GPCR Activation and Cellular Signaling

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What is the primary function of GPCR activation in cellular signaling?

Production of second messengers (correct)

Conversion of ATP to cAMP

Degradation of second messengers

Opening of gated ion channels

Which of the following receptors leads to the activation of phosphoinositide second messenger system?

Insulin receptor

GABA receptor

a-adrenergic receptor (correct)

b-adrenergic receptor

Which G-protein is associated with adenylate cyclase activation?

Gqa

Gtg

Gti

Gsa (correct)

What is the resultant second messenger when phospholipase C is activated?

IP3 and DAG Signup and view all the answers

Which protein kinase is activated by adenylate cyclase?

PKA Signup and view all the answers

In the context of Gibbs free energy, what is ΔG°?

Free energy change under standard conditions Signup and view all the answers

Which process contributes to the termination of signaling effects?

GTPase activation Signup and view all the answers

According to the laws of thermodynamics, what is stated in the second law?

Every energy transfer increases entropy Signup and view all the answers

Which intermediate is formed after isocitrate in the TCA cycle?

A-ketoglutarate Signup and view all the answers

Which enzyme catalyzes the conversion of malate to oxaloacetate in the TCA cycle?

Malate DH Signup and view all the answers

What stimulates gluconeogenesis during low glucose levels?

Glucagon Signup and view all the answers

Which tissue is the primary site for gluconeogenesis?

Liver Signup and view all the answers

What is produced during the conversion of succinate to fumarate in the TCA cycle?

FADH2 Signup and view all the answers

Which of the following statements about the TCA cycle is NOT correct?

NADH is not produced in the CO2 producing steps. Signup and view all the answers

Which precursor is involved in gluconeogenesis and primarily sourced from muscle tissue?

Alanine Signup and view all the answers

Which of the following regulates the TCA cycle by inhibiting certain steps?

ATP Signup and view all the answers

Which enzymes catalyze the irreversible steps of gluconeogenesis?

PEP carboxykinase Signup and view all the answers

How many ATP equivalents are required to synthesize one molecule of glucose?

4 ATP, 2 GTP, and 2 NADH Signup and view all the answers

Which of the following substances inhibits Fructose 1,6-bisphosphatase?

AMP Signup and view all the answers

Which complex in the electron transport chain uses FMN as a cofactor?

Complex I Signup and view all the answers

What is the role of CoQ in the electron transport chain?

It carries electrons from Complexes I and II to Complex III Signup and view all the answers

What activates gluconeogenesis through allosteric regulation?

Acetyl CoA Signup and view all the answers

Which electron carrier is hydrophilic and found in the intermembrane space?

Cytochrome C Signup and view all the answers

What is primarily responsible for the generation of the electrochemical gradient during electron transport?

Transfer of electrons through complexes Signup and view all the answers

What distinguishes an endergonic reaction from an exergonic reaction?

Endergonic reactions have a positive ΔG, while exergonic reactions have a negative ΔG. Signup and view all the answers

How is the actual ΔG of a cellular reaction calculated using ΔG° and cellular concentrations?

By using the equation ΔG = ΔG° + RT ln(Q) where Q is the reaction quotient. Signup and view all the answers

Which term describes compounds with free energy of hydrolysis equal to or higher than ATP?

High energy compounds Signup and view all the answers

What is the role of the various phosphate groups in ATP?

They contribute to the high energy bonds due to significant electrostatic repulsion. Signup and view all the answers

What characterizes substrate-level phosphorylation?

It couples with the release of free energy to produce ATP or GTP. Signup and view all the answers

Which GLUT transporter is specifically insulin-dependent?

GLUT-4 Signup and view all the answers

Which of the following is NOT a rate-limiting enzyme in glycolysis?

Lactate dehydrogenase Signup and view all the answers

What is the total energy output of glycolysis under aerobic conditions?

6-8 ATP molecules Signup and view all the answers

What is the action of Atractyloside on the adenine nucleotide transporter?

It binds to the outward-facing portion of the transporter. Signup and view all the answers

Which of the following statements correctly differentiates inhibitors of the ETC from uncouplers of oxidative phosphorylation?

Uncouplers increase oxygen consumption while inhibitors decrease it. Signup and view all the answers

How does thermogenin function in brown adipose tissue?

It uncouples the H+ gradient from ATP synthesis to generate heat. Signup and view all the answers

What role do ionophores play in cellular respiration?

They form channels or act as mobile carriers for ions. Signup and view all the answers

What is the P/O ratio, and what does it represent in oxidative phosphorylation?

It measures the efficiency of ATP production relative to oxygen consumption. Signup and view all the answers

Which shuttle system synthesizes more ATP from cytoplasmic NADH?

Glycerophosphate shuttle produces 2 ATP per NADH oxidized. Signup and view all the answers

What effect do inhibitors of the electron transport chain have on ATP synthesis?

They decrease ATP synthesis by blocking electron transfer. Signup and view all the answers

What is characteristic of uncouplers compared to inhibitors of the ETC?

Uncouplers disrupt membrane gradients, increasing electron transport. Signup and view all the answers