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General Biology I - Cellular Respiration and Fermentation

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  • Overall chemical equation for cellular respiration

    Glucose and oxygen are converted into carbon dioxide, water, and energy (ATP).

    Equation: \(\mathrm{C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + ATP}\)

  • Why does the human body need energy?

    Energy is required for cellular processes such as growth, repair, movement, and maintaining homeostasis.

  • What is a redox reaction?

    A redox reaction involves the transfer of electrons where oxidation is loss of electrons and reduction is gain of electrons.

  • Role of dehydrogenase in cellular respiration

    Dehydrogenase enzymes remove electrons (and hydrogen) from substrates, facilitating redox reactions.

  • Role of NAD+ in cellular respiration

    NAD+ acts as an electron carrier, accepting electrons to become NADH during oxidation reactions.

  • Role of the electron transport chain (ETC)

    The ETC transfers electrons through protein complexes, creating a proton gradient used to produce ATP.

  • Role of oxygen in cellular respiration

    Oxygen is the final electron acceptor in the ETC, combining with electrons and protons to form water.

  • Stages of cellular respiration and their locations

    Glycolysis: cytoplasm; Citric acid cycle: mitochondrial matrix; Oxidative phosphorylation: inner mitochondrial membrane.

  • Energy yield and phosphorylation type in glycolysis

    Produces 2 ATP by substrate-level phosphorylation and 2 NADH per glucose molecule.

  • Energy yield and phosphorylation type in citric acid cycle

    Produces 2 ATP by substrate-level phosphorylation, plus NADH and FADH2 per glucose.

  • Energy yield and phosphorylation type in oxidative phosphorylation

    Produces about 26-28 ATP by chemiosmosis using the proton gradient.

  • Total possible ATP yield per glucose molecule

    Approximately 30-32 ATP molecules can be produced from one glucose molecule.

  • Compare alcohol fermentation and lactic acid fermentation

    Both regenerate NAD+ from NADH to allow glycolysis to continue. Alcohol fermentation produces ethanol and CO2; lactic acid fermentation produces lactate.

  • How are carbohydrates, fats, and proteins used as fuel?

    All can be broken down into molecules entering cellular respiration; fats yield more ATP per gram due to more energy-rich bonds.

  • Why does fat yield more ATP than starch or protein?

    Fats have more C-H bonds which store more energy, resulting in higher ATP yield per gram.

  • How are nutrients used in biosynthesis?

    Nutrients provide carbon skeletons and energy for building macromolecules like proteins, lipids, and nucleic acids.

  • Definition of acetyl CoA

    Acetyl CoA is a molecule that delivers acetyl groups to the citric acid cycle for energy production.

  • What is ATP synthase?

    ATP synthase is an enzyme that synthesizes ATP using the proton gradient during oxidative phosphorylation.

  • What is chemiosmosis?

    Chemiosmosis is the process of ATP generation using energy from a proton gradient across a membrane.

  • What is glycolysis?

    Glycolysis is the breakdown of glucose into pyruvate, producing ATP and NADH in the cytoplasm.

  • What is pyruvate oxidation?

    Pyruvate oxidation converts pyruvate into acetyl CoA, releasing CO2 and producing NADH in mitochondria.

  • What is substrate-level phosphorylation?

    Substrate-level phosphorylation is the direct synthesis of ATP by transferring a phosphate group to ADP from a substrate molecule.