7. Cannabinoids, extracted from the cannabis plant bind to G-protein coupled rec

Question

7. Cannabinoids, extracted from the cannabis plant bind to G-protein coupled receptors. There are
similar receptors in human cells within the brain. However, instead of activating adenylyl cyclase,
stimulation of the receptor was found to inhibit the enzyme. Given this information, answer the
following questions. (3 points)
A. Would one expect cAMP levels to rise in brain cells stimulated with a cannaboid? Yes or
No (1 point)
___________________
B. Would arrestin need to ever bind the G-protein coupled receptor? (1 point)
___________________
C. What would happen to adenylyl cyclase in those cells if the G-alpha subunit was mutated
so it could not hydrolyse GTP? (1 point)
___________________
8. To test tight junction function, a small, water-soluble fluorescent dye molecule (Shine331)
was added to cells in the upper well of a transwell (Boyden chamber), and the amount the
fluorescent molecule that passed to the lower chamber was measured. The effect of a
Hormone on tight junction function was assessed by adding the Hormone to the cells in the
upper well at the concentrations indicated in panel A (left) (for 16 hours). The Hormone was
also added at 100 ng/mL for the times indicated in a separate experiment in panel B (right).
The asterisks indicate statistical significance (95% confidence, p<0.05) in the comparison of
Hormone treated versus the untreated control cells. Answer the following questions: (5 points
total)

A. What is the effect of hormone addition on Shine331 transport AND on tight junction
function in panel A? (2 points)
B. What is the effect of hormone addition on tight junction function over time in panel B?
Be specific. (2 points)
C. What specific function of tight junctions is tested using Shine331? (1 point)

Explanation / Answer

7.A. No
B. Yes, arrestin need to ever bind the G-protein coupled receptor
C. cAMP is not produced. cAMP is always at low concentration.

8. A. Transport of shine331 is decreased when increasing the concentration of hormone.
B. There is no transport of shine331 after addition of hormone and it closes the tight junction. Tight junction is closed and inhibited the movement of shine331.

C. Whether Tight junction is allowing molecule-shine331 across the cell or not.

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