2.1. Nucleus

In the previous chapter, we briefly discussed cell division and how a cell is an independent self-replicating unit. Upon cell division, each daughter cell is capable of independent function, and all the information carried by the mother cell is transmitted to the daughter cells via replication of the genetic material enclosed in the nucleus. As you probably already know, all the genetic information is encoded in four letter codes A, T, C, and G in the double helix of the Deoxyribonucleic acid (DNA). The linear chain of DNA is coiled into structures known as chromosomes and is compactly folded inside the membrane-bound nucleus. The three letter codon combinations encode 20 essential amino acids that are bonded together to form protein chains. For the information to pass from the DNA to protein, the DNA is first copied into messenger RNA (mRNA) molecules inside the nucleus and then transported out of the nucleus. The mRNA molecules are then translated into proteins at the sites of protein synthesis - the ribosomes.