Topic 1 Chemical Reactions in Metabolic Processes

Question 1

• Concentration of reactants and products determine which way reaction will go
• When reaction in equilibrium, the rate of formation of products and reactants is equal and there is 0 net production
• Anabolic reactions: chemical reactions in which small molecules are assembled into larger molecules
• Catabolic process: when large molecules are broken down into small molecules

Answer 1

Characteristics on Chemical Reactions

Question 2

• Enzymes remain unchanged during reaction, varying functions based on pH and temp, have active site that binds substrates via induced fit

Answer 2

Enzyme Functions

Question 3

• ATP is a common source of activation energy
• Stores potential energy in the form of chemical energy
• New ATP is formed via phosphorylation

Answer 3

Role of ATP

Question 4

• ADP and phosphate come together using energy from an energy rich molecule like glucose

Answer 4

Phosphorylation

Question 5

• Can be regulated using the following functions
  1. KM: Michaelis constant and represented the substrate concentration at which the rate of reaction is half of the max velocity of the enzyme, or VMAX
  2. Allosteric enzymes: have both an active site for substrate binding and an allosteric site for the binding of an allosteric effector
  3. Competitive inhibition: a substance that mimics the substrate and inhibits the enzyme by binding at the active site. This can be overcome by increasing substrate concentration. KM raised by VMAX is not.
  4. Noncompetitive inhibition: substance inhibits enzyme by binding elsewhere than the active site, allowing the substrate to still bind, but the reaction is prevented from completing. KM is unchanged but VMAX is lowered.
  5. Uncompetitive/Anti-competitive inhibition: occurs when an enzyme inhibitor binds only to the formed enzyme substrate (ES) complex, preventing formation of product.
• KM inversely represents binding affinity: a small KM indicated that an enzyme only requires a small amount of substrate to become saturated. The maximum velocity, VMAX, is reached at relatively low substrate concentrations. A large KM indicated the need for high substrate concentrations to achieve maximum reaction velocity.
• Relating back to binding affinity, a higher KM equates to worse substrate binding, while a lowered KM equals better substrate binding.
  6. Cooperativity: occurs where an enzyme becomes more receptive to additional substrate molecules after one substrate molecule binds to the active site

Answer 5

Regulation of Enzymes