Biological Molecules

• Disaccharides are formed when two monosaccharides are joined together through a glycosidic bond.
• Saturated fatty acids are when there are no double bonds between the Carbon atoms
• Unsaturated fatty acids are when there are 1 or more double bonds between Carbon atoms
• Why are some lipid molecules liquid at RT and harder to break down?

  They are unsaturated-the double bond causes the molecule to bend, and so they cannot pack so closely together.
• Plants contain unsaturated triglycerides (healthy), whereas humans have saturated triglycerides (unhealthy)
• Proteins are made up of amino acids which are linked by peptide bonds
• Lipase is an enzyme that breaks down lipids into smaller components such as fatty acids and glycerol
• Amino Acids consist of an Amino group (-NH2) , a carboxyl group (-COOH) and a variable R-group
• Primary structure is the sequence of amino acids in a protein
• What is esterification?

  When the hydroxyl group of the glycerol and fatty acids interact, leading to the formation of 3 water molecules and bonds between the fatty acids and glycerol molecule --> ester bonds
• What happens when triglycerides are broken down?

  Three water molecules need to be supplied to reverse the reaction --> hydrolysis
• What are phospholipids?

  • They are modified triglycerides
  • Contain the elements hydrogen, carbon, oxygen and phosphorus
• Inorganic phosphate ions have extra electrons and so are negatively charged, making them soluble in water.
• Phospholipids have:

  • a hydrophobic fatty acid tail (non-polar)
  • a hydrophilic phosphate head (charged)
• Phospholipids have:

  • a hydrophobic fatty acid tail (non-polar)
  • a hydrophilic phosphate head (charged)
• Structure of cholesterol:

  • made from 4 carbon rings
  • small, narrow and hydrophobic
  • regulates fluidity + strength of membranes
• Role of lipids:

  • energy store
  • thermal insulation
  • buoyancy
  • protection of organs ie kidney
• How to test for lipids:

  Emulsion test- mix sample with ethanol, then mix with water and shake

  If solution turns cloudy, there are lipids present
• maltose is made from 2 glucose molecules in an alpha 1-4n glycosidic bondd
• sucrose is made from a glucose and fructose molecule in an alpha 1-4 glycosidic bond
• lactose is made from glucose and galactose in a beta 1-4 glycosidic bond
• carbohydrates can be classified as monosaccharides or polysaccharides
• cellulose

  • makes up plant cell walls
  • strong
  • made of beta glucose molecules in a beta 1-4 glycosidic bond
  • formed from inverted beta glucose--> prevents coils/branches from forming
• starch

  • major carb store in plants
  • intracellular starch grains called plastids
  • green chloroplasts and colourless amyloplasts
  • amylose and amylopectin
• glycogen

  • how animals store glucose
  • similar structure to amylopectin
  • many alpha 1-6 glycosidic bonds
  • less dense + more soluble than starch
  • and broken down more rapidly
• amylose

  • unbranched chain
  • 1-4 alpha glycosidic bonds--> coiled + a compact molecule storing a lot of energy
• amylopectin

  • 1-4 and 1-6 alpha glycosidic bonds
  • many side branches