Map sapling learning Phototransduction uses a signal transduction cascade simila
ID: 921299 • Letter: M
Question
Map sapling learning Phototransduction uses a signal transduction cascade similar to mechanisms stimulated by hormones and neurotransmitters. However, the visual sensory apparatus is stimulated by photons, and converts light energy into a nerve impulse. Determine whether each of the the following events increases phototransduction or does not increase phototransduction (either by not initiating a signal or by terminating the signal). The abbreviation cGMP is used for guanosine 3,5-cyclic monophosphate (cyclic GMP), and PDE is used for phosphodiesterase. Phototransduction increases Phototransduction does not increase CGMP) decreases rod cell membrane hyperpolarized high [Ca2 minhibits guanylyl cyclase transducin dissociates into TaGTP and T GDP bound to transducin PDE bound to inhibitory subunit Ca2 declines guanylyl cyclase converst GTP to cGMP 11-cis-retinal converted to all trans-retinal Ta subunit encounters PDE cGMP PDE converts cGMP Ta subunit hydrolyzes GTP to biologically inactive 5-GMP A Previous 3 Give Up & View Solution Check Answer Next Exit HintExplanation / Answer
Increase
[cGMP] decreases
Rod cell membrane hyperpolarized
High [Ca2+] inhibits guanylyl cyclase
transducin dissociates into T alpha GTP and T beta
11-cis-retinal converted to all trans-retinal
T alpha subunit encounters PDE
Decrases:
GDP bound to transducin
PDE bound to inhibitory subunit
[Ca2+] declines
Guanylyl cyclase convert GTP to cGMP
Talpha subunit hydrolyzes GTP