Cells are the basic and structural unit of life.
All cells have their own DNA(deoxyribonucleic acid)which is present in their nucleus, where all genetic information is, and every being in the world has its own.
Watson and Crick proposed the dual helix model for DNA that is the model accepted nowadays.
DNA molecule is formed by a dual polynucleotide chain because it has various nucleotides (adenine, thymine, cytosine and guanine).
This chain also is helically wound around an imaginary axis and it grows in the direction 5’ to 3’ so it is a anti-parallel chain.
The unit base of the DNA chain is the nucleotide that is formed by a phosphate group, a pentose (deoxyribose) and a nitrogenous base that gives the name to the nucleotide.
To conclude,the nitrogenous bases are complementary; adenine links to thymine through two hydrogen bonds and cytosine links to guanine through three hydrogen bonds, being a stronger bond.
The DNA molecule controls every cellular function essential for the existence of life on the planet, giving us several information about all cellular processes.