Biological molecules

• What monomer's make up maltose?

  glucose+glucose
• what monomers make up sucrose?

  glucose+fructose
• what monomers make up lactose?

  glucose+galactose
• describe glycogen


  energy storage in animals and formed from alpha glucose. Joined together by 1-4 and 1-6 glycosidic bonds. Large but compact. Insoluble, will not effect the water potential.
• decribe starch


  energy store in plants. mixture of amylose- unbranched chain of alpha glucose joined by 1-4 glycosidic bonds, therefore compact. amylopectin- branched made up of 1-4 and 1-6 glycosidic bonds. Insoluble, so will not effect the water potential.
• describe cellulose


  strength and support in plant cell walls. long, unbranched chains of beta glucose. microfibrils made of long cellulose chains running parallel to one another joined by hydrogen bonds.
• Describe the test for reducing sugars


  Add food sample to test tube. Add benedicts reagent and heat. Blue to orange,yellow,red.
• Describe the test for non-reducing sugars


  if you get a negative result for the reducing sugars test and dilute HCl to the food sample and heat. then add sodium hydrogencarbonate. add benedicts reagent and wait for a colour change.
• Describe the structure of a triglyceride


  one molecule of glycerol and three fatty acids joined by ester bonds.
• what's the difference between a saturated and unsaturated fatty acid?

  saturated fatty acids contain single bonds whereas unsaturated contain at least one double bond between carbon atoms. unsaturated fats cannot pack together as tightly and are therefore liquid at toom temperature.
• what are the properties of triglycerides?

  excellent energy storage due to high ratio of H-C bonds. Good storage molecule due tot he low mass. insoluble in water therefore will not effect the water potential.
• describe the structure of a phospholipid

  molecule of glycerol, two fatty acids and a phosphate group bonded by ester bonds. the phosphate heads are hydrophilic and the fatty acid tails are hydrophobic.
• describe the test for lipids

  add the food sample to a test tube. add ethanol and water. a white emulsion will form if a lipid is present.
• describe the primary structure of a protein

  a chain of amino acids
• describe the secondary structure of a protein

  the chain of amino acids twist or fold to form an alpha helix or a beta pleated sheet. weak hydrogen bonds form.
• describe the tertiary structure of a protein

  further folding and twisting. disulfide bridges, ionic and hydrogen bonds form.
• describe the quaternary structure of a protein

  multiple polypeptide chains linked.
• describe the test for proteins


  place the sample in a test tube and add sodium hydroxide. add copper sulfate solution. colour change blue to purple.
• Monomers


  Small units which are the components of larger molecules
• Polymers


  Molecules made from many monomers joined together
• Monomer joining


  1. Condensation reaction

  2. Water molecule eliminated

  
• Polymer breaking down


  1. Hydrolysis

  2. Water added to break chemical bond
• Carbohydrates


  Molecules consisting only of carbon, hydrogen and oxygen, long chains of sugar units called saccharides
• Monosaccharide


  Single sugar unit
• Disaccharide


  Two monosaccharides joined together
• Polysaccharide


  Many monosaccharides joined together
• Glycosidic bond


  Bond formed between monosaccharides in a condensation reaction

  
• Glucose


  • Six carbon atoms in each molecule
  • Main substrate for respiration
  • Has alpha and beta isomers

  
• Common monosaccharides


  • Glucose
  • Galactose
  • Fructose

  
• Disaccharide formation


  1. Condensation reaction

  2. Water molecule produced
• Polysaccharides


  Formed from many glucose units joined together
• Polysaccharides


  • Glycogen
  • Starch
  • Cellulose
• Glycogen


  • Main energy storage molecule in animals
  • Formed from alpha glucose
  • Has many side branches
  • Compact molecule to maximise energy storage
  • Insoluble so doesn't affect water potential

  
• Starch


  • Energy storage in plants
  • Mixture of amylose (unbranched) and amylopectin (branched)
  • Insoluble so doesn't affect water potential
  • Compact to store a lot of energy
  • Easily hydrolysed to release alpha glucose

  
• Cellulose


  • Component of plant cell walls
  • Made of long, unbranched chains of beta glucose
  • Microfibrils formed by parallel cellulose chains joined by hydrogen bonds
  • Provides structural support and prevents cell wall bursting
• Benedict's test for reducing sugars

  1. Add sample to Benedict's reagent

  2. Heat in water bath

  3. Red precipitate indicates reducing sugar

  
• Benedict's test for non-reducing sugars

  1. Add sample to Benedict's reagent, no colour change

  2. Hydrolyse with dilute HCl

  3. Neutralise with NaHCO3

  4. Retest with Benedict's reagent, colour change indicates non-reducing sugar

  
• Iodine/potassium iodide test


  Blue/black colour indicates presence of starch
• Lipids


  Biological molecules made of carbon, hydrogen and oxygen, only soluble in organic solvents
• Triglycerides


  Lipids made of one glycerol molecule and three fatty acids joined by ester bonds