Science Fair Project Encyclopedia
Human genome
Human genome is the genome of Homo sapiens. It is made up of 23 chromosome pairs with a total of 3×109 base pairs. There are approximately 20,000-25,000 genes in human DNA. The human genome has been mapped by the human genome project. This mapping was finished to 99% on April 14, 2003.
| Contents |
Features
Human genetic material is made up of two distinct components: the nuclear genome and the mitochondrial genome.
The Nuclear Genome
The nuclear genome has 24 kinds of chromosomes: numbers 1 through 22 plus the X chromosome and its smaller partner, the Y chromosome. Both men and women inherit 22 chromosomes from each parent, plus an X chromosome which is always inherited from the mother. Women inherit another copy of the X chromosome, and men a copy of the Y chromosome, from the father.
The Mitochondrial Genome
Both men and women inherit their mitochondrial DNA (mtDNA) from their mother.
Internal Features
About 97% of the human genome has been designated as "junk" DNA. For example, the Alu sequences are repeated some million or so times, and this one family alone accounts for about 5% of human DNA. Single nucleotide polymorphisms make up 90% of all human genetic variations, and occur every 100 to 300 bases along the human genome.
The Genetic Landscapes
The modern human genome shares more than 97% of its DNA with the rest of the genomes in the Hominid family.
See also
External Links
The contents of this article is licensed from www.wikipedia.org under the GNU Free Documentation License. Click here to see the transparent copy and copyright details