THE CELL
CELL COMMUNICATION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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the intact cells contained a second messenger
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the intact cells contained more glycogen
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the intact cells had fewer receptors for epinephrine
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the intact cells contain more calcium ions
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Detailed explanation-1: -This happens because activation of glycogen phosphorylase requires a membrane-bound cell. The receptors are present on membranes of the cell. Thus, the enzyme requires an intact receptor to bind and initiate the signal transduction cascade.
Detailed explanation-2: -Which observation suggested to Sutherland the involvement of a second messenger in epinephrine’s effect on liver cells? Glycogen breakdown was observed only when epinephrine was administered to intact cells.
Detailed explanation-3: -For example, when epinephrine binds to beta-adrenergic receptors in cell membranes, G-protein activation stimulates cAMP synthesis by adenylyl cyclase. The newly synthesized cAMP is then able to act as a second messenger, rapidly propagating the epinephrine signal to the appropriate molecules in the cell.
Detailed explanation-4: -Second messengers are small molecules and ions that relay signals received by cell-surface receptors to effector proteins.