Enzymes

• What are molecules that bind to enzymes and slow or prevent their activity called?


  Enzyme inhibitors
• What is competitive inhibition in enzyme activity?


  • Similar shape to substrate molecules
  • Compete with substrate for active site
  • No enzyme-substrate (ES) complex formed
• What characterizes non-competitive inhibition?


  • Does not bind to active site
  • Binds to allosteric site
  • Changes active site shape, preventing ES complex formation
• How can the rate of reaction be increased in competitive inhibition?


  By increasing the concentration of substrates
• What happens to the reaction rate in non-competitive inhibition when the substrate concentration increases?


  The reaction rate does not increase
• What do enzymes allow protons to do?


  Go past the energy barrier
• What are the two types of protein structures in aqueous solutions?

  • Globular: soluble, spherical shape due to charged groups attracting water
  • Fibrous: straight chain polypeptides, held by hydrogen bonds, more resistant due to crosslinks and disulfide bridges
• What is the test for proteins called?

  Biuret test
• How is the Biuret test performed?


  1. Place sample in a test tube with sodium hydroxide
  2. Add dilute 0.01M copper (II) sulfate solution
  3. Mix gently; purple indicates peptide bonds present
• What are the monomers and covalent bond types for carbohydrates, proteins, nucleic acids, and lipids?


  • Carbohydrates: Monosaccharides, Glycosidic bond
  • Proteins: Amino Acids, Peptide bond
  • Nucleic Acids: Nucleotides, Phosphodiester bond
  • Lipids: Fatty acids, Ester bond
• What are examples of polymers for carbohydrates, proteins, and nucleic acids?

  • Carbohydrates: Polysaccharides (glycogen, cellulose, starch)
  • Proteins: Polypeptides (enzymes)
  • Nucleic Acids: Polynucleotides (DNA, RNA)
• How do enzymes speed up the rate of reaction?


  By acting as a catalyst to lower activation energy
• What is the structure of enzymes?


  3D tertiary structure globular proteins
• What is the active site of an enzyme made of?


  Some amino acids specific to the substrate
• What models describe how enzymes interact with substrates?


  Lock and Key model and Induced Fit model
• How does the Induced Fit model differ from the Lock and Key model?


  The active site changes shape to fit the substrate in the Induced Fit model
• How do enzymes facilitate reactions at lower temperatures?


  By making bond formation easier or reducing strain to break bonds
• What does temperature represent in relation to molecular energy?


  The general mass of molecular energy
• What happens to the rate of reaction as temperature increases?

  It increases until a denaturation point is reached
• What occurs at the denaturation point of an enzyme?


  Hydrogen bonds can break, affecting enzyme structure
• How does enzyme/substrate concentration affect the rate of reaction?


  Increases the rate as more substrate is available for the active site
• What happens if temperature increases beyond the optimum for enzyme activity?


  The rate of reaction decreases