2. C Biological molecules

Biology Edexcel IGSCE Carbohydrates, Proteins and Lipids

What elements make up Carbohydrates?

Carbon, oxygen and hydrogen

What elements make up proteins?

• Carbon

• Oxygen

• Hydrogen

• Sulfur

• Nitrogen

• Phosphorus

What elements make up lipids?

Carbon, Oxygen and Hydrogen

What is carbohydrates monomer (smallest version of it)?

Simple sugars/monosaccharides

What is protein’s monomer (smallest version of it)?

Amino acid

What can lipids be broken down into?

• 3 fatty acid molecules

• A glycerol molecule

What is the test for glucose?

• Add Benedict’s solution to the test tube

• Heat the test tube (at 60-70 degrees for 5 mins)

• If glucose is present, the solution will turn brick red (traffic light system)

• If glucose is not present, the solution will remain blue

What is the test for starch?

• Add Iodine to the solution in a dimple tile

• If starch is present the solution will turn blue-black

• If starch is not present, the solution will remain brick red/brown

What is the test for protein?

• Add Biuret to the solution in a test tube

• Leave for one minute

• If protein is present the solution will turn purple

• If protein is not present the solution will remain blue

What is the test for fat?

• Add ethanol to the solution in a test tube

• Add water to the solution

• Leave for 3 minutes

• If fat is present, a milky white emulsion will form

• If fat is not present, the solution will remain colourless