Cell Biology: Signal Transduction Mechanisms

<p>Binding is irreversible (C)</p> Signup and view all the answers

<p>To act as a molecular switch that can be turned on or off (C)</p> Signup and view all the answers

<p>Ligand binding causes a conformational change in the receptor, which in turn activates the G-protein (B)</p> Signup and view all the answers

<p>G-protein linked receptors activate G-proteins, while protein kinase linked receptors activate protein kinases (C)</p> Signup and view all the answers

<p>G-protein linked receptors are involved in a wide variety of cellular processes (B)</p> Signup and view all the answers

<p>To activate a downstream signaling pathway by interacting with other proteins. (C)</p> Signup and view all the answers

<p>GTP binds to the Gα subunit, causing it to detach from the Gβγ complex and activate downstream signaling. (C)</p> Signup and view all the answers

<p>The receptor undergoes a conformational change that activates the G protein. (D)</p> Signup and view all the answers

<p>The Gα subunit can activate different downstream pathways depending on the type of G protein and cell. (C)</p> Signup and view all the answers

<p>The GTP bound to the Gα subunit is hydrolyzed to GDP, causing the G protein to inactivate. (D)</p> Signup and view all the answers

<p>cAMP-dependent protein kinase A (PKA) (C)</p> Signup and view all the answers

<p>Phosphorylation can alter the activity of downstream target proteins, influencing the cellular response. (B)</p> Signup and view all the answers

<p>The receptor activates the G protein, which then triggers downstream signaling events. (C)</p> Signup and view all the answers

<p>Endocrine signals act on distant targets, while paracrine signals act on nearby cells. (C)</p> Signup and view all the answers

<p>Autocrine signal (C)</p> Signup and view all the answers

<p>Receptors bind to signaling molecules and initiate a signal transduction cascade. (A)</p> Signup and view all the answers

<p>A molecule produced after a ligand binds to a receptor, which initiates intracellular signaling events. (D)</p> Signup and view all the answers

<p>All of the above (D)</p> Signup and view all the answers

<p>It irreversibly activates G proteins, leading to excessive cAMP production and fluid secretion. (D)</p> Signup and view all the answers

<p>The conversion of an extracellular signal into an intracellular response. (A)</p> Signup and view all the answers

<p>G proteins act as molecular switches, cycling between active and inactive states to regulate downstream signaling events. (C)</p> Signup and view all the answers

<p>It synthesizes cAMP from ATP. (D)</p> Signup and view all the answers

<p>It causes the α subunit to detach from the receptor and bind to adenylyl cyclase. (B)</p> Signup and view all the answers

<p>cAMP stimulates glycogen breakdown, resulting in increased glucose release. (D)</p> Signup and view all the answers

<p>cAMP levels increase as adenylyl cyclase is stimulated. (B)</p> Signup and view all the answers

<p>Stimulating cAMP synthesis by activating the G protein Gs. (C)</p> Signup and view all the answers

<p>It prevents the G protein Gs from hydrolyzing GTP to GDP, leading to sustained cAMP production. (D)</p> Signup and view all the answers

<p>They inhibit the activity of phosphodiesterase, leading to accumulation of cAMP. (B)</p> Signup and view all the answers

<p>When the G protein Gs is inactive and cannot hydrolyze GTP to GDP. (B)</p> Signup and view all the answers

The process through which cells translate receptor-ligand interactions into cellular responses.

Chemical messengers that act at a distance from their site of production.

Signals released by cells that act on nearby cells or tissues.

Type of local mediator signals that diffuse to target nearby tissues.

Mediators that act on the same cell that produces them.

A molecule that binds to a receptor to initiate a signaling process.

Small molecules or ions produced inside the cell after receptor-ligand binding that trigger further signaling events.

Proteins activated by receptors that help transmit signals inside the cell.

The specific connection of a ligand to its receptor through non-covalent bonds.

The process where one ligand triggers a larger cellular response.

The breakdown of glycogen in the liver triggered by epinephrine.

Receptors can be categorized based on their mechanisms of action.

A family of receptors that activate G-proteins upon ligand binding.

The alteration in a receptor's shape following ligand binding.

The 'on' state of G-proteins occurs when bound to GTP; 'off' state with GDP.

A receptor that activates a G protein upon ligand binding.

Molecules that G proteins bind to; GDP is inactive, GTP is active.

Formed when an activated G protein binds to a receptor that has changed conformation.

A second messenger involved in many signaling pathways, particularly in activating PKA.

Protein Kinase A, activated by cAMP to phosphorylate target proteins.

Occurs when GTP is hydrolyzed to GDP, shutting down the signaling process.

An enzyme that converts ATP to cAMP when activated by G proteins.

The activated G protein subunit that stimulates adenylyl cyclase activity.

An enzyme that breaks down cAMP into AMP, terminating the signal.

cAMP can stimulate glycogen breakdown, strengthen heart contraction, or inhibit smooth muscle contraction.

A toxin that modifies Gs protein, preventing it from hydrolyzing GTP, leading to excess cAMP and salt secretion in the intestine.

Increased levels of cAMP can occur by stimulating synthesis or inhibiting breakdown through phosphodiesterase inhibitors.