module 1: biology

• monomers:

  smaller units that can create larger molecules
• examples of monomers:

  monosaccharides : glucose

  nucleotides 

  amino acids
• polymers:

  molecules made from many monomers joining together
• examples of polymers

  polysaccharides : starch,glycogen, cellulose

  DNA & RNA

  proteins
• condensation reaction

  joins 2 molecules together to form a bond by removing water
• hydrolysis reaction

  breaks a bond between 2 molecules whilst using water
• monosaccharides

  monomers from larger carbohydrates
• examples of monosaccharides

  glucose

  galactose

  fructose
• disaccharides

  joins 2 monosaccharides via a condensation reaction forming a glycosidic bond
• how is maltose formed

  glucose + glucose
• how is sucrose formed

  glucose + fructose
• how is lactose formed

  glucose + galactose
• polysaccharides

  condensation reaction of many glucose units
• how is amylose starch formed and its adaptation to function

  Structure:

  made from a-glucose

  unbranched chains

  1,4 glycosidic bonds

  wounded to tight coils

  Adapted to Functions:

  helical chains = compact (used for storage)

  insoluble in water = no osmosis effect

  • large molecule = wont diffuse out of the cells
• how is amylopectin starch formed and its adaptation to function

  Structure:

  made from a-glucose

  branched chains

  1,4 +1,6 glycosidic bonds

  Adapted to Functions:

  branched = hydrolysed rapidly to release glucose for respiration (larger SA)

  insoluble in water = no osmosis effect

  • large molecule = wont diffuse out of the cells
• how is glycogen formed and its adaptation to function

  Structure: 

  made from a-glucose

  1,4 + 1,6 glycosidic bonds

  highly branched 

  Adapted to Functions:

  chains are coiled = compact (used for storage)

  highly branched = hydrolysed rapidly to release glucose for respiration (larger SA)

  • insoluble in water = no osmosis effect
• how is cellulose formed and its adaptation to function

  Structure:

  made from b-glucose

  1,4 glycosidic bond

  straight unbranched chains

  (runs parallel + forms H bonds)

  H bonds formed link chains to form microfibrils

  Adapted to Functions:

  microfibrils provides strength

  resists pressure

  • eg: cell walls contains support & rigidity)
• test for reducing sugars

  benedict's reagent:

  • add benedict's reagent (blue) to sample
  • heat in water bath
• test for non-reducing sugars

  if reducing sugar test is negative:

  • add dilute HCL and heat in water bath
  • neutralise by adding sodium hydrogencarbonate
  • heat sample with benedict's reagent

  positive result: colour change

  • blue → green → yellow → orange → red
• test for starch

  iodine test:

  • add iodine dissolved in potassium iodide solution to sample

  positive result: colour change

  • brown/orange → dark blue/black
• 2 types of lipids:

  triglycerides & phospholipids
• triglycerides

  condensation reaction of 1 glycerol and 3 fatty acids removing 3 molecules of water forming ester bonds
• properties of triglycerides

  energy storage: large ratio of C-H bonds

  metabolic water source: high ratio of H : O

  insoluble: fatty acids = hydrophobic so can’t affect water potential & osmosis

  relatively low in mass: can store a lot of lipids
• phospholipids

  1 phosphate group and a glycerol and 2 fatty acids
• properties of phospholipids

  forms a bilayer

  phosphate group: hydrophilic

  • attracts water

  fatty acids: hydrophobic

  • repels water
• how is an ester bond formed

  through the condensation reaction between a glycerol and fatty acid
• saturated fatty acids

  single bonds between carbon in the hydrocarbon chain
• unsaturated fatty acids

  at least 1 double bond between carbons in the hydrocarbon chain
• test for lipids

  • dissolve sample in ethanol & shake
  • add distilled water

  positive result: white emulsion
• proteins:

  polymers made up of monomers - amino acids
• how is the bond between dipeptides/polypeptides formed

  through a condensation reaction - forming peptide bonds at the OH in carboxyl and H in amino group
• primary structure of proteins

  order of sequence of amino acids
• secondary structure of proteins

  primary structure coiled to make alpha helix / beta pleated sheets

  • held by hydrogen bonds
• tertiary structure of proteins

  folding of secondary structure:

  • has a unique 3D shape
  • consists of: ionic bonds & hydrogen bonds & disulfide bridges
  • between R groups
• quaternary structure of proteins

  more than 1 polypeptide chain joined together

  eg: haemoglobin - has 4 polypeptide chains