Answer:
Base
Explanation:
Deoxyribonucleic acid, DNA, is one of the four major biomolecules in living organisms. It is a polymer made up of monomers called NUCLEOTIDES. The nucleotides that make up a DNA molecule is composed of three substances namely: Sugar (deoxyribose), nitrogenous base, and a phosphate group.
However, among these three components of the nucleotide monomer, NITROGENOUS BASE is the only portion that is not the same in every DNA molecule. There are four nitrogenous bases in nature viz: Adenine, Guanine, Cytosine and Thymine. These four bases can be alternated in a DNA molecule.
Note that, phosphate group and deoxyribose sugar are constant in every DNA.
