In the sea snail experiment (Aplysia), which of the following is TRUE regarding short-term sensitization? Question 9 options: Phospholipase C triggers the activation of protein kinase A Protein kinase A inhibits potassium channels and prolongs activation of voltage-gated calcium channels The production of cyclic AMP is blocked by serotonin The motor neuron releases serotonin Protein kinase A facilitates the entrance of potassium
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Let’s say you are conducting experiments to determine a cell’s signaling pathway involved in opening an ion channel in response to drug A, which is a hydrophilic compound. You are pretty certain drug A binds to a GPCR. You give the drug and the cellular response is the opening of a chloride channel and chloride effluxes out of a cell. In a separate experiment, you treat the cell with the compound forskolin, which directly activates adenylate cyclase, and notice that the chloride channel opens and chloride effluxes out of the cell. Now you also pretreat the cell with the bacterial toxin cholera toxin and then treat the cell with drug A. You notice the cell does not efflux chloride and the chloride channel is not activated. You also do a separate experiment where you give the drug A and along with the chemical EGTA (EGTA can cross the cell membrane and bind up cytosolic calcium) but the cell effluxes chlorine just as much as when you give the drug A alone. What can you say about the signaling mechanism? The signal from drug A is transduced by G stimulatory protein (Gs) and the receptor is coupled to Gs. Protein Kinase C is probably involved in the process of drug A stimulated chloride efflux. Protein Kinase A is probably involved in the process of drug A induced chloride efflux. A and C
Josee P.
Fill in the blanks: Use the drop down menus to select the best answer. Two different neuromodulators each activate different kinases: Kinase A and Kinase B. Kinases [A. phosphorylate or B. dephosphorylate] proteins. Both kinases perform this function on voltage-gated sodium channels, which are critical to the generation of the action potential. If Kinase A decreases voltage-gated sodium channel conductance and Kinase B slows inactivation of voltage-gated sodium channels, you would expect Kinase A to [A. hasten decreases in, B. decrease the magnitude of, C. increase the magnitude of, D. slow decreases in] sodium currents across voltage-gated sodium channels after their opening. You would expect Kinase B to [A. hasten decreases in, B. decrease the magnitude of, C. increase the magnitude of, D. slow decreases in] sodium currents across voltage-gated sodium channels after their opening.
Supreeta N.
Cholera toxin locks the Gs subunit into an active state, in that GTP is bound and cannot be hydrolyzed back to GDP to turn off the subunit. What effect will cholera toxin have in the cell? Increased cyclic AMP levels will lead to increased protein kinase A activation. Activated adenylyl cyclase will lead to decreased cyclic AMP levels. The Gs subunit will more strongly inhibit adenylyl cyclase. Decreased cyclic AMP levels will lead to decreased protein kinase A activation. Inhibited adenylyl cyclase will lead to increased cyclic AMP levels. In the marine mollusk, Aplysia, serotonin binds to a G-protein-coupled receptor and activates a Gs subunit. The resulting activation of PKA leads to phosphorylation and closure of K+ channels. What effect would this have on the cell? No change in K+ ion flow or membrane potential Decreased K+ efflux depolarizing the cell Decreased K+ efflux hyperpolarizing the cell Increased K+ efflux hyperpolarizing the cell Increased K+ efflux depolarizing the cell Which statement about protein kinases in the brain is most accurate? They amplify second messenger signals. Each has a regulatory domain that inhibits the catalytic domain. Most are important regulators of neuronal signaling. They can be activated only by second messengers. The catalytic domain of a protein kinase is always inhibited.
Suman K.
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