1 Science 10 Unit III: Genetics Genetic Research Genetics research is continually changing and developing in response to new discoveries. Scientists want to learn about sequences of genes that are associated with certain inherited traits as well as how those genes play a role. Human Genome Project Completed in 2003 after 13 years of study, scientists determined, base by base, the DNA sequence of the human genome. Goals of the Human Genome Project included identifying all of the human genes and making them available for study. Identifying the genome sequences of humans and many other organisms allows for a much more comprehensive understanding of biological systems that researchers can apply in human health, agriculture, and the environment. Surprising Discoveries • Only about 2 percent of the nucleotides in the human genome make up our genes and code for all the proteins in the body. • The estimated 25 000 total number of genes is much less than scientists predicted. Previous estimates were between 80 000 and 140 000. • Over 50 percent of our DNA consists of stretches of repeating sequences. • There is very little genetic variation within our species. About 99.9 percent of the DNA sequence is almost exactly the same in all people.