1. Compare and contrast channel proteins and the classes of carrier proteins (e. g., uniporter, symporter, and antiporter) including the relative direction of molecule movement and any associated energetic needs. Which protein class would nicotinic acetylcholine receptors (nAChRs) be associated with? 2. In cardiac muscle, acetylcholine binds to muscarinic acetylcholine receptors (mAChRs), which are G-protein coupled receptors, which elicit a signal transduction pathway that induces cardiac muscle to relax. Outline how G-protein coupled receptors induce signal transduction pathways including relevant secondary messengers.
3. Interpret Dr. Peterson’s statement that active transport is essential for facilitated diffusion of Na+ ions to occur in muscle cells. How are Na+/K+ pumps involved in this process? Sketch a Na+/K+ pump indicating conformational changes and energy usage steps and identify ions that are moved during the cyclic process.
4. Generally, after neurotransmitters are released in the neuromuscular junction, many of the neurotransmitters or some of their components are recycled by a reuptake mechanism inherent in the pre-synaptic neuron. Considering that the reuptake mechanism is often a sodium-dependent process that utilizes membrane potential, what type of membrane transport might you expect to be in play here?