prevents E. coli Colonization

Answer 16

Skin secretes psoriasin (Ca2+ chelation)

Question 17

Antimicrobial Peptides

Answer 17

1. a-defensin
2. b- defensin
3. cathelicidin

Question 18

Antimicrobial Peptides

Answer 18

1. Cationic
2. Amphipathic

Question 19

Defensins

Answer 19

Forms pores in bacterial membranes

Question 20

A. Epithelia

Answer 20

Constitutive secretion

Question 21

Neutrophils

Answer 21

Secretory granules

Question 22

Infected Tissues

Answer 22

Induced expression

Question 23

a-defensin: Small Intestinal Paneth Cells

Answer 23

1. Defend from pathogens
2. Shape microbiota
3. Protect stem cells

Question 24

PRR Receptors that trigger Phagocytosis

Answer 24

1. C-type lectin receptors
2. Scavenger receptors

Question 24

Opsonin Receptors that trigger Phagocytosis

Answer 24

1. Collagen-domain receptors 2. Complement receptors 3. Immunoglobulin Fc receptors

Question 25

Five Steps in Phagocytosis: Step 1

Answer 25

Bacterium becomes attached to membrane evaginations called pseudopodia

Question 26

Five Steps in Phagocytosis: Step 2

Answer 26

Bacterium is ingested, forming phagosome

Question 27

Five Steps in Phagocytosis: Step 3

Answer 27

Phagosome fuse with lysosome

Question 28

Five Steps in Phagocytosis: Step 4

Answer 28

Bacterium is killed and then digested by lysosomal enzymes

Question 29

Five Steps in Phagocytosis: Step 5

Answer 29

Digestion products are released from cell

Question 30

Lysosomal Degradation

Answer 30

1. Antimicrobial peptides - defensins - cathelicidins 2. Reactive Oxygen Species 3. low pH 4. Acid-activated dig. enzymes