Question

Humans are almost identical in the protein-coding sections of the genome, yet each individual has a unique DNA profile. Explain how this is possible.

Answer 1

Basically, every human's individuality lies in its gene but more on the sequences that are surrounding that gene. When these sequences interact with certain key proteins, they are called transcription factors and humans vary in these, that affect our appearance, development etc.

Genes basically makes protein work that vary by only 0.025% in humans. Proteins in our body code for about 1-2% i.e coding regions comprise of 1-2% whereas 98-99% comprises of the non coding region (ehich include introns, repeatative DNA, regulatory DNA etc). This non coding region vary about 1-4% in its sequence among humans. Even a slight change in the sequence of DNA affects the transcription factors i.e binding of sequence to the key proteins gets affected. According to human genome project, our DNA comprises of 3 billion base pairs (i.e A,T,G and C), about 20,000 genes make up the genome and out of these only 1-2% consists of 3 billion base pairs. Some bacteria, humans has the gene encoding the same protein and therefore they show some similarity as the encoded protein performs the same function.

Even though humans are identical in protein coding sections of genome,total amount of genomic DNA varies, proportion of coding and non coding regions varies. Non coding region is responsible for epigenetic activity, gene inteactions etc. The basic uniqueness in DNA among individuals lies in those 3 billion base pairs, since even a slight variation in the genome can be a cause for variation. Even DNA present in a single individual can show variations, and when sequenced its genome will be a unique. Also, each generation shows tiny mutations that tends to carry forward (random mix from mother and father).

These are the reasons why each individual has a unique DNA profile despite similarities in their protein coding regions of genome.