Chromosomes and Genes
Date: March 2009
Are the genes present everywhere on chromosome, or on specific
They CAN be anywhere-almost. There aren't any genes on the tips of the
chromosomes in areas called telomeres, or in the area that holds the sister
chromatids together called the centromeres. Other than that, genes can be
found anywhere. But only 1.5% or so is protein coding genes, the rest of the
DNA is non-coding or codes for RNA genes, or is regulatory. Each chromosome
has a different distribution of those genes.
The evidence is that each human chromosome is comprised of one long DNA molecule
made up of approximately 100 million base pairs.
Regions that code for a protein (a gene) can be located anywhere along the
chromosome, but it appears that 90% of the DNA does not code for anything, so-called
"junk" DNA (e.g. introns).
Ron Baker, Ph.D.
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Update: June 2012