Question

What enables Dna to have so many variations with only 4 chemicals?

Answer 1

Even though DNA only has 4 nitrogenous bases there can be variety of combinations for DNA.  One difference in combination would mean a different DNA strand. 

Answer 2

Different combinations between these four set of chemicals

Step-by-step explanation:

There can be billions of combinations between the four chemicals of DNA. The four set of chemicals i.e nucleotide (generally referred to as bases) namely -

A- Adenine

T- Thymine

C - Cytosine

G - Guanine

These nucleotide form codon i.e set of three nucleotide and form chain structure which can be long up to any extent.

Codon example - ATC TGA

Thus, variation in combination of four nucleotide and ability to form long chain of codon allows DNA to have several forms and variations