Proteins

Question 1

Protein Structure

Answer 1

Many Polypeptides
Amino Acids
- NH2 = Amine Group
- COOH = Carboxyl Group
- R = chain
- H = Hydrogen
- C = Carbon

Question 2

Condensation of Amino Acids

Answer 2

A Peptide Bond
Dipeptides
- 2x Amino Acids
Polypeptides
- Several Amino Acids

Question 3

Hydrogen Bonds

Answer 3

Strongly Polar R Groups
Most Common Bonds
Weakest Bonds

Question 4

Ionic Bonds

Answer 4

Form between Positively Charged Amine Group and Negatively Charged Carboxylic Acid
Bonds Broken by pH change
Stronger but less Common

Question 5

Disulfide Bonds/Bridges

Answer 5

Form between two Cysteine R Groups
Strongest but less Common
Broken by Reduction Reaction
Common in secreted Proteins e.g. Insulin

Question 6

Test for Proteins

Answer 6

1. Crush sample + Dissolve in water
2. Add Biuret Reagent + Mix
3. Positive Result = Blue –> Lilac

Question 7

Primary Structure

Answer 7

The Sequence of Amino Acids
Bonded by Covalent Peptide Bonds
In a Polypeptide Chain

Question 8

Secondary Structure

Answer 8

Localised Hydrogen and Ionic Bonding
E.g. Alpha Helicase + Beta Pleated Sheets

Question 9

Tertiary Structure

Answer 9

More widespread bonding between Amino Acids
- Hydrogen
- Ionic
- Disulphide Bridges

Question 10

Quaternary Structure

Answer 10

Different Polyeptide Chains make the Protein.