Cell Signaling Pathways Quiz

<p>Inositol phospholipid pathway (A)</p> Signup and view all the answers

<p>Continuous production of cyclic AMP (A)</p> Signup and view all the answers

<p>cAMP phosphodiesterase (B)</p> Signup and view all the answers

<p>Serine and threonine (A)</p> Signup and view all the answers

<p>Diacylglycerol (DAG) (C)</p> Signup and view all the answers

<p>It acts as an intracellular messenger triggering various biological processes (B)</p> Signup and view all the answers

<p>To mediate effects of cyclic AMP by phosphorylating proteins (C)</p> Signup and view all the answers

<p>Gene transcription and hormone synthesis (C)</p> Signup and view all the answers

<p>InsP3 and DAG (B)</p> Signup and view all the answers

<p>Protein kinases and phosphatases (A)</p> Signup and view all the answers

<p>It mediates effects of Ca2+ through interaction with transducer proteins. (A)</p> Signup and view all the answers

<p>The activated βγ complex opens K+ channels after receptor activation. (C)</p> Signup and view all the answers

<p>The fertilization of an egg by a sperm. (D)</p> Signup and view all the answers

<p>Calmodulin (D)</p> Signup and view all the answers

<p>Amplifying the signal and specificity of the response. (C)</p> Signup and view all the answers

<p>The α subunit reassociates with the βγ complex to reform an inactive G protein. (D)</p> Signup and view all the answers

<p>It triggers the dissociation of the G-protein into the active forms. (D)</p> Signup and view all the answers

<p>Latency of the response. (C)</p> Signup and view all the answers

<p>It catalyzes the formation of cyclic AMP. (A)</p> Signup and view all the answers

<p>GDP is released from Gα and GTP is bound. (C)</p> Signup and view all the answers

<p>They enhance signal transduction efficiency by organizing proteins. (D)</p> Signup and view all the answers

<p>Cyclic AMP (B)</p> Signup and view all the answers

<p>Hydrolysis of GTP to GDP by the alpha subunit. (D)</p> Signup and view all the answers

<p>It returns to an inactive state. (B)</p> Signup and view all the answers

<p>Inositol triphosphate and diacylglycerol (D)</p> Signup and view all the answers

<p>They inhibit cAMP phosphodiesterase activity. (B)</p> Signup and view all the answers

<p>It reverts to its inactive state. (D)</p> Signup and view all the answers

<p>One alpha, one beta, and one gamma subunit (A)</p> Signup and view all the answers

<p>By exchanging GDP for GTP (A)</p> Signup and view all the answers

<p>To inhibit receptor interactions with G-proteins. (A)</p> Signup and view all the answers

<p>Signal transduction efficiency decreases when scaffolding proteins are absent. (B)</p> Signup and view all the answers

<p>Activation of the receptor (B)</p> Signup and view all the answers

<p>cAMP is rapidly cleaved, leading to decreased levels. (D)</p> Signup and view all the answers

<p>Multiple pathways can interact with each other. (B)</p> Signup and view all the answers

<p>They consist of a single polypeptide chain threading through the lipid bilayer seven times. (C)</p> Signup and view all the answers

<p>They hydrolyze GTP to GDP, activating downstream target proteins. (D)</p> Signup and view all the answers

<p>Secondary messenger (A)</p> Signup and view all the answers

<p>It undergoes a conformational change, activating downstream signaling proteins. (D)</p> Signup and view all the answers

<p>To anchor the G-protein to the plasma membrane and assist in signaling. (C)</p> Signup and view all the answers

<p>They are specific to particular sets of receptors and their downstream target proteins. (C)</p> Signup and view all the answers

<p>They can be proteins, small peptides, or derivatives of amino acids or fatty acids. (C)</p> Signup and view all the answers

<p>The presence of covalently attached lipid anchors on the α and γ subunits. (D)</p> Signup and view all the answers

G-protein-linked receptors are a large family of cell-surface receptors that bind to a variety of extracellular signal molecules, such as hormones, neurotransmitters, and local mediators.

All G-protein-linked receptors have a similar structure: a single polypeptide chain that crosses the cell membrane seven times. This seven-transmembrane structure allows them to interact with both extracellular signals and intracellular signaling pathways.

G-proteins are heterotrimeric proteins, meaning they consist of three subunits: alpha (α), beta (β), and gamma (γ). The alpha subunit binds to GTP and can hydrolyze it to GDP and phosphate.

When an extracellular signal molecule binds to a G-protein-linked receptor, the receptor undergoes a conformational change that activates the G-protein. The activated G-protein then interacts with downstream effector proteins to initiate a signaling cascade.

The alpha subunit of the G-protein is responsible for activating downstream effector proteins. Different types of G-proteins activate different effector proteins, leading to a diverse range of cellular responses.

Primary messengers are extracellular signaling molecules that bind to receptors on the cell surface. Secondary messengers are small molecules that are generated inside the cell in response to the activation of a receptor. These messengers act as intracellular signals, relaying information to other components of the cell.

