TCA Cycle 1

The video explores the TCA cycle, focusing on reactions up to succinyl CoA production. It distinguishes between pathways and cycles, emphasizing the regeneration of citrate. Key reactions include those catalyzed by citrate synthase, aconitase, isocitrate dehydrogenase, and alpha-ketoglutarate dehydrogenase. The video highlights the allosteric regulation of these enzymes and discusses the energy yield and carbon tracking within the cycle.

What is the primary distinction between a pathway and a cycle in biochemical terms?

• A cycle is always linear.

• A pathway is always circular.

• A pathway regenerates its starting substrate.

• A cycle regenerates its starting substrate.

Which enzyme is the first allosteric enzyme in the TCA cycle?

• Alpha-ketoglutarate dehydrogenase

• Citrate synthase

• Isocitrate dehydrogenase

• Aconitase

What is the intermediate formed during the reaction catalyzed by aconitase?

• Isocitrate

• Cis-aconitate

• Alpha-ketoglutarate

• Citrate

Which molecule is produced alongside NADH in the reaction catalyzed by isocitrate dehydrogenase?

• Water

• FADH2

• CO2

• ATP

What is the product formed when isocitrate is dehydrogenated?

• Citrate

• Alpha-ketoglutarate

• Succinyl CoA

• Oxaloacetate

Which enzyme complex in the TCA cycle is similar to the pyruvate dehydrogenase complex?

• Citrate synthase

• Aconitase

• Isocitrate dehydrogenase

• Alpha-ketoglutarate dehydrogenase

What is the main product of the alpha-ketoglutarate dehydrogenase complex reaction?

• Fumarate

• Isocitrate

• Succinyl CoA

• Citrate

What is the term used to describe the highly regulated area of biochemistry involving multiple allosteric enzymes?

• Allosteric corridor

• Regulatory cycle

• Metabolic pathway

• Allosteric pathway

How many NADH molecules are produced up to the formation of succinyl CoA in the TCA cycle?

• Three

• Two

• Four

• One

Which enzyme in the TCA cycle is not regulated allosterically?

• Alpha-ketoglutarate dehydrogenase

• Isocitrate dehydrogenase

• Aconitase

• Citrate synthase