Biological molecules

• Molecule: Subunits:

  Carbohydrates ——> simple sugars

  Proteins ——> Amino acids

  Lipids ——> Fatty acids and glycerol

  Nucleic Acids (DNA, RNA) ——> nucleotides
• Testing for starch:

  Molecule: STARCH

  Reagents: Iodine Solution

  Starting colour: Orange/Brown

  Colour if present: Blue/Black
• Testing for Glucose:

  Molecule: Reducing sugar (glucose)

  Reagents: Benedicts solution

  Starting colour: Light blue

  Colour if present: Brick red (yellow/green if concentration is low)

  Other details: Heat about 80 degrees
• Testing for Protein:

  Molecule: Protein

  Reagents: Biuret solution

  Starting Color: Light blue

  Colour if present: Purple
• Testing for lipids:

  Molecule: Lipids

  Reagents: Water and ethanol

  Starting Colour: Colourless

  Colour if present: White emulsion
• • Enzyme-substrate complex - when the substrate is attached to the enzyme

  
• • Active site - where the substrates bind to the enzyme if they are complementary in shape

  
• Substrates - ions or molecules that are used by enzymes to carry out chemical reactions/substance on which an enzyme acts

  
• • Enzyme - protein catalyst used to speed up a chemical reaction
• What affects the shape of the active site?

  • pH
  • Temperature
• If the active site changes shape we say the enzyme has been DENATURED
• Before optimum:

  Rate of reaction increases

  • Because kinetic energy when heating up so more movement of molecules to cause more collisions and increase in enzyme-substrate complexes
• After optimum conditions:

  Rate of reaction decreases

  • Active sights changes shape and therefore the enzyme denatures
  • Fewer collisions and less enzyme-substrate complexes form
• pH ——> measure of hydrogen ions concentration
• At pHs EITHER above or below the optimum, the change in hydrogen ion concentration causes the active site to change shape and therefore the enzyme denatures
• Substrate concentration - concentration increases until a certain point when there are no more enzymes available to make the reaction quicker