Final answer:
The genetic code's variety comes from the arrangement of four nitrogenous bases into 64 possible codon combinations that encode for 20 amino acids, despite the limited number of bases. The massive number of possible nucleotide sequences accommodates the vast diversity within and among species.
Step-by-step explanation:
Even though the genetic code in DNA consists of only four nitrogenous bases (– adenine (A), cytosine (C), guanine (G), and thymine (T) – the way in which these bases are sequenced can produce an immense variety of genetic information. The bases are organized into triplets, known as codons, each of which specifies a single amino acid, with 64 possible codon combinations.
This is more than sufficient to encode all 20 amino acids that are the building blocks of proteins, due to the redundancy of the genetic code where several codons can code for the same amino acid. Furthermore, the vast number of nucleotides present in an organism's DNA allows for incredibly diverse sequences to exist, facilitating the variety among organisms of the same species.
Each codon of the genetic code maps to one amino acid or a start/stop signal during the process of translation, where ribosomes synthesize proteins by decoding the mRNA transcript of a gene. With nearly 22,000 genes stored within human DNA, the genetic blueprint for building a body is unique to each individual, except for identical twins. This diversity in the genetic sequence is what leads to the complexity and diversity of life that we observe in nature.