BIOL.1406 Ch. 6

• Differentiate kinetic energy from potential energy

  Kinetic energy is the energy of motion vs. potential energy is stored energy
• Second law of thermodynamics


  A statement concerning the transformation of potential energy into heat; it says that disorder (entropy) is continually increasing in the universe as energy changes occur, so disorder is more likely than order
• What is thermodynamics?

  The study of transformations of energy, using heat as the most convenient form of measurement of energy.
• Energy


  Defined as the capacity to do work
• Potential energy


  • Objects that have the capacity to move but are not moving have potential energy
• What is redox reaction?

  A type of paired reaction in living systems in which electrons lost from one atom (oxidation) are gained by another atom (reduction).
• When plants are eaten by animals, the chemical energy is transformed to

  Mechanical energy
• When animals walk, move or run, the chemical energy is transformed to

  Mechanical energy
• If G < 0, what does it mean?

  - spontaneous

  - reactants have more free energy than the products

  - “downhill” reaction

  -exergonic
• Differentiate exergonic from endergonic reaction

  • Endergonic- describes a chemical reaction in which the products contain more energy than the reactants
  • Exergonic- describes a chemical reaction in which the products contain less free energy than the reactants
• Components of ATP

  • Adenine, Ribose, Three phosphate groups
• First law of thermodynamics


  Energy cannot be created or destroyed, but can only undergo conversion from one form to another; thus, the amount of energy in the universe is unchangeable
• Entropy


  A measure of the randomness or disorder of a system; a measure of how much energy in a system has become so dispersed (usually as evenly distributed heat) that it is no longer available to do work
• Two forms of energy

  • Kinetic energy
  • Potential energy
• Light energy from the sun is transformed by plants to

  Chemical energy
• Kinetic energy


  • Objects that are in motion
• What is Free energy?

  • Energy available to do work.
  • A living system’s Free energy (G)is energy that can do work when temperature and pressure are uniform, as in a living cell.
• What is released to the environment when energy is transformed from one form to another?
• If G > 0, what does it mean?

  - not spontaneous

  - reactants have less free energy than the products

  - “uphill” reaction

  -endergonic
• ATP

  Adenosine Triphosphate (ATP)- a precursor for RNA and also the energy currency for the cell
• Hydrolysis of ATP

  When one phosphate of ATP is hydrolyzed, high energy bonds are released
• ATP is used to perform cellular work
• Combustion vs Cell respiration

  Similarities: Both use glucose as fuel, give off heat, need oxygen, and have products of carbon dioxide and water
• ATP


  • A precursor for RNA and the energy currency for the cell
• Enzymes are very specific for the reactants (substrates)
• Activation energy of catalyzed reactions is lower than that of uncatalyzed reactions, making catalyzed reactions occur faster
• Enzymes speed up chemical reactions by orienting substrates correctly and straining substrate bonds
• Naming enzymes

  Enzymes are named by adding a suffix "-ase" to the root name of the substrate molecule they act upon
• Apple slices turn brown after being cut due to enzymatic browning, which can be delayed or eliminated by processes like adding lemon juice or refrigeration
• Enzyme


  A catalyst that drives reaction rates forward
• Factors affecting rate of enzyme activity

  • Temperature
  • pH
  • Concentration of enzyme
  • Concentration of substrate
• Exothermic reaction


  Describes a chemical reaction in which the products contain less free energy than the reactants, so that free energy is released in the reaction
• High energy bonds are released in the hydrolysis of ATP
• Enzymes are not consumed after the reaction
• Types of cellular work

  • Mechanical
  • Transport
  • Chemical
• Components of ATP

  • 5-carbon sugar, ribose
  • Adenine
  • A chain of three phosphates
• Catalyst


  Chemical agent that speeds up a reaction without being consumed by the reaction
• Combustion vs Cell respiration

  Differences: Combustion is external, while cell respiration is internal
• Activation energy


  Initial energy needed to start a chemical reaction
• Catalytic cycle of enzyme


  1. Substrate binds to the active site of the enzyme

  2. Enzyme-substrate complex is formed

  3. Stress on the substrate bond causes it to break

  4. Products are released and the enzyme is free to bind other substrates