Final answer:
In muscle, adrenaline stimulates the conversion of ATP to cAMP by adenylyl cyclase. cAMP serves as a second messenger, activating PKA, which then leads to glycogen breakdown. Thus, the correct answer is C. Adenylyl cyclase, cAMP, PKA.The correct answer is option C.
Step-by-step explanation:
In muscle, adrenaline causes the breakdown of glycogen. This requires adenylyl cyclase and cyclic AMP (cAMP) formation, leading to the activation of protein kinase A (PKA). Therefore, the correct answer is C. Adenylyl cyclase, cAMP, PKA.
This biochemical pathway begins when epinephrine binds to the ß-adrenergic receptors on the muscle cell, activating a G-protein, which then stimulates adenylyl cyclase. Adenylyl cyclase converts ATP to cAMP. The cAMP formed acts as a second messenger, activating PKA. PKA phosphorylates target enzymes that regulate glycogen metabolism.
This results in the activation of glycogen phosphorylase, which breaks down glycogen into glucose, and the inhibition of glycogen synthase, which prevents the synthesis of glycogen from glucose. Consequently, the muscle cell is provided with a quick supply of glucose for energy, particularly during the 'fight or flight' response triggered by a surge of adrenaline.The correct answer is option C.