biochem week 8 part 2

Which molecule serves as an allosteric activator in metabolic processes?

a) ATP b) ADP c) NADH d) FADH₂
Correct Answer: a) ATP - ATP is known to activate metabolic processes by serving as an allosteric regulator.

What role does ATP play as a metabolic regulator when in excess?

a) Activates metabolic pathways b) Inhibits metabolic pathways c) No effect on metabolism d) Converts to ADP
Correct Answer: b) Inhibits metabolic pathways - Excess ATP signals to the cell to reduce activity in certain metabolic pathways.

Which cycle is primarily responsible for ATP production?

a) Glycolysis b) Citric Acid Cycle c) Beta-oxidation d) Glycogenesis
Correct Answer: b) Citric Acid Cycle - The citric acid cycle is critical in generating ATP through oxidative phosphorylation.

For every complete turn of the citric acid cycle, how many ATPs are generated?

a) 2 ATP b) 4 ATP c) 6 ATP d) 10 ATP
Correct Answer: d) 10 ATP - Each turn of the citric acid cycle produces a total of 10 ATP equivalents.

Which enzyme complex is regulated by phosphorylation status?

a) Glycogen Synthase b) PDH Complex c) Pyruvate Kinase d) Aldolase
Correct Answer: b) PDH Complex - The PDH complex activity is highly influenced by its phosphorylation state.

In what energy charge condition is the PDH complex inhibited?

a) Low Energy Charge b) High Energy Charge c) No Energy Charge d) Variable Energy Charge
Correct Answer: b) High Energy Charge - High energy charge activates PDH kinase, inhibiting PDH activity.

Which metabolic pathway is activated at a low energy charge?

a) Ketogenesis b) Gluconeogenesis c) Glycolysis d) Lipolysis
Correct Answer: c) Glycolysis - At low energy charge, glycolytic pathways are activated to enhance ATP production.

What is the main function of Pyruvate Carboxylase?

a) Produce lactate b) Convert pyruvate to acetyl CoA c) Replenish oxaloacetate d) Generate ATP
Correct Answer: c) Replenish oxaloacetate - Pyruvate Carboxylase helps to maintain oxaloacetate levels for the citric acid cycle.

What effect does high energy charge have on glycolysis?

a) Activates glycolysis b) Inhibits glycolysis c) No effect d) Activates gluconeogenesis
Correct Answer: b) Inhibits glycolysis - High energy levels lead to decreased activity in glycolysis.

What symptom is indicative of PDH complex deficiency?

a) Increased insulin production b) Elevated pyruvate levels c) Enhanced ATP synthesis d) Increased glucose metabolism
Correct Answer: b) Elevated pyruvate levels - PDH deficiency leads to impaired conversion of pyruvate to acetyl CoA, resulting in excess pyruvate.

What is produced via substrate-level phosphorylation in the citric acid cycle?

a) NADH b) FADH₂ c) ATP d) Lactate
Correct Answer: c) ATP - ATP can be directly produced in the citric acid cycle through substrate-level phosphorylation.

How does high acetyl CoA influence Pyruvate Carboxylase?

a) Inhibits it b) Activates it c) Has no effect d) Converts it to another enzyme
Correct Answer: b) Activates it - High levels of acetyl CoA stimulate Pyruvate Carboxylase to replenish oxaloacetate.

Which molecule is NOT produced during glycolysis?

a) ATP b) NADH c) FADH₂ d) Pyruvate
Correct Answer: c) FADH₂ - FADH₂ is not produced during glycolysis; it is involved in the citric acid cycle.

When oxygen is limited, cells may rely heavily on what process?

a) Anaerobic glycolysis b) Aerobic respiration c) Citric acid cycle d) Fatty acid oxidation
Correct Answer: a) Anaerobic glycolysis - In hypoxic conditions, cells shift to anaerobic glycolysis which leads to lactate production.

What roles do NADH and FADH₂ play in ATP production?

a) Provide direct energy b) Carry electrons to the electron transport chain c) Inhibit metabolic pathways d) Both a and c
Correct Answer: b) Carry electrons to the electron transport chain - NADH and FADH₂ help transfer electrons for ATP synthesis via oxidative phosphorylation.

How does pyruvate convert to acetyl CoA?

a) Through PDH complex activity b) By ATP directly c) Through glycolysis alone d) By mitochondrial transfer
Correct Answer: a) Through PDH complex activity - Pyruvate is converted to acetyl CoA through the action of the PDH complex.

What would likely occur at low energy charge?

a) Catabolic pathways activated b) Anabolic pathways activated c) Increased ATP levels d) Decreased metabolic rate
Correct Answer: a) Catabolic pathways activated - Low energy charge promotes catabolic processes to bolster ATP production.

What is a consequence of PDH complex dysfunction?

a) Increased glucose production b) Elevated pyruvate and lactate levels c) Enhanced aerobic metabolism d) Decreased fatty acid synthesis
Correct Answer: b) Elevated pyruvate and lactate levels - Dysfunction of the PDH complex leads to an accumulation of pyruvate that gets converted to lactate.

Which complex is inhibited at high levels of ATP?

a) PDH complex b) Pyruvate kinase c) Citric acid cycle enzymes d) Fructokinase
Correct Answer: a) PDH complex - High ATP levels signal inhibition of the PDH complex similar to the citric acid cycle.

What effect does excess ATP have on metabolic pathways?

a) Stimulates all metabolic pathways b) Inhibits specific metabolic pathways c) Increases glycolysis d) Has no effect on energy metabolism
Correct Answer: b) Inhibits specific metabolic pathways - Excess ATP indicates sufficient energy, resulting in reduced metabolic activity in certain pathways.