biological molecules

• monomers can be joined together to form polymers
• 3 examples of monomers; monosaccharides , amino acids , nucleotides
• 3 examples of polymers; polysaccharides , protiens , polynucleotides
• monomers join together via condensation reactions
• condensation reaction = removal of water
• carbohydrates contain; hydrogen , carbon and oxygen
• what do carbohydrates do; store energy and provide structure in cell walls
• 3 types of carbohydrate; monosaccharide , disaccharide , polysaccharide
• 3 examples of a monosaccharide; glucose , fructose , galactose
• all monosaccharides are reducing sugars
• to find if a solution contains a reducing sugar use the benedicts regent test
• benedicts regent test;

  1. add 1cm³ of test solution and benedicts regent to a test tube
  2. mix and place into a water bath for 5 minutes
  3. if a red precipitate forms there is reducing sugars
• when two monosaccharides join together via a condensation reaction they form a disaccharide and water
• 3 examples of a disaccharide; maltose , lactose , sucrose
• glucose + fructose = sucrose
• glucose + fructose = sucrose
• glucose + galactose = lactose
• glucose + galactose = lactose
• glucose + glucose = maltose
• glucose + glucose = maltose
• which two disaccharidea are reducing sugars; maltose and lactose
• which disaccharide is not a reducing sugar; sucrose
• benedict regents for a non reducing sugar;

  1. add 1cm³ of dilute hydrochloric acid to 1cm³ of test solution and gently boil in a water bath
  2. add sodium hydroxide and 1cm³ of benedicts solution
  3. heat for 5 minutes
  4. if red precipitate forms a non-reducing sugar is present
• 3 examples of a polysaccharide; starch , cellulose , glycogen
• starch = found in plant cells

  cellulose = found in plant cells

  glycogen = found in liver + muscle cells
• structure of starch;

  • made from alpha glucose
  • 1-4 and 1-6 glycosidic bonds
  • branched, helical, compact structure
• structure of glycogen;

  • made from alpha glucose
  • 1-4 and 1-6 glycosidic bonds
  • highly branched structure
• structure of cellulose;

  • made from beta glucose
  • 1-4 glycosidic bonds
  • unbranched, straight structure
• properties of starch;

  • doesn't affect water potential of a cell
  • compact; easy to store
  • easily transported and used
  • easy for enzymes to act upon
• properties of glycogen;

  • shorter and more branched than starch
  • used for quick-release energy
• properties of cellulose;

  • chains run parallel to eachother
  • chains form cross links with hydrogen bonds
  • prevents cells from bursting
  • keeps plant rigid
• lipids provide twice the amount of calories as proteins and carbohydrates
• lipids help with;

  waterproofing , insulation and protection
• lipids are insoluble in water
• lipids are made from glycerol and fatty acids
• the two types of lipids are;

  1. triglycerides
  2. phospholipids
• triglycerides are made from 1 glycerol and 3 fatty acids
• fats and oils make up triglycerides
• phospholipids are made from one glycerol, two fatty acids and a phosphate group
• phospholipids have a polar, hydrophilic head and a non-polar hydrophobic tail