3.1.4.1 Protein

Question 1

Function of protein

Answer 1

Growth and repair
Enzyme
Hormones
In the cell membrane
Structural, protein, collagen
Antibodies in immune system
Transport in haemoglobin
Muscle contraction

Question 2

What make a protein?

Answer 2

Carbon, hydrogen oxygen nitrogen
Some contain sulphur and phosphorus

Question 3

General structure of protein

Answer 3

Amino group (H-N-H)
Variable group (H-C-R)
Carboxylic group (o=c-oh)

Question 4

Polymerisation

Answer 4

Chain of many amino acid
Few chain of polypeptide form protein
Protein can be made up of one polypeptide chain or many

Question 5

Biuret test

Answer 5

Add biuret reagent (sodium hydroxide and copper (ll) sulphate
Purple colour indicate presences of peptide bond there fore protein (negative result with blue solution will show if just prescience of amino acid )

Question 6

Apparatus accurately measure the concentration of protein

Answer 6

Colorimeter

Question 7

Explain how change in primary structure of a globular protein may result in a different 3-D structure

Answer 7

sequence of amino acid will be change in primary structure
The place where hydrogen bond together, it’s different
So it is fold/ coiled in a different way
Tertiary structure change

Question 8

Four level of protein

Answer 8

Primary
Secondary
Tertiary
Quaternary

Question 9

Primary structure

Answer 9

The sequence of amino acid

Question 10

Secondary structure

Answer 10

The primary structure is put into the secondary structure by hydrogen bond between nearby oxygen and hydrogen forming alpha helix or beta platted sheet

Question 11

Tertiary structure

Answer 11

R group interaction pulls the secondary structure into a more complex 3D shape.
Ionic bond (opposite charge ions)
Disulfide bond
Hydrogen bond
Hydrophobic interactions
Hydrophilic interaction

Question 12

Quaternary structure

Answer 12

Two or more peptide chain bond together
Prosthetic group ( non protein ) may also be present
E.g iron in haemoglobin

Question 13

Example of protein

Answer 13

Haemoglobin
Collagen
Enzyme

Question 14

Explain Haemoglobin

Answer 14

• quaternary
• globular protein
• metabolic role
• soluble in water
• spherical shape

Question 15

Explain collagen

Answer 15

In fibrous tissue (tendons join muscle to bone)
Structural role
Insoluble in water
Form fibre
Triple helix

Question 16

Exam Q : full description of structure of protein

Answer 16

Polymer of amino acid
joined by peptide bond
formed by condensation
primary structure is order/ sequence of amino acid
Secondary structure is folding of polypeptide chain due to hydrogen bonding
Tertiary structure is 3D folding due to hydrogen bond, ionic and disulphide bridges
Quaternary structure is 2 or more polypeptide chain