Before the completion of the Human Genome Project, most biologists expected to There are 23 chromosomal pairs in the human genome. There are an estimated 20,000-25,000 genes in the human genome. It is approximately 25000 per cell.
The number of genes varies from chromosome to chromosome and the number of chromosomes varies from species to species (from as few as 1 single chromosome per cell to as many 30,000 chromosome pairs per cell). Human cells have 23 chromosome pairs per cell.
Genes only make up about 3% of the human genome. These are the parts that code for a functional product (such as a protein). Parts of DNA that do not code for anything are not genes. The exact number of genes is still debated, but the current estimate for the number of human genes is 20,000-25,000.