Question

With regard to G proteins, which of the following is NOT true?

A. Gsα triggers phospholipase C activation

B. Gα subunits can hydrolyze GTP

C. The Gβγ subunits block exposure of the G alpha switch domains

D. Both the Gα and Gβγ subunits can interact with downstream target proteins to propagate signals.

During the undershoot of the action potential, which IS NOT true?

A. Sodium channel inactivation is the reason for the absolute refractory period.

B. The undershoot arises because the cell is more permeable to sodium than it is at rest.

C. Potassium channel inactivation is why the cell recovers from the undershoot.

D. During the undershoot, the threshold potential is more negative than when the cell is at rest.

Which is NOT TRUE of fusion of the neurotransmitter vesicle with the plasma membrane?

A. Syntaxin binding to Synaptobrevin and triggers secretion.

B. Syntaxin binding to Synaptobrevin and directs secretory vesicles to the right location.

C. Calcium binding to synaptotagmin causes membrane fusion

D. The nerve terminal is the unique in depending on SNARE SNARE interactions to facilitate secretion

Answer 1

The G protein is the important part of the signaling cascade starts by the binding of the ligand to the G protein receptor. It has three subunits: Aplha, beta and gamma. The alpha subunit hydrolysis the GTP during signal transduction. During the moral starge all three subunits are bind together. During signal processing only alpha subunit can interact with downstream target proteins to propagate signals..

The answer is D.