Map sapling learning iototransduction uses a signal transduction cascade similar

ID: 68754 • Letter: M

Question

Map sapling learning iototransduction 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 11-cis-retinal converted to all-trans-retinal cGMP PDE converts cGMP to biologically inactive 5'-GMP Tasubunit encounters PDE Ta subunit hydrolyzes GTP lcGMPl decreases cGMP-gated ion channels close high [ca inhibits guanylyl cyclase transducin dissociates into Ta-GTP and T GDP bound to transducin By PDE bound to inhibitory subunit [Ca2"] declines guanylyl cyclase converst GTP to cGMP

Explanation / Answer

Photo transduction increase

Photo transduction does not increase

11-cis retinal converted to all trans-retinal

cGMP PDE converts cGMP to biological inactive 5’-GMP

T subunit encounters PDE

cGMP decrease

T subunit hydrolyzes GTP

high Ca2+ inhibits guanylul cyclise

cGMP-gated ions channels close

Ca2+ declines

Transduction dissociates into T-GTP and Ty

Guanylyl cyclise converst GTP to cGMP

GDP bound to transducin

PDE bound to inhibitory subunit