4: Biological Molecules Flashcards
List the chemicals that make up:
Carbohydrates, fats, and proteins
Carbohydrates: Carbon (c) , hydrogen (h), and oxygen (O)
Fats: Carbon , hydrogen oxygen
Protein: Carbon, hydrogen, oxygen, nitrogen, suplur
What are fatty acid molecules made of?
fatty acids and glycerol
What is a starch molecule made of?
glycogen and cellulose from glucose
Describe the use of the iodine solution test for starch:
1: Place a sample (1ml or 1g) into the well of a spotting tile
2: Add 1 ml of iodine solution
3: If starch is not present the colour remains yellow-brown
4: If starch is present the colour changes from yellow-brown to blue-black
What is a protein molecule made of?
amino acids
Describe the use of the iodine solution test for starch:
1: Place a sample (1ml or 1g) into the well of a spotting tile
2: Add 1 ml of iodine solution
3: If starch is not present the colour remains yellow-brown
4: If starch is present the colour changes from yellow-brown to blue-black
Describe the use of the iodine solution test for starch:
1: Place a sample (1ml or 1g) into the well of a spotting tile
2: Add 1 ml of iodine solution
3: If starch is not present the colour remains yellow-brown
4: If starch is present the colour changes from yellow-brown to blue-black
Describe the use of the iodine solution test for starch:
1: Place a sample (1ml or 1g) into the well of a spotting tile
2: Add 1 ml of iodine solution
3: If starch is not present the colour remains yellow-brown
4: If starch is present the colour changes from yellow-brown to blue-black
Describe the use of the iodine solution test for starch:
1: Place a sample (1ml or 1g) into the well of a spotting tile
2: Add 1 ml of iodine solution
3: If starch is not present the colour remains yellow-brown
4: If starch is present the colour changes from yellow-brown to blue-black
Describe the use of the iodine solution test for starch:
1: Place a sample (1ml or 1g) into the well of a spotting tile
2: Add 1 ml of iodine solution
3: If starch is not present the colour remains yellow-brown
4: If starch is present the colour changes from yellow-brown to blue-black
Describe the use of Benedict’s solution test for reducing sugars
1: If the food is solid, you should use a mortar and pestle to grind it into a paste, then dissolve it in water.
2: Using a syringe, place 1 ml of the sample in a boiling tube.
3: Add 1 ml of Benedict’s solution
4: Heat the boiling tube in a hot water bath (100ºC) for 1 min.
5: If a reducing sugar is not present the solution remains blue. If a reducing sugar is present the solution changes colour from blue>green>yellow>red
Describe the use of the Biuret test for proteins
1: if the food is solid, you should use a mortar and pestle to grind it into a paste, dissolve it in water
2: using a syringe, place 1 ml of the sample in a test tube
3: add 1 ml of sodium hydroxide solution. take care, as this is a strong alkali
4: shake the tubes gently, to mix the sample and solution
5: add a few drops of dilute copper sulphate solution and gently shake
6: if protein is not present, the solution should remain blue. if it is, then it should change from blue to lilac
Describe the use of the ethanol emulsion test for fats and oils
1: place a small food sample (1 g or 1 ml) in a test tube (grind/crush first if necessary, but do not add water)
2: add 1 ml of ethanol and shake well to allow any lipids present to dissolve.
3: filter solution (if required)
4: pour the filtrate into a second test-tube containing 10 ml of water
5: if fat is not present the solution remains clear. if it is, colour changes from clear to white as an emulsion forms
Describe the use of the DCPIP test for vitamin c
1: if the food is a solid, you should use a mortar and pestle to grind it into a paste, then dissolve it in DCPIP
2: Using a syringe place 1 ml of a 0.1% DCPIP solution into a test tube
3: Draw 1 ml of the sample into another syringe
4: Add the sample drop by drop to the DCPIP in the test tube
5: If Vitamin C is not present the DCPIP will remain blue, if it is then it will decolourise