G-proteins are highly specific: different G-proteins interact with different receptors and activate different downstream effector proteins. This specificity ensures that each signal molecule triggers the appropriate cellular response.

The diversity of G-protein-linked receptors and G-proteins allows cells to respond to a wide range of extracellular signals. This diversity is essential for coordinating complex cellular processes and maintaining normal physiological function.

Activated by a ligand binding to a GPCR, the G protein releases GDP and binds GTP, leading to its activation and dissociation into the α subunit and βγ complex.

A transmembrane protein that produces cAMP, a small intracellular signaling molecule.

A type of signaling pathway that involves a G protein interacting with adenylate cyclase.

A second messenger that activates protein kinase A (PKA) in many pathways.

A type of cell surface receptor with seven transmembrane helices. It activates G proteins by binding to ligands.

The activated α subunit of the G protein binds to and activates adenylate cyclase, leading to cAMP production.

A complex of β and γ subunits that can also regulate target proteins.

The process by which a signal is received by a cell and transduced into a response.

cAMP, a secondary messenger, is synthesized from ATP by adenylyl cyclase, an enzyme activated by the activated alpha subunit of a G-protein.

cAMP phosphodiesterase rapidly converts cAMP to AMP, helping to eliminate the signal and restore the cell to its resting state.

cAMP-dependent protein kinase (PKA) is the main mediator of cAMP's effects. It phosphorylates various cellular proteins, altering their activity.

PKA phosphorylates gene regulatory proteins, activating the transcription of a specific set of target genes.

The inositol phospholipid pathway activates phospholipase C, a membrane-bound enzyme that cleaves phosphatidylinositol, generating two important second messengers: inositol-1,4,5-trisphosphate (InsP3) and diacylglycerol (DAG).

InsP3 triggers the release of calcium ions (Ca2+) from intracellular stores, leading to a rise in intracellular Ca2+ concentration.

Diacylglycerol (DAG) activates protein kinase C (PKC), another important signaling protein.

Ca2+ acts as a crucial intracellular messenger, playing a vital role in numerous biological processes by binding and activating various proteins, including calmodulin-binding proteins, specific kinases, and phosphatases.

A type of protein that binds to calcium ions (Ca2+) and acts as a mediator of calcium signaling. It is involved in a wide range of cellular processes, including muscle contraction, neurotransmission, and gene expression.

The G protein subunit responsible for activating downstream effector proteins. The activation of the G protein is triggered by the exchange of GDP for GTP.

The process in which a signal is received by a cell and converted into a response.

A type of signaling pathway that involves the production of inositol triphosphate (IP3) and diacylglycerol (DAG) as second messengers. It is often triggered by the activation of G protein-coupled receptors.

A specialized type of G protein that regulates the opening of potassium (K+) channels in the membrane of cardiac muscle cells. This affects the heart's rhythm and contraction.

A specific type of intracellular signaling molecule that is produced by the enzyme adenylate cyclase. It acts as a second messenger in many cellular pathways, including those involved in metabolism, growth, and development.

They act as intracellular signals, relaying information to other components of the cell.

It describes how a signal is amplified within a cell, leading to a stronger response. This can occur through various mechanisms, such as the activation of multiple downstream signaling molecules.

Proteins that act like a bridge, connecting multiple signaling proteins within the same pathway.

The process by which a cell stops responding to a signal, ensuring that signaling pathways are transient and do not continue unnecessarily.

The activated Gα subunit hydrolyzes its bound GTP to GDP, returning to its inactive state and dissociating from adenylate cyclase.

An enzyme responsible for breaking down cAMP, a key second messenger in signal transduction.

A phosphorylated receptor can bind to β-arrestin, preventing further interaction with G-proteins and effectively stopping the signal.

The ability of cells to respond differently to the same signaling molecule due to variations in their protein composition and signaling pathways.

Interactions between different signaling pathways, allowing cells to coordinate complex responses to multiple stimuli.

The presence of branching points in a signaling pathway, allowing for the activation of multiple downstream targets.

β-Arrestin is a protein that helps shut off G protein-coupled receptor (GPCR) signaling by promoting its endocytosis and by binding to phosphodiesterase, which breaks down cAMP.

V. cholera enterotoxin modifies the α subunit of the Gs protein, preventing its inactivation by GTPase. This keeps the Gs permanently activated, leading to continuous cAMP production and severe diarrhea.

Protein phosphatases reverse the effects of protein kinases by removing phosphate groups from proteins. They are essential for turning off signaling cascades by returning target proteins to their original, inactive states.

cAMP activates protein kinase A (PKA), which phosphorylates target proteins to activate them. When the signal needs to be switched off, protein phosphatases remove these phosphate groups, deactivating the target proteins and reversing the signal.

G protein-coupled receptors (GPCRs) are a large family of cell surface receptors that activate G proteins. They are involved in various signaling pathways and play a crucial role in regulating a wide range of cellular processes.