2.1.2klm) To explain the levels of structure in proteins

Question 1

Primary structure

Answer 1

The sequence of amino acids in a peptide chain

Question 2

Secondary structures

Answer 2

a-helices & B-pleated sheets
Form as a result of hydrogen bonding between different amino acids in the chain
H bonds can form -CO of 1 amino acid & the -NH of another/ -OH of another

Question 3

Tertiary structure

Answer 3

Secondary structures fold up to form a very precise 3-D structure

Question 4

Forces responsible for tertiary structure

Answer 4

Hydrogen bonds
Ionic bonds
Disulphide bonds
Van der Waals forces

Question 5

Quaternary structure

Answer 5

More than 1 polypeptide bond in a precise 3-D structure
Polypeptide chain held together in a quaternary structure by tertiary forces
Additional non-amino acid derived groups- prosthetic groups

Question 6

Globular proteins

Answer 6

Form a spherical mass with a specific 3-D shape
Fold up so that hydrophilic groups- outside the molecule & hydrophobic groups-inside the molecule

Question 7

Fibrous proteins

Answer 7

Form long chains of fibres
Fibrous nature- makes them insoluble in water: make them useful for structure & support