Question

If one homogenizes liver cells, separates the membranes from the cytoplasm, and then adds epinephrine to only the cytoplasmic portion

A. cAMP will be produced B. G-proteins will be activated C. adenylylcyclase will be activated D. calcium ions will be produced E. none of these

Answer 1

Answer is E. none of the above.

Epinephrine acts on ⍺1,⍺2,β1,β2 receptors.these receptors act as binding sites of epinephrine.These are all G protein coupled receptors which acts by sending signals into the cytoplasm of the cell through secondary messengers like adenylyl cyclase,diacylglycerol and calcium.

As the cell membrane is separated from the cytoplasm , there is no connectivity between cell membrane and cytoplasm.therefore the cytoplasm cannot receive any signals from the cell membrane.

Now when you add Epinephrine to the cytoplasm ,epinephrine cannot bind to any binding sites(receptors are all present in the cell membrane and not in the cytoplasm). so no action is seen on adding  epinephrine to the cytoplasm.