Question

In photoreceptor cells in the retina, light is sensed by a GPCR called rhodopsin. Which of the following represents the events that take place after the activation of rhodopsin?

Choose one:

1. activation of G protein, activation of phosphodiesterase, breakdown of cyclic GMP, opening of ion channels, change in membrane potential
2. activation of G protein, activation of phosphodiesterase, breakdown of cyclic GMP, closing of ion channels, change in membrane potential
3. inactivation of G protein, inactivation of phosphodiesterase, production of cyclic GMP, closing of ion channels, change in membrane potential
4. activation of G protein, activation of phosphodiesterase, production of cyclic GMP, opening of ion channels, change in membrane potential
5. activation of G protein, activation of guanylyl cyclase, production of cyclic GMP, opening of ion channels, change in membrane potential

Which serve as direct targets for G proteins?

Choose one or more:

1. 1) genes
2. 2)enzyme-coupled receptors
3. 3)ion-channel-coupled receptors
4. 4)ion channels
5. 5)membrane-bound enzymes

Answer 1

b.)

In photoreceptor cells in the retina, light is sensed by a GPCR called rhodopsin. Which of the following represents the events that take place after the activation of rhodopsin

is

activation of G protein, activation of phosphodiesterase, breakdown of cyclic GMP, closing of ion channels, change in membrane potential

opening of ion channel in option 1, 4 and 5 put them wrong

since activation of G protein and phosphodiesterse occurs option 3 is also wrong as it tells otherwise.

direct targets for G proteins

3)ion-channel-coupled receptors

to which it binds and activates also.