Chapter+8.pptx

Metabolism

• Energetics: The flow of energy through a system.
• Bioenergetics: The flow of energy through a biological system.
  • Metabolism is the totality of an organism’s chemical reactions.

Organization of Metabolic Pathways

• A metabolic pathway begins with a specific molecule and ends with a product
• Each step is catalyzed by a specific enzyme

• Catabolic pathways release energy by breaking down complex molecules into simpler compounds
  • Breakdown of Hydrogen Peroxide by Catalase: H2O2 → H2O + O2
• Anabolic pathways utilize energy to build complex molecules from simpler ones
  • Creation of Hydrogen Peroxide: H2O + O2 → H2O2

Forms of Energy

• Energy is the capacity to cause change
• Energy exists in various forms, some of which can perform work
  • Potential energy: The energy at rest
  • Kinetic energy: The energy used for work/motion
    • Heat (thermal energy) is associated with random movement of atoms or molecules
    • Chemical energy is energy associated with chemical reaction
• Energy can be converted from one form to another - many chemical reactions release of heat.

The Laws of Energy Transformation

• Thermodynamics is the study of energy transformations

  First Law of Thermodynamics

  • First law of thermodynamics = energy of the universe is constant
    • Energy can be transferred and transformed, but it cannot be created or destroyed
  • The first law is also called the principle of conservation of energy

  Second Law of Thermodynamics

  • Every energy transfer or transformation increases the entropy (disorder) of the universe
  • During every energy transfer or transformation, some energy is unusable, and is often lost as heat

Biological Order and Disorder

• Cells create ordered structures from less ordered materials – anabolic reaction; = input of energy.
• Cells also replace ordered forms of matter and energy with less ordered forms – catabolic reactions; = the release of energy.