Biological molecules

• Elements that make up carbohydrates

  Carbon, Hydrogen and Oxygen
• Elements that make up lipids


  Carbon, Hydrogen and Oxygen
• Elements that make up protein

  Nitrogen, Hydrogen, Carbon and Oxygen
• What is a substrate?

  The molecule upon which an enzyme acts
• Most common subunit of carbohydrates

  Glucose
• What are lipids made up of

  Fatty Acids and Glycerol
• What subunit are proteins made up of

  Amino Acids
• Disaccharide


  A sugar formed when two simple sugar molecules (monosaccharides) are joined by glycosidic linkage
• Monosaccharide


  The simplest form of a sugar molecule (i.e. glucose)
• Enzyme


  A biological catalyst in metabolic reactions
• Catalyst


  Something that speeds up reactions without being changed themselves
• Why are enzymes 'specific in their action'?

  They can only break down certain substrates down
• How does the active site make enzymes specific in their action?

  It has a specific shape, that will only break a certain substrate down
• Product


  Smaller chains of molecules that have been broken up
• Anabolic enzymes


  Build up molecules
• Catabolic enzymes


  Break down molecules
• What causes enzymes to denature?

  Enzymes have a very specific shape. High temperatures/ pHs above their optimum change the bonds between amino acids in enzymes, changing their shape. This means that substrates will not fit the enzyme's active site.
• Graph of enzymes rate of reaction against temperature

  Enzymes efficiency increases up to a point, called the optimum temperature. Substrates have more KE, so collide with enzymes often. After this temperature, enzyme efficiency falls rapidly because enzymes denature

  
• Average optimum temperature for enzymes in the human body

  37 °C
• Test for starch


  The food sample is placed on a spotting tile. A few drops of iodine are added, and the colour change is recorder.
• Iodine goes from ____ to _____ if starch is present

  orangey brown, blue black
• Test for lipids


  The food sample is added to a test tube. Next ethanol is added, and the test tube is shaken. When distilled water is added, an emulsion will form if fat is present.
• Ethanol goes from ____ to _____ if fat is present

  clear, cloudy
• Test for protein


  The food sample is liquidised using a pestle and mortar and added to a test tube. A few drops of Biuret solution are added. The colour change is recorded.
• Biuret's solution goes from ____ to _____ if protein is present

  blue, purple
• Test for glucose


  Blue Benedict's solution is added to a test tube. The food sample is added to the test tube, which is added to boiling water for 3 minutes. The colour change is recorded.
• Blue Benedict's solution goes from ____ to _____ if glucose is present


  blue, green/ yellow/ orange/ brick red