Biological molecules

• Monomer


  Smaller units which can create larger molecules
• Polymer

  Long chain of repeating units chemically bonded
• Nucleotide


  DNA, RNA
• Alpha glucose


  • Hydroxyl group below carbon 1
• Beta glucose


  • Hydroxyl group above carbon 1
• Chemical tests can be used to identify carbohydrates, proteins, and lipids
• Starch test


  Add iodine - orange to blue-black
• Reducing sugar test


  Benedict's and heat turns blue to brick red
• Non-reducing sugar test(sucrose)

  1. Benedict's test - stays blue

  2. Add acid and boil (hydrolysis)

  3. Add alkali to neutralise

  4. should turn from blue to brick red
• Protein test

  Biuret turns blue to purple
• Lipid test


  Dissolve in ethanol add distilled water and shake - forms emulsion
• Disaccharide


  Made of 2 monosaccharides joined by condensation reaction, forming a glycosidic bond
• Disaccharides


  • Glucose + glucose = maltose + water
  • Glucose + fructose = sucrose + water
  • Glucose + galactose = lactose + water
• Starch


  • Monomer is Alpha Glucose
  • Amylose 1-4 glycosidic- long straight chain
  • Amylopectin 1-6 glycosidic bonds - branched-Increases SA for rapid hydrolysis of glycosidic bonds for glucose release for respiration
  • Coiled - more compact can store more
  • Insoluble no effect on water potential
• Cellulose


  • Beta-1,4 glycosidic bonds
  • Long straight chain with many hydrogen bonds that form microfibrills which provide strength
  • Each alternate glucose rotated 180 degrees
• Glycogen


  • Alpha-1,6 glycosidic bonds
  • Branched structure - Rapid hydrolysis, high surface area for storage in liver and muscle cells
  • insoluble so won't effect the water potential
• Amylase in pancreas produces maltose, maltase in small intestine produces glucose
• condensation reaction

  Joining together of molecule through removing water
• hydrolysis reaction


  Breaking bonds between molecules by the addition of water
• Use of Colorimeter to produce qualitative results

  Make standard solution with known concentrations

  record absorbency levels

  plot calibration curve absorbency y axis conc x axis

  record absorbance of unknown sample

  use calibration to read off conc
• Producing quantitative data

  Do a food test

  Filter, dry and weigh mass of percipitate