3.1.4.1

Question 1

Which monomer makes up proteins?

Answer 1

Amino acids

Question 2

What is the general structure of an amino acid?

Answer 2

R
|
H2N ——– C ——- COOH
|
H

Question 3

Label each group in an amino acid.

Answer 3

NH2 = amine group
COOH = carboxyl group
R = variable group

Question 4

How many amino acids are there?

Answer 4

20

Question 5

How are the 20 amino acids different?

Answer 5

Their ‘r’ group / side chain

Question 6

How is a peptide bond formed?

Answer 6

A condensation reaction between two amino acids

Question 7

How is a dipeptide formed?

Answer 7

By the condensation of two amino acids

Question 8

How are polypeptides formed?

Answer 8

By the condensation of many amino acids

Question 9

How are peptide bonds broken?

Answer 9

Hydrolysis by proteases

Question 10

Describe the primary structure of a protein

Answer 10

Sequence of amino acids in the polypeptide chain joined by peptide bonds through condensation reactions
Order determined by genetic code
Position of amino acid determines the bonds formed between the amino acids to produce further levels of structure

Question 11

Describe the secondary structure of a protein

Answer 11

The shape the primary structure folds or coils into
Alpha helix- spiral held by hydrogen bonds
Beta pleated sheet- polypeptide chains form layers with hydrogen bonds between them

Question 12

Describe the tertiary structure of a protein

Answer 12

Further folding or coiling of the secondary structure to form a globular or fibrous molecule
Gives characteristic shape closely related to its function
Held by hydrogen bonds, ionic bonds, disulphide bridges or hydrophobic interactions

Question 13

Describe the quaternary structure of a protein

Answer 13

When more than one polypeptide chain is involved in a protein.

Question 14

Describe the test used for proteins

Answer 14

Add biuret reagent (equal amounts of copper sulphate and sodium hydroxide)
If protein present will turn from blue to purple