Cellular Respiration

Chapter 1: Intro to Cellular Respiration

  • Definition: Cellular respiration is the process of deriving energy from food.

  • Chemical Equation: 1 molecule of glucose (C6H12O6) reacts with 6 molecules of oxygen to produce 6 molecules of carbon dioxide and 6 molecules of water, releasing energy.

  • Energy Release: The process is exergonic and releases energy, some of which is lost as heat.

Chapter 2: Intro to ATP – Adenosine Triphosphate

  • ATP Function: ATP (adenosine triphosphate) is the energy currency of the cell, necessary for movement and growth.

  • Phosphate Transfer: Energy is stored by converting ADP (adenosine diphosphate) into ATP.

  • Reaction Types:

    • Endergonic reactions require energy to proceed (ATP synthesis).

    • Exergonic reactions release energy (ATP breakdown).

  • Efficiency of ATP: It’s more efficient to use ATP for cellular work than the direct energy from glucose, as ATP releases energy in smaller amounts, reducing heat loss.

  • Analogy: Similar to an engine—small combustion releases energy efficiently, while one large explosion is not practical.

  • ATP Structure: ATP consists of

    • Five-carbon ribose sugar.

    • Nitrogenous base (adenine).

    • Three phosphate groups.

Chapter 3: The 4 Stages of Cellular Respiration

  • Overview of Stages: Cellular respiration consists of 4 stages:

    1. Glycolysis: Splitting of glucose into two molecules of pyruvate.

    2. Pyruvate Oxidation: Conversion of pyruvate into acetyl coenzyme A (Acetyl-CoA).

    3. Krebs Cycle: Acetyl-CoA oxidized into carbon dioxide, producing NADH and FADH2.

    4. Electron Transport Chain: NADH and FADH2 donate electrons to produce ATP.

  • Location of Stages:

    • Glycolysis: Cytosol.

    • Pyruvate Oxidation: Mitochondria.

    • Krebs Cycle: Mitochondrial matrix.

    • Electron Transport Chain: Inner mitochondrial membrane.

Chapter 4: Glycolysis

  • Process of Glycolysis: Converts glucose (6 carbons) into two pyruvate molecules (3 carbons each).

    • Pyruvate structure includes a methyl group, carbonyl group, and carboxylate group.

  • Product of Glycolysis: Produces 2 ATP molecules from ADP.

Chapter 5: Substrate Level Phosphorylation

  • Substrate-Level Phosphorylation: Direct addition of a phosphate group to ADP to form ATP.

  • Oxidative Phosphorylation: Occurs later in the electron transport chain.

  • Key Reactions:

    • Glycolysis: Glucose oxidized to pyruvate (oxidation).

    • NAD+ reduced to NADH.

Chapter 6: Oxidation and Reduction Reactions

  • Definitions:

    • Oxidation Reaction: Oxidation state increases; loss of electrons; gain of oxygen or loss of hydrogen.

    • Reduction Reaction: Oxidation state decreases; gain of electrons; loss of oxygen or gain of hydrogen.

  • Example: Conversion of NAD+ to NADH is a reduction reaction:

    • Gain of hydrogen and electrons.

Chapter 7: Investment and Payoff Phase of Glycolysis

  • Stages of Glycolysis:

    • Investment Phase: First 5 steps, requiring 2 ATP molecules.

    • Payoff Phase: Last 5 steps, producing 4 ATP molecules.

  • Net gain of Glycolysis: 2 ATP molecules per one glucose molecule.

Chapter 8: Enzymes – Kinase and Isomerase

  • Overview of Glycolysis: 10 reactions, producing and consuming ATP.

    • Investment of 2 ATP (steps 1 and 3); Payoff of 4 ATP.

    • 2 NADH produced as glucose splits into 2 pyruvate molecules.

Chapter 9: Pyruvate Oxidation into Acetyl-CoA

  • Enzymes Used: Different enzymes facilitate the conversion process of pyruvate to acetyl-CoA.