20 Facts About the Human Genome 1. The genome is the complete list of coded instructions needed to make a person. 2. The 4 letters in the DNA alphabet - A, C, G and T - are used to carry the instructions for making all organisms. The order (or sequence) of these letters holds the code just like the order of letters that makes words mean something. Each set of three letters corresponds to a single amino acid. 3. There are 20 different building blocks - amino acids - used in a bewildering array of combinations to produce our proteins. The different combinations make proteins as different as keratin in hair and haemoglobin in blood. 4. The information would fill a stack of paperback books 200 feet high. 5. The information would fill two hundred 500-page telephone directories. 6. Between humans, our DNA differs by only 0.2%, or 1 in 500 bases (letters). (This takes into account that human cells have two copies of the genome.) 7. If we recited the genome at one letter per second for 24 hours a day it would take a century to recite the book of life. 8. If two different people started reciting their individual books at a rate of one letter per second, it would take nearly eight and a half minutes (500 seconds) before they reached a difference. 9. A typist typing at 60 words per minute (around 360 letters) for 8 hours a day would take around 50 years to type the book of life. 10. Our DNA is 98% identical to that of chimpanzees. 11. The estimated number of genes in both humans and mice is 60,000-100,000; in the round worm (C. elegans), the number is approximately 19,000; in yeast (S. cerevisiae) there are around 6,000 genes; and the microbe responsible for tuberculosis has around 4,000. 12. The vast majority of DNA in the human genome - 97% - has no known function. 13. The first chromosome to be completely decoded was chromosome 22 at the Sanger Centre (now the Wellcome Trust Sanger Institute) in Cambridgeshire, in December 1999. 14. There is 6 feet of DNA in each of our cells packed into a structure only 0.0004 inches across (it would easily fit on the head of a pin). 15. There are 3 billion (3,000,000,000) letters in the DNA code in every cell in your body. 16. There are 100 trillion (100,000,000,000,000) cells in the body. 17. If all the DNA in the human body was put end to end it would reach to the sun and back over 600 times (100 trillion x 6 feet divided by 93 million miles = 1200). 18. 12,000 letters of DNA are decoded by the Human Genome Project every second. 19. If all three billion letters were spread out 1mm apart they would extend 3,000 km or about 7,000 times the height of the Empire State Building. 20. If all three billion letters were spread out 3mm apart they would extend 9,000km more than twice the length of the Mississippi river at 3,779km.
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