2.10 proteins: amino acids

What are proteins made up of?

Proteins are made up of amino acids.

What names are given to the monomers, dimers, and polymers of proteins?

1. Monomers - amino acids

2. Dimers - dipeptides

3. Polymers - polypeptides

What are the roles of proteins?

1. Enzymes

2. Antibodies

3. Transport

4. Structural components

5. Hormones

6. Muscle contraction

What is the general structure of an amino acid?

Amino acids are made up of:

• A central carbon atom

• An amino group

• A carboxyl group

• A hydrogen atom

• An R group

What determines the properties of an amino acid?

The R group or variable side group.

What type of bond joins amino acids together?

Amino acids are joined via peptide bonds.

What is a dipeptide?

A dipeptide is two amino acids joined by a peptide bond.

How are dipeptides synthesised?

Dipeptides are synthesised via condensation reactions.

The hydroxyl group (OH) in the carboxyl group of one amino acid reacts with the hydrogen (H) in the amino group of another amino acid.

This releases a water molecule and forms a peptide bondbetween two amino acids.

How are dipeptides broken down?

Dipeptides are broken down via hydrolysis reactions.

A water molecule is added to a dipeptide which breaks the peptide bond to release the 2 amino acids. 

Which test can identify proteins?

The Biuret test.

What does the Biuret test detect?

The Biuret test detects the presence of peptide bonds(proteins).

How is the Biuret test carried out?

1. Place the food sample in a test tube. 

2. Add an equal volume of Biuret solution. 

3. If proteins are present, the solution will turn from blue to purple. 

What does a blue colour indicate in the Biuret test?

A blue colour indicates that no proteins are present.