Question

1. What type of reaction links two amino acids into a dipeptide?

2. What functional groups are found in the peptide backbone?

3. Would a peptide in solution be vulnerable to cleavage by addition of a strong base to the solution?

4. Where does the R group or side chain connect to the backbone of an amino acid?

5. Are polypeptides linear or branched polymers?

6. Where are hydrophobic side chains generally found in a globular protein?

7. Where are hydrophilic side chains generally found in a globular protein?

8. What non-covalent interaction stabilizes an alpha helix?

9. What non-covalent interaction stabilizes an beta sheet?

10. What is the most important feature of primary structure?

11. What mediates the formation of tertiary structure in a polypeptide or protein?

12. What distinguishes quaternary structure from tertiary structure?

13. What non-covalent interactions are disrupted when a protein is denatured?

14. What amino acid residues participate to form a disulfide bond?

15. Does a protein that exists as a monomer have quaternary structure? Explain your answer, a simple yes or no will receive no credit?

Answer 1

1. Condensation reaction.

2. The Amide group having structure

3. No,due to addition of a strong base,the pH increases and the -COOH units loose their protons.

4. Alpha carbon atoms of the amide backbone

5. Linear polymers.

6.The Hydrophobic side chain are buried deep inside the interior of the molecule.

7. Hydrophilic side chains are found on the surface of the molecule.

8. Hydrogen bonding.

9. Hydrogen bonding.

10. The principal feature of primary structure in proteins is the peptide bonding.

11. The different types of bonding present in polypeptides such as

• Hydrogen bonding
• Hydrophobic and Hydrophilic interactions
• Disulfide bonds
• Salt Bridge interactions ,

chiefly mediate the tertiatry structure of proteins.

12. Protein having more than one amino acid chain is said to have a quaternary structure whereas primary structure is a three dimensional structure which arises due to side chain interactions.

13. The Hydrogen bonding interactions are disrupted.

14. The Cysteine residues form the disulfide bonds .

15. Quaternary structure is applicable for only those proteins which has two or more subunits(or monomers).So basically a monomeric protein cannot have a quaternary structure.