The human genome has 23 pairs of chromosomes, one inherited from each of our parents. The genome is the blueprint of our genetic makeup. The ovum and the sperm carry these blueprints from our parents. After fertilisation, the combined single cell, with the 23 chromosomes, starts to divide, copying the genetic material over and over to nearly a trillion cells – which make up the human body.
As the cells divide, the DNA is copied with extremely high accuracy thanks to proteins that proofread and correct errors in the DNA. But despite this mechanism, various studies have estimated that there is still an error rate of 0.64-0.78 mutations per billion base pairs per division. But this rate is also minuscule given the large size of the human genome.
