1.6. Proteins

Question 1

What is the structure of an amino acid

Answer 1

• NH2 (Amino group)
• COOH (Carboxyl group)
• H (Hydrogen atom)
• R (variety of different chemical groups)

Question 2

How is a peptide bond formed

Answer 2

In a condensation reaction in which the water is made by combining an -OH on a carboxyl group of one amino acid with an -H from another amino acid.

This creates a new peptide bond

Question 3

What are the 4 structures of a protein

Answer 3

Primary

Secondary

Tertiary

Quarternary

Question 4

What do the 4 structures mean

Answer 4

Primary - Amino acid sequence of a proteins polypeptide chains

Secondary - Shape which the polypeptide chain forms as a result of hydrogen bonding. Usually Alpha helix or Beta Pleated sheet

Tertiary - Bending and twisting of the polypeptide. 3 types of bonding - disulfide, ionic and hydrogen, contribute to the maintenance of the tertiary structure

Quaternary - Combination of a number of different polypeptide chains

Question 5

Secondary structure of proteins

Answer 5

The linked amino acids that make up the polypeptide contain both NH and C=O Groups.

The hydrogen and oxygen form hydrogen bonds - twisting it into a 3D shape

Question 6

Bonds within the tertiary structure of proteins

Answer 6

1. Disulfide bridges - Strong and not easily broken
2. Ionic bonds - Formed between any carboxyl and amino groups not involved in peptide bond formation
3. Hydrogen bonds - Numerous but easily broken