7.2.2 Link Reaction and Krebs Cycle

• What is the primary function of the Link Reaction?

  Converts pyruvate to acetyl-CoA
• The Link Reaction converts pyruvate into acetyl-CoA
• The Krebs Cycle generates NADH and FADH2 by breaking down acetyl-CoA.
• What are the main products generated by the Krebs Cycle?

  NADH and FADH2
• The Link Reaction occurs in the mitochondrial matrix.
• Order the processes involved in cellular respiration

  1️⃣ Glycolysis

  2️⃣ Link Reaction

  3️⃣ Krebs Cycle

  4️⃣ Electron Transport Chain
• Which process in cellular respiration is directly connected to the Krebs Cycle?

  Link Reaction
• Carbon dioxide is a byproduct of both the Link Reaction and the Krebs Cycle.
• The Link Reaction and Krebs Cycle both occur in the mitochondrial matrix.
• What is the primary function of the Link Reaction in cellular respiration?

  Converts pyruvate to acetyl-CoA
• The Krebs Cycle generates ATP directly.
• What is the primary function of the Link Reaction?

  Converts pyruvate to acetyl-CoA
• The Krebs Cycle breaks down acetyl-CoA to generate NADH and FADH2.
• Match the process with its primary input:

  Link Reaction ↔️ Pyruvate

  Krebs Cycle ↔️ Acetyl-CoA
• Both the Link Reaction and Krebs Cycle occur in the mitochondrial matrix.
• The mitochondrial matrix provides the necessary enzymes and conditions for the Link Reaction and Krebs Cycle.
• What is the primary role of the Krebs Cycle?

  Generates NADH and FADH2
• The input of the Link Reaction is pyruvate.
• The Krebs Cycle generates ATP directly within the mitochondrial matrix.
• Match the process with its location:

  Link Reaction ↔️ Mitochondrial matrix

  Glycolysis ↔️ Cytoplasm
• Glycolysis occurs in the cytoplasm of the cell.
• What is the role of the Link Reaction in cellular respiration?

  Prepares pyruvate for Krebs Cycle
• Steps of the Link Reaction:

  1️⃣ Decarboxylation of pyruvate

  2️⃣ Oxidation of the remaining molecule

  3️⃣ Acetyl-CoA formation
• Decarboxylation in the Link Reaction produces carbon dioxide.
• Acetyl-CoA is formed when the acetyl group combines with coenzyme A.
• Which enzyme catalyzes the formation of acetyl-CoA in the Link Reaction?

  Pyruvate dehydrogenase
• Pyruvate is decarboxylated during the Link Reaction to produce NADH.

  False
• Steps of the Krebs Cycle:

  1️⃣ Condensation of acetyl-CoA with oxaloacetate

  2️⃣ Isomerization of citrate to isocitrate

  3️⃣ First decarboxylation to form α-ketoglutarate

  4️⃣ Second decarboxylation to form succinyl-CoA

  5️⃣ Substrate-level phosphorylation to generate ATP/GTP

  6️⃣ Oxidation of succinate to fumarate

  7️⃣ Hydration of fumarate to malate

  8️⃣ Regeneration of oxaloacetate
• Match the Krebs Cycle enzyme with its corresponding reaction:

  Citrate synthase ↔️ Forms citrate from acetyl-CoA and oxaloacetate

  Aconitase ↔️ Converts citrate to isocitrate

  Isocitrate dehydrogenase ↔️ Oxidizes isocitrate to α-ketoglutarate

  Malate dehydrogenase ↔️ Regenerates oxaloacetate from malate
• Substrate-level phosphorylation in the Krebs Cycle generates ATP or GTP.
• Succinate is oxidized to form fumarate by the enzyme succinate dehydrogenase.
• Arrange the steps of the Krebs Cycle in the correct order

  1️⃣ Condensation: Acetyl-CoA combines with oxaloacetate to form citrate

  2️⃣ Isomerization: Citrate is converted to isocitrate

  3️⃣ First Decarboxylation: Isocitrate is oxidized to α-ketoglutarate, CO2, and NADH

  4️⃣ Second Decarboxylation: α-ketoglutarate is oxidized to succinyl-CoA, CO2, and NADH

  5️⃣ Substrate-Level Phosphorylation: Succinyl-CoA is converted to succinate, generating ATP or GTP

  6️⃣ Oxidation: Succinate is oxidized to fumarate, producing FADH2

  7️⃣ Hydration: Fumarate is hydrated to form malate

  8️⃣ Regeneration of Oxaloacetate: Malate is oxidized to oxaloacetate, producing NADH
• The Krebs Cycle occurs in the mitochondrial matrix
• What enzyme catalyzes the condensation of acetyl-CoA and oxaloacetate to form citrate?

  Citrate synthase
• What are the outputs of the first decarboxylation step in the Krebs Cycle?

  α-ketoglutarate, CO2, NADH
• Which enzyme catalyzes the second decarboxylation in the Krebs Cycle?

  α-ketoglutarate dehydrogenase complex
• Substrate-level phosphorylation in the Krebs Cycle generates ATP or GTP
• Succinate is oxidized to fumarate, producing FADH2
• What enzyme hydrates fumarate to form malate?

  Fumarase
• What are the two electron carriers generated by the Krebs Cycle that are crucial for oxidative phosphorylation?

  NADH and FADH2