Biological Molecules Flashcards
What are the three most important biological molecules
Carbohydrates, proteins and fats
What elements do they all contain?
Hydrogen, oxygen and carbon
What extra does protein also contain?
Nitrogen
Carbohydrate definition
Biological molecule formed of sugar sub units. Carbohydrates differ by having different amounts and types of sub units
Protein definition
Biological molecules formed of amino acid sub-units. Proteins can be structural or functional and they differ by having different amounts and types of amino acids and having them arranged in different orders
Lipids (fats) definition
A basic molecule of fat contains three fatty acids and one glycerol
Test for starch?
Starch test
Add iodine
Colour change from yellowbrown to blueblack if starch is present
Test for sugar
Benedict’s test
Add Benedict’s solution and heat in water bath
Colour change form blue to brick red precipitate
Test for Protein
Biuret test
Add sodium hydroxide, the a few drops of copper sulfate and shake
Colour change blue to lilac
Test for lipids
Ethanol test
Add ethanol then an equal amount of water
Colour change of clear to milky white emulsion
What is a main use of fat?
Storage, as the are high in energy
