Question

What will be the molecular formula of a polypeptide consisting of 10 glycine residues?

• A. $C_6{H}_{12}O{N}_5$
• B. $C_{20}{H}_{32}{O}_{11}{N}_{10}$
• C. $C_{30}{H}_{16}{O}_6{N}_{10}$
• D. $C_{20}{H}_{30}{O}_{12}{N}_{10}$

Answer 1

Answer: (B)

The structure of amino acid glycine is as follows:
C2​H5​O2​N1​ When 10 glycine molecules come together to form a polypeptide chain, 9 peptide bonds will be formed by the loss of 9 water molecules. Thus the molecular formula of the polypeptide will be $\left[\left(C_2{H}_5{O}_2{N}_1\right)\times 10\right]-9H_{2}O=C_{20}{H}_{32}{O}_{11}{N}_{10}$