3. Prokaryotic Structure and Function, H. pylori

Question 1

G+ (only) bacterial cell walls contain large amounts of ___________

Answer 1

Teichoic acids

Question 2

Teichoic acids are polymers of ______ or _____ joined by ___________

Answer 2

Polymers of glycerol or ribitol joined by phosphate esters

Question 3

Difference between teichoic and lipoteichoic acid?

Answer 3

Lipoteichoic acids go thorugh peptidoglycan are anchored to the PM, teichoic is only connected to peptidoglycan

Question 4

G+ bacterial walls are _______ charged due to the presence of_____________

Answer 4

negatively; teichoic acids

Question 5

Compared to G+ bacteria, G- bacteria have an additional ________________

Answer 5

outer membrane

Question 6

Structure of G- outer membrane?

Answer 6

Bilayer outside peptidoglycan layer

Question 7

4 functions of G- outer membrane?

Answer 7

Selective permeability

Immunogenic

Confer negative charge

Protect bacteria from toxins and enzymes (since peptidoglycan is thin)

Question 8

Porin proteins of G- envelope are selectively permeable to molecules _______ 600 Daltons

Answer 8

Less than or equal to

Question 9

O-specific side chains are polysaccharides of _________ and they can stimulate ________

Answer 9

lipopolysaccharides (LPS)

immune response

Question 10

3 components that make up the basic structure of LPS?

Answer 10

Lipid A, core polysaccharide, O-side chain

Question 11

Most abundant protein in outer membrane? Function?

Answer 11

Braun’s lipoprotein

Links outer membrane to peptidoglycan

Question 12

Koch’s postulate?

Answer 12

1. Must be present in every case of the disease
2. Must be isolated and grown in pure culture
3. Same disease must result when isolated microbe is inoculated into a healthy host
4. Same microbe must be isolated again from diseased host

Question 13

2 scientists who received Nobel for linking H.pylori with gatritis (fulfilled Koch’s postulates)

Answer 13

Marshall and Warren

Question 14

What was H.pylori initially named? Reason?

Answer 14

Campylobacter pyloridis

Located near pyloric sphincter and resembled bacteria in genus Campylobacter

Question 15

Location of LPS?

Answer 15

On OUTER LEAFLET of the membrane (don’t just write outer membrane)

Question 16

Recent studies on H.pylori found that it causes an __X increase risk in gastric cancer

Answer 16

8X

Question 17

Only bacterium classified as a carcinogen by WHO?

Answer 17

H. pylori

Question 18

Who intentionally exposed himself to H. pylori?

Answer 18

Barry Marshall

Question 19

3 points of INDIRECT evidence supporting H.pylori causing gastritis

Answer 19

Location - exists at sites of gastritis

Age distribution - more H. pylori found in older population and incidence of gastritis higher in elderly

Epidemiology - 1980’s survey of patients who had a gastric biopsy showed link between evidence of gastritis in tissue and recovery of H.pylori

Question 20

H. pylori is a ______ shaped bacterium

Answer 20

spiral

Question 21

Proteins that allow H.pylori to bind to host epithelium?

Answer 21

adhesins

Question 22

H.pylori G+ or G-?

Answer 22

G-

Question 23

H.pylori prefer low O2 concentrations and so they are known as ___________

Answer 23

microaerophilic

Prefer O2 conc of 2-10% (stomach)

Question 24

2 enzymes secreted by H.pylori? Functions?

Answer 24

Mucinase - hydrolyzes viscous mucin

Urease - cleaves urea to CO2+NH3 to make its own alkaline cloud

Question 25

Protein toxin secreted by H.pylori? Function?

Answer 25

VacA - causes epithelial pores to form so that nutrients leak out

Question 26

Bacterial disease-causing protein injected into host cells by H.pylori? Function?

Answer 26

CagA - makes cells leaky to further aid disease process

Question 27

Word origin of teichoic acids?

Answer 27

Greek - teichos = wall

Question 28

Teichoic acids are sometimes bound to _________

Answer 28

amino acids (+lipids)

Question 29

Unique structure of G+ bacteria? Of G- bacteria?

Answer 29

G+ = teichoic acids

G- = outer membrane

Question 30

By convention, the outer membrane of G- bacteria actually contains both of _______________ and _____________

Answer 30

outer membrane and inner membrane

Question 31

Where is peptidoglycan located in G- bacteria?

Answer 31

In the periplasmic space

Question 32

What confers negative charge to G+/G- bacteria?

Answer 32

G+ = teichoic acids

G- = outer membrane

Question 33

4 things found on/in outer membrane of G- bacteria?

Answer 33

Porins, LPS, O-specific side chains, Braun’s lipoprotein

Question 34

Full name of H. pylori?

Answer 34

Helicobacter pylori

Question 35

How do H. pylori obtain nutrients?

Answer 35

Secrete VacA/CagA