Question

A homopolymer has only one type of building block called monomer repeated 'n' a number of times. A heteropolymer has more than one type of monomer. Proteins are heteropolymers usually made of
A) 20 types of monomer
B) 40 types of monomer
C) 30 types of monomer
D) Only one type of monomer

Answer 1

Hint: Proteins are the biomolecule that is made up of several repeating units of amino acid. Each amino acid is known as a monomer. The monomers are linked together with the help of a peptide bond. Thus, proteins are known as polypeptides.

Complete answer:
A polymer is a macromolecule that comprises repeating units. When the repeating units are similar as in the case of cellulose it is known as a homopolymer and when the repeating units are different it is known as a heteropolymer. Protein is an example of a heteropolymer that contains several monomers of amino acids.

Structure of protein- The protein is a heteropolymer that is made up of 20 different types of amino acid linked together by the peptide bond. The peptide bond is formed as a result of the condensation reaction between two amino acids which yield one water molecule and peptide bond.

There are three types of protein structure-
I) Primary- when the different amino acids are joined in a linear fashion, it forms a primary structure.
II) Secondary- It is a 3D structure of a protein in which hydrogen is formed between the two layers of the polypeptide. It results in alpha-helices and beta-pleated sheets.
III) Tertiary- This structure is formed as a result of the bond between the functional group of the amino acid. It is more complex than the other two.


As the amino acids are 20 in numbers and each is a monomer in forming the polypeptide chain. We can say that the correct answer is A.

Note: The amino acids which are not synthesised in our body and are taken from an external source are known as essential amino acids. The amino acids are important for the growth and development of the body. It is also essential for carrying out physiological functions in our bodies.