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Difficulty: MediumGaseous Exchange and Cellular Respiration

Match each biochemical component of cellular respiration with its specific functional role in eukaryotic cells.

  • OxaloacetateFour-carbon acceptor molecule that combines with acetyl-CoA to initiate the citric acid cycle
  • Cytochrome cMobile electron carrier shuttling electrons between Complex III and Complex IV in the inner mitochondrial membrane
  • NAD+\text{NAD}^+Coenzyme that acts as an oxidizing agent by accepting electrons and hydrogen during catabolic steps
  • PyruvateThree-carbon glycolytic end-product transported into the mitochondrion for oxidation

Answer

Oxaloacetate matches the four-carbon acceptor molecule that combines with acetyl-CoA; Cytochrome c matches the mobile electron carrier shuttling electrons between Complex III and Complex IV; NAD+ matches the coenzyme that acts as an oxidizing agent by accepting electrons; Pyruvate matches the three-carbon glycolytic end-product.
Oxaloacetate acts as the 4-carbon acceptor molecule for acetyl-CoA in the citric acid cycle; Cytochrome c serves as a mobile electron shuttling protein on the inner mitochondrial membrane; NAD+ is an electron-accepting coenzyme reduced to NADH during oxidative breakdown steps; Pyruvate is the 3-carbon output of glycolysis transported into mitochondria.

Step-by-Step Solution

1
Identify the role of Oxaloacetate in respiration
Oxaloacetate is a 44-carbon molecule in the matrix.
It binds acetyl-CoA to regenerate citrate, continuing the cyclic pathway of the Krebs cycle.
2
Identify the role of Cytochrome c in respiration
Cytochrome c is an electron carrier protein.
It shuttles electrons along the cristae membrane specifically from Complex III to Complex IV in the electron transport chain.
3
Identify the role of NAD+ in respiration
NAD+\text{NAD}^+ functions as an electron acceptor/oxidizing agent.
It picks up high-energy electrons and protons during dehydrogenation reactions in glycolysis, link reaction, and Krebs cycle.
4
Identify the role of Pyruvate in respiration
Pyruvate is the end-product of cytoplasm-localized glycolysis.
Glucose (66 carbons) is broken down into two 33-carbon pyruvate molecules before aerobic entry into the mitochondrion.

Key Concept

Biochemical intermediates and electron transport components of cellular respiration
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Topics

Gaseous Exchange and Cellular Respiration

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