LIFSCI 7C XL - Animation: G protein-coupled receptors, Signal amplification, & Cell Signaling: 3D Animation

Which of the following could lead to a prolonged increase in heart rate, even in the absence of an external signal? Choose all that apply.

-An inability of a G-protein to hydrolyze GTP -An inability to inactivate protein kinase A

In the example of adrenaline signaling used in the animation, suppose each amplification step produces hundredfold active molecules. How many total modified protein target molecules result from a single activated signal receptor?

1,000,000

Arrange the events in the stimulation of heart muscle in order from earliest (1) to latest (5). Note that this question does not list every step in the pathway, but the steps presented should be arranged in order.

1. Activation of G-proteins 2. Activation of adenylyl cyclase 3. Conversion of ATP into cyclic AMP 4. Activation of protein kinase A 5. Phosphorylation of proteins that induce contraction in muscle cells

In the example of adrenaline signaling used in the animation, suppose each amplification step produces hundredfold active molecules. A signaling pathway resulting from a single activated signal receptor results in the consumption of _______ molecules of GTP and _______ molecules of ATP.

100; 1,010,000

Which of the following statements best summarizes the function of G protein-coupled receptors?

A signal present on the outside of the cell leads to a change on the inside of the cell

In the example of adrenaline signaling, which steps represent an amplification of the signal?

Activated receptor activates G proteins, activated adenylyl cyclase produces cAMP, active protein kinase A phosphorylates target proteins

Which of the following steps does not result in an amplification of the signal information?

Activation of adenylyl cyclase by active G protein

The primary advantage of a signaling cascade is that it:

Allows a large intracellular response from a small number of extracellular signal molecules

Adrenaline stimulates an increase in heart rate by binding to:

G-protein coupled receptors on the surface of cardiac muscle cells

The alpha subunit of a G-protein is free to diffuse in the plane of the membrane when:

GDP is exchanged for GTP

Termination of the adrenaline signal begins when:

GTP bound to the G-protein alpha subunit is hydrolyzed to GDP and Pi

When a G protein-coupled receptor binds a signal molecule, it activates a G protein. The active G protein is bound to a molecule of _______, and in its active state can _________.

GTP; activate another target protein

If a mutation caused the G protein to become permanently bound to GTP, what result can be predicted?

It constantly signals its pathway to be "on"

The type of signaling cascade shown in the video directly affects which of these animal tissue types?

Muscle

G protein-coupled receptors are found:

On the cell surface

When an appropriate signal binds to a G protein-coupled receptor, what is the best description of how the information is passed across the plasma membrane?

Signal binding causes a conformational change in the cytoplasmic portion of receptor protein