Advanced Placement (AP) Biology Practice Exam

What is the primary function of F protein-coupled receptors?

1. Relaying non-specific signals

2. Binding to pathogens

3. Relaying signals from receptors to intracellular pathways

4. Modulating apoptosis signals

The correct answer is: Relaying signals from receptors to intracellular pathways

F protein-coupled receptors primarily function to relay signals from external stimuli to intracellular pathways. These receptors are integral membrane proteins that detect various molecules outside the cell, such as hormones, neurotransmitters, and other signaling molecules. Upon binding to these ligands, the receptors undergo a conformational change that activates intracellular signaling cascades, typically involving G-proteins. This activation can lead to a range of physiological responses within the cell, including changes in gene expression, enzyme activity, or other cellular functions. This signaling mechanism is crucial for the cell's ability to respond to its environment and communicate effectively with other cells, making F protein-coupled receptors key players in many biological processes. Their role is not limited to any specific pathway, allowing for a versatile response to numerous signals, which underscores their importance in maintaining cellular function and homeostasis.