Question

Which is not a macromolecule?
(a) DNA
(b) Insulin
(c) Palmitate
(d) Starch

Answer 1

Hint: Another name for a macromolecule is a polymer, a common term which we find in chemistry. The word polymer has been derived from the Greek prefix poly- that means “many units."

Complete step by step solution:
A macromolecule is usually a very large molecule, composed through the process of polymerization of smaller subunits called monomers. There are three major types of biological macromolecules present in mammalian systems, namely carbohydrates, proteins and nucleic acids. The monomeric unit for carbohydrates is monosaccharide, amino acids for proteins and nucleotides for nucleic acids. Let us see our options one by one.

(a)- DNA stands for Deoxyribonucleic acid. DNA is considered as a macromolecule because it is a very large molecule. It is a polymer of nucleotides. Nucleotides comprises three parts: pentose sugar, phosphate, and nitrogenous base. The pentose sugar of DNA is deoxyribose. It contains the genetic instructions which are beneficial for the development and function of living things. All existing cellular life and some viruses contain DNA. The main role of DNA in the cell is to store information for long-term.

(b)- Insulin is a protein hormone which is present in the pancreas. It is responsible for regulation of blood-sugar levels. It has a molecular unit derived from 51 amino acids.

(c)- Palmitate (more formally known as retinyl palmitate) contains palmitic acid. Palmitic acid is a 16-carbon saturated fatty acid, which is the major fatty acid found in palm oil. Palmitate is a long chain of fatty acids and thus it is not a macromolecule.

(d)- Starch, also known as amylum, is a polymeric carbohydrate. It consists of numerous glucose units joined by glycosidic bonds. This polysaccharide is produced by most green plants as a form of energy storage.

So, the correct option is (c).

Note: “Large biological molecule” that is present in our food, provides us the building blocks that we need to maintain our body– because our body is also made of large biological molecules.
Carbohydrates store fuel for future energy needs.
Nucleic acids store and transfer hereditary information from one generation to another.
Proteins provide structural support to the cells.