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Cellular Respiration and Metabolism - General Biology

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Termini in questo insieme (27)

  • What is metabolism?

    Metabolism is the totality of an organism’s chemical reactions, including catabolic and anabolic pathways.

  • Define catabolic and anabolic pathways.

    Catabolic pathways release energy by breaking down complex molecules. Anabolic pathways consume energy to build complex molecules from simpler ones.

  • What is cellular respiration?

    Cellular respiration is a catabolic pathway that breaks down organic molecules to generate ATP, involving aerobic or anaerobic processes.

  • Write the overall chemical equation for aerobic cellular respiration.

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

  • What are redox reactions in cellular respiration?

    Redox reactions transfer electrons between reactants; oxidation is loss of electrons, reduction is gain of electrons.

  • Name the two main electron carriers in cellular respiration.

    NAD+ (nicotinamide adenine dinucleotide) and FAD (flavin adenine dinucleotide) carry electrons to the electron transport chain.

  • List the four stages of cellular respiration.

    1. Glycolysis
    2. Pyruvate oxidation
    3. Citric acid (Krebs) cycle
    4. Oxidative phosphorylation (electron transport and chemiosmosis)

  • Where does glycolysis occur and what does it produce?

    Glycolysis occurs in the cytoplasm and breaks glucose into two pyruvate molecules, producing a net of 2 ATP and 2 NADH.

  • What happens during pyruvate oxidation?

    Pyruvate is transported into the mitochondrion and converted to Acetyl CoA, producing NADH and releasing CO2.

  • What are the products of one turn of the citric acid cycle?

    Each turn produces 1 ATP, 3 NADH, 1 FADH2, and releases 2 CO2 molecules.

  • Where does oxidative phosphorylation occur and what is its role?

    It occurs in the inner mitochondrial membrane and uses the electron transport chain and chemiosmosis to produce most ATP.

  • How does the electron transport chain generate ATP?

    Electrons from NADH and FADH2 pass through protein complexes, releasing energy to pump protons and create a gradient that drives ATP synthase.

  • What is the final electron acceptor in aerobic respiration?

    Oxygen (O2) accepts electrons at the end of the electron transport chain, forming water (H2O).

  • How many ATP molecules are produced per glucose molecule in cellular respiration?

    Approximately 30 to 32 ATP molecules are produced per glucose molecule.

  • What happens to cellular respiration in the absence of oxygen?

    The electron transport chain halts, and glycolysis couples with fermentation to regenerate NAD+ for ATP production.

  • Name two common types of fermentation.

    Alcohol fermentation and lactic acid fermentation are two common types.

  • What is the role of ATP in cellular work?

    ATP provides energy for cellular work by hydrolysis, releasing energy to drive endergonic reactions.

  • Explain energy coupling in cells.

    Energy coupling uses energy released from exergonic reactions to drive endergonic reactions, often mediated by ATP.

  • What is activation energy and how do enzymes affect it?

    Activation energy is the initial energy needed to start a reaction; enzymes lower activation energy to speed up reactions.

  • How do enzymes work with substrates?

    Enzymes bind substrates at the active site, forming an enzyme-substrate complex that stabilizes the transition state and catalyzes the reaction.

  • What is allosteric regulation of enzymes?

    Allosteric regulation involves molecules binding to sites other than the active site to inhibit or activate enzyme activity.

  • What is the difference between competitive and noncompetitive enzyme inhibitors?

    Competitive inhibitors bind the active site; noncompetitive inhibitors bind elsewhere, altering enzyme function.

  • How is cellular respiration regulated?

    Negative feedback controls enzyme activity; high ATP slows respiration, low ATP speeds it up.

  • What is the First Law of Thermodynamics?

    Energy can be transferred and transformed but cannot be created or destroyed.

  • What is the Second Law of Thermodynamics?

    Every energy transfer increases the entropy (disorder) of the universe.

  • Define free energy (G) and its significance in metabolism.

    Free energy (G) is the energy available to do work; reactions with negative ΔG are spontaneous.

  • What is the difference between exergonic and endergonic reactions?

    Exergonic reactions release energy (ΔG < 0); endergonic reactions require energy input (ΔG > 0).