Lecture 17

Question 1

How does Vibrio Cholerae cause diarrhoea and death?

Answer 1

Infects mucosal epithelial cells, which prevents the normal function therefore diarrhoea.

Question 2

What is the target of the cholera toxin?

Answer 2

The G-protein stimulator.

Question 3

How does cholera toxin work?

Answer 3

Cl- secretion into the gut is controlled by Gs protein and cAMP. Cholera toxin prevents GTP breakdown to GDP. too much Cl- in the gut lumen therefore diarrhoea

Question 4

What is the mechanism of action?

Answer 4

Cholera modifies the Gs protein via ADP ribosylation. Therefore always switches on, overproduction of cAMP and excess Cl- is pumped into the gut lumen. This causes water and other salts to be pumped out causing dehydration and loss of electrolytes

Question 5

How does C. botulinum work?

Answer 5

Botulinum toxin is a highly toxic substance, it targets the synaptic signalling at the neuromuscular junction. It blocks the release of acetylcholine into the neuromuscular junction. Causing paralysis

Question 6

Describe Muckle Wells syndrome.

Answer 6

Rare inflammatory autosomal dominant condition. High levels of IL-1 due to amplified immune response.

Question 7

What is the effect of a altered chloride ion channel in CF

Answer 7

There is a deletion in the gene for the cAMP-dependent chloride channel pump in epithelial cells. Cl- is not pumped out of cells thus increased viscosity of the mucus.

Question 8

What are the two ways of cancer forming?

Answer 8

Too much signalling (oncogenes) and Too little signalling (tumour suppressors)

Question 9

Describe EGF in breast cancer.

Answer 9

Increased levels of EGF at the PM and the signal for cell division is permanently on

Question 10

What does Herceptin do?

Answer 10

Blocks the over-activated EGF receptor tyrosine kinase

Question 11

What is the cause of Parkinson’s disease?

Answer 11

Lack of dopamine signalling via its GPCR