Protiens

Question 1

What are proteins made up of ?

Answer 1

• the monomers of proteins are amino acids
• proteins are made up of more than one polypeptide

Question 2

What is the structure of an amino acid?

Answer 2

R
H2N - C - COOH
H
- NH2, amino group
- COOH, carboxyl group
- R, variable group

Question 3

How many amino acids to living things have?

Answer 3

20 amino acids.

Question 4

How is a dipeptide formed?

Answer 4

• amino acids linked together by a condensation reaction producing H2O
• a peptide bond forms between the C in the carboxyl group and the N in the amino group
• a hydrolysis reaction happens when dipeptides/ polypeptides are broken down

Question 5

Primary structure of a protein:

Answer 5

The order sequence of amino acids in a peptide chain.

Question 6

Secondary structure of a protein:

Answer 6

The secondary structure forms as a result of hydrogen bonds forming between amino acids in the chain. This causes folding into alpha helixes and beta pleated sheets.

Question 7

Tertiary structure of a protein:

Answer 7

More folding here as the protein forms its final 3D shape. More hydrogen bonds and ionic bonds form. If amino acids with sulphur are present disulphide bridges will form.

Question 8

Quaternary structure of a protein:

Answer 8

More than one polypeptide chains present. Often associated with a prosthetic group ( non - protein ).

Question 9

Strength of bonds in the tertiary structure:

Answer 9

^ disulphide bridges
I ionic bonds
I hydrogen bonds

Question 10

Biuret test for proteins:

Answer 10

1. Add biuret reagent to the sample
2. Blue -> lilac is a positive result