Helicobacter Pylori

Question 1

What causes gastric ulceration

Answer 1

Helicobacter pylori

Question 2

What type of bacterium is H.pylori

Answer 2

Gram negative

Question 3

What separates 2 lipid bilayers

Answer 3

Periplasm

Question 4

Where is the urease enzyme

Answer 4

Cytosol of the bacterium

Question 5

Function of urease enzyme

Answer 5

Catalyses the conversion of urea to ammonia (base)

Question 6

Test strip contain ____ zones

Answer 6

4

Question 7

What are the zones in test strip

Answer 7

Reaction zone
Test zone
Control zone
Absorbent pad

Question 8

Function of absorbent pad

Answer 8

Where excess sample is collected

Question 9

A negative result on test strip

Answer 9

C T
I III III I
Neg = result on control zone

Question 10

A positive result

Answer 10

C T
I III III III I
Pos = result on control + test zone

Question 11

An invalid result

Answer 11

C T R
I III III I
I III I
Both test zone has a result or there is no result

Question 12

Urease enzyme contain __ different amino acid chains

Answer 12

2

• alpha = 238 amino acids
• beta = 569 amino acids

Question 13

Functional urease enzyme has __ ab3 modules, __ amino __ amino acid chains + __ catalytic units

Answer 13

4 ab3 modules
24 amino acid chains
12 catalytic units

Question 14

What is the mw of urease enzyme

Answer 14

> 1million g/mol

Question 15

What is the cofactor in the urease enzyme

Answer 15

Ni2+ ions per beta chain (metalloenzyme)

Question 16

Non-invasive tests

Answer 16

Blood,
Breath
Stool

Question 17

Invasive tests

Answer 17

Gastroscopy /biopsy for culture

Question 18

Where is the control zone

Answer 18

Furthest away from reaction zone

Question 19

How do you know if the strip test is invalid

Answer 19

If the control zone does not produce a line

Question 20

A positive result of the stool antigen (strip) test confirms…

Answer 20

Patient has Helicobacter pylori

Question 21

Antigen strip test

Answer 21

Based on the detection of antigens in the patient sample by antibodies

Question 22

CLO test

Answer 22

(Campylobacter-like organism test) Quick test carried out during gastroscopy (looking at lower end of oesophagus, stomach + upper part of duodenum)
Based on the ability of Helicobacter urease enzyme

Question 23

Requirements of colonisation of the stomach

Answer 23

MAAD

• Movement towards epithelial cells: flagella
• Acid-neutralising system: urease enzyme; transporter proteins
• Adhesins present on outer membrane
• Degradative enzymes + proteases (of mucus proteins): move through mucus layer

Question 24

What are the consequences of stomach colonisation of Helicobacter pylori

Answer 24

Mucus layer is damaged therefore epithelial cells are not protected against gastric acid

Question 25

How does urea go across outer membrane to periplasm

Answer 25

Through porins

Question 26

How does urea cross inner membrane into cytosol

Answer 26

Proton-gated urea channel = pH sensitive and ensures that the conversion of urea takes place when required

• 6 amino acid chains, 195 amino acids long
• disc-like

Question 27

Proton-gated urea channel are ______________

Answer 27

pH sensitive

Question 28

What pH value is acid neutralising system not active

Answer 28

Above 6.5

Question 29

Equation of the hydrolysis of urea

Answer 29

urea + water = ammonia + carbon dioxide

Question 30

What does ammonia act as in the periplasm

Answer 30

Base

Question 31

What does CO2 act as in the periplasm

Answer 31

Converts to bicarbonate ions (using carbonic anhydrase) = help buffer periplasmic pH

Question 32

Where is ammonia + carbon dioxide form

Answer 32

Cytosol

Question 33

What does a serology-based test require

Answer 33

Blood sample to test the prescence of patient antibodies recognising H.pylori antigens

Question 34

Where is the blood test based

Answer 34

Laboratory

- ELISA (enzyme-linkedimmunosorbent assay)