3.4 - Food as Fuel

• What do gasoline and glucose have in common?

  • both have an abundance of Carbon-Hydrogen Bonds
  • these bonds hold a large amount of Potential Energy
• The farther away an electron is from the nucleus of an atom, the MORE POTENTIAL ENERGY IT HAS
• Potential Energy - Energy stored in an object due to its position or shape
• When we eat food, chemical reactions occur which release potential energy as kinetic energy
• Energy is released as electrons move closer to the nucleus. Because the electron wants to go near the nucleus.
• Energy is absorbed as electrons move farther away from the nucleus. It requires a lot of energy to remove electrons away from the nucleus.
• How is energy released?

  As electrons in the C-H bonds are pulled toward larger and more electronegative nuclei —> energy is released as the electrons move to a lower energy level
• Oxidation - loss of electrons from atoms
• Reduction - gain of electrons from atoms
• as electrons are exchanged…

  • they may be shared in different arrangements
  • which results in the release of energy
• Electrons move towards the more electronegative atom and ENERGY IS RELEASED
• The body can store energy at each step and increase the efficiency of the reaction (less wasted heat energy is released)
• Reactions within the body need to be controlled and undergo many different steps
• Rapid Combustion - The combustion of a fuel in a short period of time, releasing a lot of energy (possibly soot, carbon monoxide and produce CO2, and H2O
• Enzymes helps to CATALYZE each of the steps needed in controlled oxidation
• Controlled Oxidation - The oxidation of a substance in a controlled environment through various steps, releasing small amounts of energy to produce the CO2 and H2O
• What is this graph an example of?

  Rapid Combustion

  
• What is graph an example of?

  Controlled Oxidation

  
• What do enzymes help with in controlled oxidation?

  Catalysis —> series of controlled reactions with energy stored at each step
• Energy is absorbed by Energy-carrier Molecules

  —> can be used to power other reactions or to make ATP
• Energy Carriers

  • molecules that help store energy released by reactions
  • help to power other reactions
  • aka DEHYDROGENASES - help remove hydrogen atoms and transfer electrons
• Dehydrogenases example

  NAD+ is reduced (gains 2 electrons and a Hydrogen) to form NADH. NADH can be used to power ATP synthesis.
• What is the reduction of NAD+?

  NAD+ + 2e- + H+ —> NADH