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+--- Thread: NonNBME Qn - samideb12 (/showthread.php?tid=658406)
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NonNBME Qn - samideb12 - ArchivalUser - 03-01-2012
Retinitis pigmentosa is a genetically heterogenous disease cixed by progressive photoreceptor degeneration and ultimately blindness.Mutations in more than 20 different genes have been identified in clinically affected patients .Recent studies have mapped and RP locus to the chromosomal location of a new candidate gene at 5q31.One might expect this gene to encode a polypeptide required for the activity of a(n):
A.Receptor tyrosine kinase
B.cGMP phosphodiesterase
C.Phospholipase
D.Adenylate cyclase
E.Protein kinase C
0 - ArchivalUser - 03-01-2012
BB
0 - ArchivalUser - 03-01-2012
not sure...B
0 - ArchivalUser - 03-01-2012
Yes ,cGMP PDE participates as a signaling molecule in the visual cycle of photoreceptor cells.What happens when cGMP is increased and decreased to the pathway?
0 - ArchivalUser - 03-01-2012
B.cGMP phosphodiesterase
0 - ArchivalUser - 03-01-2012
I know that Viagra can affect color vision because it is PDEI, so I would say if it is decreased, less signalling and vise versa
0 - ArchivalUser - 03-01-2012
Are you sure ???
0 - ArchivalUser - 03-01-2012
I am just assuming, based on Sildenafil SE, it causes green-blue color blindness.
0 - ArchivalUser - 03-01-2012
If you see in kaplan lecture ,the pathway activates cGMP PDE ,which lowers cGMP in response to light;the reverse is true in dark
0 - ArchivalUser - 03-01-2012
You are right, this is good point, and it needs analysis and deep thinking to come to a clear concept at least for me!