Epinephrine is ______ and binds to cell-surface receptors to activate ____ _____ and produce the second messenger ______.

Epinephrine is ______ and binds to cell-surface receptors to activate ____ _____ and produce the second messenger ______.

• A. lipophilic, phospholipase C, IP3
• B. hydrophilic, adenylate cyclase, cAMP
• C. hydrophobic, adenylate cyclase, cGMP
• D. hydrophilic, phospholipase C, cAMP

Answer: (B)

Epinephrine is known to be a hydrophilic molecule, which means it is water-soluble and cannot easily pass through the lipid bilayer of cell membranes. Instead, it binds to cell-surface receptors, specifically adrenergic receptors, which are G protein-coupled receptors. Upon binding to these receptors, epinephrine activates adenylate cyclase, an enzyme that catalyzes the conversion of ATP to cyclic AMP (cAMP), which serves as a second messenger within the cell. cAMP plays a crucial role in signal transduction pathways, leading to various physiological effects, such as increased heart rate and energy mobilization. This understanding of epinephrine's nature as a hydrophilic molecule and its interaction with adenylate cyclase to produce cAMP is foundational in biochemistry and cellular biology, highlighting how extracellular signals can influence cellular responses through secondary messengers.

Epinephrine is known to be a hydrophilic molecule, which means it is water-soluble and cannot easily pass through the lipid bilayer of cell membranes. Instead, it binds to cell-surface receptors, specifically adrenergic receptors, which are G protein-coupled receptors.

Upon binding to these receptors, epinephrine activates adenylate cyclase, an enzyme that catalyzes the conversion of ATP to cyclic AMP (cAMP), which serves as a second messenger within the cell. cAMP plays a crucial role in signal transduction pathways, leading to various physiological effects, such as increased heart rate and energy mobilization.

This understanding of epinephrine's nature as a hydrophilic molecule and its interaction with adenylate cyclase to produce cAMP is foundational in biochemistry and cellular biology, highlighting how extracellular signals can influence cellular responses through secondary messengers.