biological molecules

• monomers


  smaller units from which polymers are made
• polymers


  molecules made from a large number of monomers joined together
• 3 examples of a monomer

  monosaccharides, amino acids, nucleotides
• condensation 


  joins 2 molecules forming a chemical bond and eliminating a water molecule
• hydrolysis 


  breaks a chemical bond between 2 molecules using water
• monosaccharide


  monomers that form larger carbohydrates
• 3 examples of a monosaccharide

  glucose, galactose, fructose
• glycosidic bond


  condensation between 2 monosaccharides
• disaccharide


  condensation of 2 monosaccharides
• 3 examples of disaccharides

  maltose, sucrose, lactose
• maltose


  2 glucose
• sucrose


  glucose and fructose
• lactose


  glucose and galactose
• glucoses two isomers


  a-glucose and b-glucose
• polysaccharides


  condensation of many monosaccharides
• formation of glycogen and starch

  condensation of a-glucose
• formation of cellulose


  condensation of b-glucose
• structure and function of glycogen

  • a-glucose joined by 1,4 and 1,6 glycosidic bonds
  • lots of side branches to release energy quickly
  • large but compact for energy store
  • insoluble so wont affect water potential
• structure and function of starch

  • stores energy in plants
  • mixture of amylose and amylopectin
• amylose

  • unbranched chain of glucose joined by 1,4 glycosidic bonds
  • coiled and compact storing lots of energy
• amylopectin

  • branched glucose joined by 1,4 and 1,6 glycosidic bonds
  • side branches for enzymes to act on
  • broken down to release energy
• starch properties

  • insoluble so doesnt affect water potential
  • compact so lots of energy can be stored
  • when hydrolysed, the released a-glucose is transported easily
• structure and function of cellulose

  • makes up plant cell walls
  • long unbranched chains of b-glucose joined by glycosidic bonds
  • stops cell wall bursting under osmotic pressure
  • cells stay turgid and rigid to increase sa for photosynthesis
• reducing sugars test

  • add food sample to benedicts
  • heat
  • brick red
• non-reducing sugars test

  • add food to benedicts but no colour change
  • add hcl and heat
  • add sodium hydrogencarbonate to neutralise
  • retest with benedicts
• starch test

  • add food to iodine
  • blue/black
• 2 types of lipids

  triglycerides and phospholipids
• triglycerides


  condensation of 1 glycerol and 3 fatty acids
• ester bond


  condensation between glycerol and fatty acid
• saturated fatty acid


  no double carbon bonds
• unsaturated fatty acid


  carbon double bonds
• phospholipids


  condensation of 1 glycerol, 2 fatty acids and a phosphate group
• structure and function of triglycerides

  • high ratio of carbon-hydrogen bonds to carbon atoms so good energy store
  • low mass to energy ratio so lots of energy within a small volume
  • non-polar so insoluble in water
• structure and function of phospholipids

  • polar so forms bilayer in aqueous environments
  • hydrophillic heads to hold at the surface of cell membrane
  • can form glycolipids with carbohydrates for cell recognition
• lipid test

  • add food to ethanol and shake
  • add water and shake
  • cloudy-white emulsion
• amino acid


  monomers from which proteins are made
• peptide bond


  condensation between 2 amino acids
• dipeptide


  condensation of 2 amino acids
• polypeptide


  condensation of many amino acids
• functional protein 


  one or more polypeptides