Ch. 6

• Energy: The capacity to do work
• Kinetic energy: the energy of motion

  Potential energy: energy that is stored
• Heat energy: internal motion of particles of matter
• Chemical energy: energy that bonds atoms or ions together
• Entropy: measure of the random motion of molecule
• Free energy (G): amount of energy available to break and subsequently form other chemical bonds
• Endergonic (+G): any reaction that requires an input of energy, positive change in G
• Exergonic (-G): any reaction that releases free energy, negative change in G
• Activation Energy (Ea): energy needed for most reactions to get started
• • Enzyme: a biological catalyst that is usually a protein
  • Catalyst: increase the speed of a reaction
  • Substrate: molecule that will undergo a reaction
• Catabolism: type of metabolism that breaks down molecules, releases energy
• Activation site: region of the enzyme that binds to the substrate
• Multi-enzyme complexes: enzymes that can be associated together
• Inhibitors: substance that binds to an enzyme and decreases its activity

  1. Competitive inhibitors: complete with the substrate for the same active site
  2. Noncompetitive inhibitors: bind to the enzyme in a location other than the active site (allosteric sites)
• ATP (adenosine triphosphate): molecule composed of ribose, adenine, and a triphosphate group that is used as the main currency of cellular energy
• Metabolism: the total of all chemical reactions carried out by an organism to maintain life

  • Anabolism: type of metabolism that builds molecules, uses energy
  • Catabolism: type of metabolism that breaks down molecules, releases energy
• Feedback inhibition: when a cell has enough product, it inhibits pathway by binding to site on the first enzyme of the pathway
• (Energy Concepts 5/10)

  • All forms of energy can be converted to heat energy
  • Heat energy is measured by temperature
  • The faster the particles move, the more heat energy is present
  • When chemical bonds are broken, energy is released
  • Energy flows into the world from the sun
• (Energy Concepts 10/10)

  • Plants, algae, and some bacteria capture energy through photosynthesis
  • Energy is stored as potential energy in chemical bonds
  • Heat is the most disorganized form of energy
  • Some energy is lost as heat into the environment for each chemical reaction
  • Every energy exchange increases the amount of entropy
• Thermodynamics

  • First Law of Thermodynamics:
  • energy cannot be created or destroyed, it can only change form
  • Second Law of Thermodynamics:
  • in spontaneous processes, entropy (disorder) increases
  • Third Law of Thermodynamics:
  • entropy of a system goes to a constant as the temperature gets down to absolute zero
• Enzymes 4/8

  • Enzymes are not changed or consumed in the reaction
  • Binding to a substrate causes the enzyme to change shape, produces a better fit between molecules
  • 3D shape provides active sites for specific substrates to bind and form enzyme-substrate complex
  • Enzymes are located in cytoplasm, plasma membrane, and organelles
• Enzyme 8/8

  • Benefits of the multi-enzyme complex

  1. Product of one reaction can be directly delivered to the next enzyme
  2. The possibility of unwanted side reactions is eliminated
  3. All of the reactions can be controlled as a unit

  • Factors that affect enzyme activity:
  • temperature, pH, salt concentration, inhibitors, activators
  • There are two types of enzyme inhibitors; competitive inhibitors and non-competitive inhibitors
  • Enzymes can be assisted by additional chemicals like cofactors and coenzymes which make the active site correct for the substrate
• ATP 5/9

  • ATP is the main cell energy currency
  • Energy in ATP is stored in a triphosphate group
  • Energy is released when the phosphate bonds are broken
  • Cells use ATP to drive endergonic reactions
  • ADP: adenosine diphosphate
• ATP (9/9)

  • ATP has a low activation energy, bonds break easily
  • When the bonds break, it transfers a lot of energy
  • Break off a phosphate bond to form ADP
  • ATP is for long-term energy storage
• Metabolism and Biochemical Pathways (1/4)

  • Metabolism: the total of all chemical reactions carried out by an organism to maintain life
  • Anabolism: building molecules, uses energy
  • Catabolism: breaking down, releases energy
• Metabolism and Biochemical Pathways (4/4)

  • Many reactions occur in sequences; biochemical pathways
  • Must be coordinated and regulated
  • Cell temporarily shuts down biological pathways when their products are not needed