Final answer:
About 1.5% of human DNA is used to create proteins, with humans having approximately 20,000 to 25,000 genes. The rest of the DNA is largely regulatory, aiding in gene activity control and non-coding RNA production. The Human Genome Project has revealed the complexity of these regulatory mechanisms within our genome.
Step-by-step explanation:
Only about 1.5% of human DNA is used to make proteins, which is a remarkably small portion considering that humans have approximately 20,000 to 25,000 genes in their genome. While this may seem a modest number of genes, particularly when compared to some simpler species which have nearly as many, humans achieve a vast array of protein diversity. This is largely due to the processes such as splicing, allowing multiple proteins to be made from a single gene's instructions.
Out of the 3 billion base pairs that make up the human genome, roughly 25 percent constitute genes and regulatory elements, but only 1.5 to 2 percent of these actually code for proteins. The remaining DNA, whose functions are less clear, plays critical roles in regulating gene activity and can be involved in the production of non-coding RNA that helps control gene expression.
Discoveries from the Human Genome Project also identified millions of sites within these non-coding regions where proteins bind to DNA and exert regulatory functions. These intricate and precise controls underscore the complexity of the human genome and hint at the vast regulatory landscape that orchestrates gene expression within human cells.