Structure and Functions of Proteins and Enzymes

Question 1

Primary structure of protein refers to
A. Linear structure and order of the amino acids present
B. Regular conformational forms of protein
C. Complete 3-D structure of polypeptide units of given protein
D. Subunit structure of the protein

Answer 1

Answer- A. Linear structure and order of the amino acids present

Question 2

Alpha helix and beta pleated sheet are examples of 
A. Primary structure 
B. Secondary structure 
C. Tertiary structure 
D. Quaternary structure

Answer 2

Answer- B. Secondary structure

Examples of secondary structure are
A. Alpha helix
B. Beta pleated sheets
C. Beta turns

Note that secondary structure is stabilised by hydrogen bonds and disulphide bonds.
cooperative hydrogen bonding in repeating secondary structures have an important role in guiding protein folding process. However location of bends( including beta turns) in polypeptide chain and the direction and angle of these turns are determined by the number and location of specific bend producing amino acid residues such as Pro, Thr, Ser, and Gly.

Question 3

The 3 dimensional shape of protein is maintained mainly by 
A. Strong covalent interactions
B. Interactions with other proteins
C. Multiple weak interactions
D. Interactions with prosthetic groups

Answer 3

Answer- C. Multiple weak interactions

Question 4

All of the following assays are used for the estimation of total serum protein, except
A. Biuret
B. Bradford 
C. Lowry's
D. Bromocresol green

Answer 4

Answer- D. Bromocresol green

Bromoscresol green and bromocresol purple dye binding assay is a method for estimation of total serum albumin (not total protein)