Exam Review

Chapter 8: Enzymes and Metabolism

• Overview of chapter contents:

  • Overview of energy concepts

  • Enzymes and metabolism

• Key Concepts:

  • Chemical Reactions:

  • Definitions of reactants and products in a chemical reaction.

  • Understanding the progression of a chemical reaction from reactants to products.

  • Types of Energy:

  • Potential Energy: Energy stored in an object.

    • Examples:

    • A ball at the top of a cliff.

    • Water reservoir behind a dam.

    • A human being on a bicycle at the top of a hill.

  • Kinetic Energy: Energy of motion.

    • Example:

    • Bicycles coasting down a hill due to gravitational pull - no input of energy required.

• Metabolism:

  • Definition: The set of life-sustaining chemical reactions that allow organisms to convert food into energy.

  • Types of Metabolism in Cells:

  • Catabolism (breaking down molecules)

  • Anabolism (building up molecules)

• Thermodynamics:

  • Two basic laws:

  • First Law of Thermodynamics: Energy cannot be created or destroyed, only transferred or transformed.

  • Second Law of Thermodynamics: In any energy transfer, the degree of disorder (entropy) in the universe increases.

• ATP (Adenosine Triphosphate):

  • Structure:

  • Consists of adenosine, ribose sugar, and three phosphate groups.

  • Function:

  • Primary energy carrier in cells.

  • Energy is stored in the triphosphate part, released when a phosphate group is cleaved to form ADP (Adenosine Diphosphate).

• Enzymes:

  • Definition: Proteins that catalyze biochemical reactions.

  • Regulation of enzyme activity discussed.

Chapter 9: Cellular Respiration

• Overview of cellular respiration processes.

• Metabolic Pathways:

  • Glycolysis and Cellular Respiration as pathways for energy extraction from glucose.

• Redox Reactions:

  • Definition: Reactions involving transfer of electrons between molecules.

  • NAD (Nicotinamide adenine dinucleotide) as an electron carrier in cellular respiration.

  • Note: NAD is becoming popular as a supplement to enhance metabolism, particularly among athletes.

• Role of Oxygen:

  • Acts as the final hydrogen ion acceptor in the electron transport chain (ETC).

  • Combines with hydrogen ions to produce water.

• Processes:

  • Glycolysis: Anaerobic process (occurs without oxygen), breaks down glucose into pyruvate.

  • Main products:

    • 2 ATP molecules

    • 2 NADH

    • 2 Pyruvate

    • CO2 waste is produced.

  • Citric Acid Cycle (Krebs Cycle):

  • Oxaloacetate is regenerated, providing a substrate for the cycle to continue.

  • Main products:

    • NADH, FADH2 (electron carriers), ATP, and CO2 waste.

  • Electron Transport Chain:

  • Most ATP produced here through chemiosmosis.

  • Hydrogen ions flow through ATP synthase, generating ATP.

Chapter 10: Photosynthesis

• Overview of photosynthesis as the process where plant cells convert light energy to chemical energy (carbohydrates).

• Overall Equation of Photosynthesis:

  • ext{CO}2 + ext{H}2 ext{O} + ext{Light Energy}
    ightarrow ext{Glucose} + ext{O}_2

• Carbon Fixation:

  • Definition: The incorporation of CO2 into organic molecules (carbohydrates).

• Light Reactions:

  • Capture solar energy; produce ATP and NADPH; wastes oxygen.

• Calvin Cycle (Dark Reactions):

  • Uses ATP and NADPH to convert CO2 into glucose.

• Importance for Life on Earth:

  • Provides energy for ecosystems, as animals derive energy from plant-produced carbohydrates.

• Key Steps:

  • Light reactions happen in thylakoid membranes, involve photosystems that absorb light.

  • The Calvin Cycle occurs in the stroma, fixing carbon to synthesize glucose.

• Comparison with Cellular Respiration:

  • Similar pathways in energy transformation are noticeable between cellular respiration and photosynthesis.