Vibrio cholerae produces a toxin that binds to a plasma membrane receptor on intestinal cells of the host - VCE - SSCE Biology - Question 12 - 2011 - Paper 1
Question 12
Vibrio cholerae produces a toxin that binds to a plasma membrane receptor on intestinal cells of the host. The toxin permanently activates the G protein in target ce... show full transcript
Worked Solution & Example Answer:Vibrio cholerae produces a toxin that binds to a plasma membrane receptor on intestinal cells of the host - VCE - SSCE Biology - Question 12 - 2011 - Paper 1
Step 1
A. disrupts normal signal transduction in the cell.
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Answer
The cholera toxin binds to the G protein-coupled receptor, leading to continuous activation of the G protein which disrupts normal signal transduction pathways within the cell. This abnormal activation causes the cells to secrete excessive amounts of water and electrolytes, which leads to severe dehydration.
Step 2
B. is an example of a second messenger molecule.
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Answer
While cholera toxin affects second messenger pathways by activating adenylate cyclase leading to increased cAMP levels, it itself is not a second messenger. It is a protein that modulates the activity of second messengers.
Step 3
C. is a lipid-soluble molecule.
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Answer
Cholera toxin is a protein and not lipid-soluble. Lipid-soluble molecules typically pass easily through cell membranes, whereas proteins do not.
Step 4
D. acts as a neurohormone.
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Cholera toxin does not function as a neurohormone. Neurohormones are typically released by neurons into the blood stream, whereas cholera toxin directly impacts cellular signaling.
