Proteins

Question 1

Structure of an amino acid

Answer 1

• four groups attached to a central carbon atom

Primary structure is held together by peptide bonds via condensation reaction

secondary structures include alpha helix and beta sheet

secondary structure is held together by hydrogen bonds. (FON)

Tertiary structure is held together by :
- hydrogen bonds
- ionic bonds
- VDW
- Disulphide bridges

Question 2

What is a nucleotide ?

Answer 2

a nucleotide is a unit that contains 3 components :

• a 5 carbon sugar ( pentose)
• a nitrogenous base
• a phosphate group

Question 3

Construction of a nucleoside

Answer 3

A nucleoside is the dimer that is formed when one of the pentoses is linked to on the nitrogenous bases. The link always occurs via the C1 carbon on the pentose to :

• the N9 on a purine base
• the NQ in a pyrimidine base