Lecture 1 - Micro overview

Question 1

Microbial disease results from complex dance between?

Answer 1

Complex dance between multiple microbial virulence factors and host resistance factors

Question 2

Pathogens are organisms with unique, genetically endowed capacities to:

Answer 2

1. Colonize the host
2. overcome host immunity
3. Replicate within the host environment and/or cause host tissue damage

Question 3

What are virulence factors?

Answer 3

Molecule or activities that permit Pathogens to colonize host, overcome host immunity and replicate within the host environment and cause host tissue damage

Question 4

Name 5 virulence factors:

Answer 4

Adherence factors
toxins
Inflammatory mediators, 
Anti-host enzymes
Bacterial capsules

Question 5

Opportunistic flora are what:

Answer 5

non-pathogenic normal flora that cause disease only under abnormal host conditions such as decreased competition from other microbes

Question 6

Prokaryotic cells include ?

Answer 6

all bacteria

Archaea

Question 7

Relationship between life forms is measured by?

Answer 7

Genetic similarity

Question 8

Name the major infectious agents:

Answer 8

Eukaryotes (Fungus, protozoa, helminths)
Prokaryotes (Bacteria and archaea)
Viruses
Prions

Question 9

T or F, Bacteria are prokaryotic cells. As such they contain membrane-bound organelles.

Answer 9

False, They contain NO membrane-bound organelles

Question 10

Bacterial genetic material is:

Answer 10

contained in one, circular dsDNA molecule

Question 11

How are bacterial ribosomes different than humans?

Answer 11

Bacterial are 70s ribosomes
Humans 80 s ribosomes
- 70s ribosome are a target for some antibiotics

Question 12

Bacteria have what type of cell membrane?

Answer 12

A regular bi-lipid cell membrane around which is a rigid cell wall (another target for some antibiotics)

Question 13

Name some of the surface molecules found in the cell membrane of bacteria

Answer 13

1. Pili (fimbrae) used for attachment and conjugation
2. Flagella used for locomotion
3. Capsule used to protect from phagocytosis
4. LPS a major virulence factor, found in th eouter membrane of G- bacteria

Question 14

T or F, Bacteria typically live in complex ecological biosystems termed biofilms

Answer 14

True

Question 15

Describe G+ cell walls

Answer 15

Thick cell walls and a single inner plasma membrane

Question 16

Describe G- cell walls

Answer 16

Thin cell wall that is betewen the cell membrane and a unique outer membrane

Question 17

T or F, Capsules often do not have anti-phagocytic properties

Answer 17

False, They often have strong anti-phagocytic properties

Question 18

T or F, The bacterial cell wall is an essential, all enclosing, rigid, porous, protective-girdle that surrounds the bacterial cell.

Answer 18

True

Question 19

What does the cell wall protect the cell from?

Answer 19

It protects the plasma membrane from osmotic pressure

Question 20

Cell wall is a ridged mesh of ropelike, linear, polysaccahride chains cross-linked by peptides. What forms the polysaccharide chains?

Answer 20

Repeating, modified glucose-dimers called N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM)

Question 21

What is the membrane-bound enzyme that spot-welds the polysaccharide “girders” into place by cross-linking the peptides hanging from the girders to peptides dangling from the existing wall?

Answer 21

transpeptidases

Question 22

T or f, Peptidoglycan is constantly being synthesized and degraded by proteases

Answer 22

False, by autolysins

Question 23

The outer leaflet of the outer membrane of G- bacteria contains a toxic lipopolysaccharide termed:

Answer 23

Endotoxin (LPS)

Question 24

In small amounts LPS is excellent at what:

What happens at large amounts?

Answer 24

activating the innate immune reaction
Large amounts: especially systemically, LPS can cause very serious problems like activating clotting system, leading to disseminated intravascular coagulation which can obstruct blood flow.

Question 25

LPS in certain amounts can activate what two things?

Answer 25

Clotting system

Macrophage activity

Question 26

What is activated in response to Macrophage activation by LPS

Answer 26

1. TNF-alpha - signals endothelial cells to produce NO which causes pre-capillary sphincters to relax, decreases BP and may cause hypovolemic shock
2. PGE2 may be activated and in turn activate osteoclasts to resorb bone
3. Proteases - breakdown extracellular matrix in the area

Question 27

In nature, large glucose polysaccharides form very useful molecules that generally serve two major functions:

Answer 27

1. Structural (Cellulose, Chitin, ECM, Peptidoglycan)

2. Food storage (Starch, Glycogen)

Question 28

Strep mutans secrete dextran. Dextran have what core bonds?

Answer 28

Alpha 1-3 bonds with alpha 1-6 branches

Question 29

T or F, Some bacteria have heme proteins

Answer 29

True

Question 30

Bacteria with heme proteins are able to do what?

Answer 30

THey are capable of respiration - turning sugars and oxygen into CO2 and water (our mitochondria do this)

Question 31

What do facultative bacteria require

Answer 31

They can respire if oxygen is present but can survive on fermentation if oxygen is absent
- Gaining energy by partially breaking down substrate to other organic molecules like lactic acid or alcohol

Question 32

What does SOD do?

Answer 32

Produces the less toxic, hydrogen peroxide from the very toxic, O2-

Question 33

What does Catalase do?

Answer 33

further converts H2O2 to water and oxygen