How do dna, chromosomes, and genes work as the instructions for heredity?

DNA or deoxyribonucleic acid is the molecule in living organisms wherein the genetic code or genes is stored. The structural conformation of DNA in the nucleus of the cells is called chromatin and in cell division, chromatin is grouped into a certain number (46, in humans, for instance) called chromosomes.

DNA provides instructions for hereditary such that a part of DNA is transcribed into messenger RNA or mRNA for the genetic code to be transported outside the nucleus. The mRNA is then translated into polypeptides to form proteins that form specific functions in the human body.