Answer to SQ Ch. 32 Amino Acids and Peptides Question Bank

1. What are amino acids?
Amino acids are organic compound containing both an amino group and carboxylic group. The amino group is NH-2 and the carboxyl group is COOH.

2. What is the link between amino acids and proteins?
Structurally, proteins are long polymers of amino acids linked by peptide bonds.

3. Give two examples of amino acids with Nonpolar R Group.

Glycine and Alanine (Ref TMH page 32.1)

4. Give two examples of Amino acids with Polar R Group.

Serine and Thronine (Refer TMH Page 32.2)

5. Give two examples of amino acids with charged R group.

Aspartic acid and Lysine (Ref TMH page 32.2)

6. Give two examples of amino acids that cannot be made by human body.

Phenylalanine, Tropophan (Ref TMH 32.1 or Jauhar-XII-Page 954)

7. What is chiral nature of amino acids?
Except glycine all other amino acids contain asymmetric carbon next to the carboxylic acid. So they are all chiral.

8. What is zwitterion?

In highly acidic conditions (pH = around 1), both the carboxylic group and the amino group are protonated. On increasing the pH of the solution, the carboxyl group ionizes to produce a dipolar ion. The doubly charged ion is known as zwitterion(from German meaning double ion). The pH of the ion solution at which the species becomes zwitterion is known as isoelectric point.

9. What is peptide linkage?

The condensation of two amino acids with the elimination of H-2O produces Co-NH linkage, which in protein chemistry, is known as a peptide linkage. (For explanation of condensation and elimination see polymers chapter)

10. What is a dipeptide?

It is a linkage between two amino acids

11. What is the relation between peptide and protein?

Structurally, proteins are long polymers of amino acids linked by peptide bonds.


12. What is the simplest amino acid?

Glycine