Key Questions 2

• Monomer

  A single molecule that makes up larger molecules
• Polymer


  A long chain of repeating units called monomers
• Amino acid


  The type of monomer that makes up a protein
• Condensation reaction


  The type of reaction where amino acids are joined together
• Water


  The molecule that is always formed in a condensation reaction
• Peptide bond


  The bond that is formed between amino acids after a condensation reaction
• Dipeptide


  The name of a molecule formed when two amino acids join together
• Polypeptide


  Three or more amino acids joined by peptide bonds. Most polypeptides contain 100s-1000s of amino acids
• Levels of protein structure

  • Primary
  • Secondary
  • Tertiary
  • Quaternary
• Primary structure


  The sequence/order of amino acids
• Peptide bonds


  The bonds found in the primary sequence of a polypeptide
• Secondary structure


  The first folding of the polypeptide chain either into alpha helices or beta pleated sheets
• Alpha helix


  A coiling of the polypeptide chain caused by hydrogen bonding between amino acids
• Beta pleated sheet


  A folding of the polypeptide chain caused by hydrogen bonding between amino acids
• Hydrogen bonding


  The type of bond found in the secondary structure
• Tertiary structure


  Folding of a polypeptide chain in a 3D shape
• Bonds in tertiary structure

  Hydrogen, ionic, disulphide
• Quaternary structure


  Two or more polypeptide chains
• Types of proteins


  • Globular
  • Fibrous
• Globular protein


  A spherical shaped protein
• Metabolic reactions


  All of the reactions inside an organism
• Anabolic reactions


  A reaction in which a larger molecule is built up from smaller molecules
• Catabolic reactions


  A reaction in which a larger molecule is broken down into smaller molecules
• Enzyme


  A catalyst that speeds up biological reactions
• Activation energy


  The energy needed to start a reaction
• Lock and key model


  The complementary substrate fits exactly into the active site of the enzyme
• Induced fit model


  The theory that the active site of an enzyme changes shape as the complementary substrate binds to it. This is so that it can fit exactly to form an enzyme-substrate complex
• Active site


  Where on the enzyme the substrate binds
• Enzyme-substrate complex


  The structure formed when an enzyme binds to a substrate
• Complementary


  The shape of the active site compared to the substrate
• Tertiary structure


  The level of protein structure that defines the shape of the active site
• Enzyme specificity


  Enzymes only work with one substrate. They are specific to that molecule
• Active site shape


  What makes an enzyme specific - the shape of the active site will only allow one substrate to fit
• Enzyme-substrate complex formation


  The substrate is converted into products
• Factors affecting enzyme-controlled reactions

  • Temperature, pH, enzyme concentration and substrate concentration
• Competitive inhibitor


  They have a similar shape to the substrate, so compete with the substrate for the active site
• Non-competitive inhibitor


  A non-competitive inhibitor binds to an area of the enzyme which is not the active site (allosteric). It alters the shape of the protein and so the substrate can't fit in the active site anymore
• Types of cells


  • Prokaryotic
  • Eukaryotic
• An animal cell is eukaryotic
• A plant cell is eukaryotic