Human development- chapter 2- from conception to birth. The beginning of life: everyone starts life as a single cell, called a zygote. Each zygote is distinct from any other human cell ever created: zygote: a single cell that is formed from the fusing of two gametes, a sperm and an ovum. A gene consists of a string of chemicals that provide instructions for the cell to manufacture certain proteins: additional dna and rna surround each gene. In a process called methylation, the material enhances, transcribes, connects, empowers, silence and alter genes. This nongenetic material used to be called junk. Those amino acids combine to produce proteins, and those proteins combine to produce a person. International project: hapmap aims to spot variations in the human genome. 11 million differences among the 3 billion possible chemical pairs in humans. Can be problematic since much remains to be understood about the connection between alleles in the genotype and actual characteristics of the phenotype.