biological molecules

• What elements are in carbohydrates?

  carbon, hydrogen, oxygen
• What elements are in proteins?

  carbon, hydrogen, oxygen, nitrogen
• What elements are in lipids?

  carbon, hydrogen, oxygen
• what is an enzyme

  a biological catalyst that speeds up biological reactions

  is a protein

  nearly all chemical reactions in cells require enzymes eg. respiration, photosynthesis
• what happens when an enzyme is denatured

  the active site changes shape so the substrate no longer fits and is no longer complimentary - this is irreversible
• what causes enzymes to be denatured

  extremes of pH

  high temperatures
• What smaller units make up proteins?

  amino acids
• what smaller units make up lipids?

  glycerol + 3 fatty acids ( so not a polymer)
• how can you identify an enzymes optimum pH/ temperature?

  it is the point where the activity is highest, slightly before and after this it has a working rage where it doesnt work as well but not yet denatured
• why do enzymes only work on certain substrates

  each type of enzyme is made of a unique sequence of amino acids and a different shape so it will have a unique active site that only complementary substrates will fit into
• how do you test for proteins in a substance

  add several drops of biuret solution to the sample

  
  

  positive test: change from blue to lilac/purple
• how do you test for lipids in a substance

  mix an equal amount of the sample with ethanol - shake a lot with bung on top

  then add an equal volume of distilled water - shake again

  
  

  positive test: will go white and cloudy, usually in layer on top of mixture.
• how do you test for starch in a substance

  add a few drops of iodine

  
  

  positive test: change from brown/yellow to blue/black
• how do you test for glucose

  add equal amount of Benedict's solution and heat in water bath

  
  

  positive test: brick red shows high amount
• Simple carbohydrates


  Also known as sugars, provided by sweet foods like chocolate, milk, and fruit. Includes monosaccharides and disaccharides
• Complex carbohydrates


  Also known as starch, found in foods like bread, rice, pasta, and potatoes. made up of simple sugars. polysaccharide
• monomer


  a small molecule that bonds to other identical ones to form a polymer
• polymer 


  a long molecule made from monomers
• monosaccharides

  1 subunit

  eg. glucose, fructose, galactose

  found in sugars like fruit and honey
• disaccharides

  2 subunits

  eg. maltose (glucose + glucose), sucrose (glucose + fructose), lactose (glucose + galactose)

  found in dairy
• polysaccharides

  3+ subunits

  eg. starch, glycogen, cellulose (forms plant cell walls)

  found in complex carbohydrates
• what breaks complex carbohydrates into simple carbohydrates


  carbohydrase enzymes in the mouth, small intestine
• where are proteins broken down into amino acids


  stomach and small intestine by enzyme protease
• what breaks down fats

  enzymes in small intestine (lipase)