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Cellular Respiration and Metabolism

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  • Stages of glucose metabolism

    1) Glycolysis: partial breakdown of glucose producing ATP and electron carriers.
    2) Pyruvate oxidation: conversion of pyruvate to Acetyl-CoA.
    3) Citric acid cycle: full breakdown producing ATP and electron carriers.

  • Overall cellular respiration reaction

    \(\mathrm{C_6H_{12}O_6 + 6 O_2 \rightarrow 6 CO_2 + 6 H_2O + energy}\)

  • Difference between oxidation and reduction

    Oxidation is loss of electrons; Reduction is gain of electrons.

  • Role of NADH and FADH2 in cellular respiration

    They carry high-energy electrons from glycolysis, pyruvate oxidation, and citric acid cycle to the electron transport chain.

  • Location of glycolysis

    Occurs in the cytoplasm of the cell.

  • Location of pyruvate oxidation and citric acid cycle

    Both occur in the mitochondrial matrix.

  • Net ATP gain from glycolysis

    2 ATP molecules are produced as net gain per glucose molecule.

  • Products of glycolysis

    2 pyruvate, 2 NADH, and 2 net ATP molecules per glucose.

  • Pyruvate oxidation products per glucose

    2 Acetyl-CoA, 2 NADH, and 2 CO2 molecules.

  • Citric acid cycle key features

    Starts and ends with oxaloacetate (4C), produces CO2, NADH, FADH2, and ATP.

  • Carbon flow during glucose metabolism

    Glucose (6C) → 2 Pyruvate (3C each) → 2 Acetyl-CoA (2C each) + CO2 → CO2 in citric acid cycle.

  • Energy carriers produced in citric acid cycle

    NADH, FADH2, and ATP are produced to store energy.

  • Function of electron transport chain

    Uses electrons from NADH and FADH2 to create a proton gradient that drives ATP synthesis.

  • Difference between substrate-level phosphorylation and oxidative phosphorylation

    Substrate-level phosphorylation directly forms ATP during glycolysis and citric acid cycle; oxidative phosphorylation uses the electron transport chain and chemiosmosis.

  • Role of oxygen in cellular respiration

    Oxygen acts as the final electron acceptor in the electron transport chain, forming water.

  • Energy yield from one glucose molecule

    Approximately 30-34 ATP molecules are produced from complete oxidation of one glucose.

  • Difference between autotrophs and heterotrophs

    Autotrophs use inorganic carbon (CO2) and energy from sunlight or chemicals; heterotrophs consume organic compounds for carbon and energy.

  • Photosynthesis vs cellular respiration

    Photosynthesis converts CO2 and H2O into glucose and O2 using light energy; cellular respiration breaks down glucose and O2 to produce CO2, H2O, and ATP.

  • Role of NAD+ in metabolism

    NAD+ is an electron carrier that is reduced to NADH during glycolysis, pyruvate oxidation, and citric acid cycle.

  • What is substrate-level phosphorylation?

    Direct synthesis of ATP by transferring a phosphate group to ADP from a phosphorylated intermediate.