Protein

Question 1

What are proteins made up of?

Answer 1

Amino acids

Question 2

What does an amino acid consists of?

Answer 2

Central carbon
Amino group
Carboxylic group
R side chain

Question 3

What are the types of amino acids?

Answer 3

Non-polar, hydrophobic
Polar, hydrophilic
Acidic
Basic

Question 4

How are amino acids joined together?

Answer 4

Peptide bonds joins amino acids together
Peptide bonds are formed between the -NH2 group of one amino acid and -COOH group of another amino acid, through dehydration

Question 5

What are the forces that hold the protein together?

Answer 5

Various side chains of one amino acid interact with side chains of other amino acids
Many types of bonds are formed

Question 6

What are the levels of protein folding?

Answer 6

Primary structure:

• sequence of amino acids
• no bonds except peptide bonds

Secondary structure:

• amino acids linked together by hydrogen bonds
• alpha-helixes and beta-sheets are formed

Tertiary structure:

• interactions between various alpha-helixes and beta-sheets
• 3D structure

Quaternary structure:
- interactions between 2/more polypeptide chains

Question 7

What are the factors affecting protein folding?

Answer 7

High temperature reduces the strength of hydrogen bonds
Extreme pH alters electrostatic interactions between charged amino acids
Denaturation occurs when proteins/nucleic acids lose the quaternary, tertiary and secondary structure which is present in their native state
Denatured proteins are unfolded and inactive

Question 8

Why do polypeptides fold in aqueous environment?

Answer 8

Hydrophobic residues will cluster in the interior of the protein, causing them to interact
Hydrogen bonds are formed, stabilizing the structure