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Facts about Genomes. See 20 Facts about the Human Genome

  • There are 100 trillion (1012) cells in your body. Each cell contains DNA double helix totalling three billion (3 x 109) base pairs.
  • If unwound and linked together, the strands of DNA in one cell would stretch almost six feet but would be only 50 trillionths of an inch wide.
  • It would take about 9.5 years to read out loud (without stopping) the 3 billion bases in a person's genome sequence, if you read at a rate of 10 bases per second.
  • If all the DNA in your body was put end to end, it would reach to the sun and back over 600 times (100 trillion times six feet divided by 92 million miles).
  • Human DNA is 98 percent identical to chimpanzee DNA. Human DNA is 30% identical to E. coli DNA.
  • The average amount of genetic difference between any two humans is 0.2 %, or one in 500 bases. Chimpanzees differ by 0.8 %.

Useful Sites

  • NCBI (National Center for Biotechnology Information)
  • OMIM (Online Mendelian Inheritance in Man)
  • BLAST DNA-DNA comparison
  • Webcutter Restriction enzyme mapping
  • Human Genome


1. Visit Online Mendelian Inheritance in Man (OMIM). Look up "myostatin."

What do you find interesting?

What do we learn about the gene function? Structure? Genetics?

2. At the top left of the myostatin page, click the link  "Cytogenic location 2q32.2."

Where is the gene encoding myostatin; on which chromosome?

What other interesting genes do you find there?

Explore the gene maps linked here.
If you get lost, click here.

3. Back to the Myostatin entry page: Check the menu at right. Click DNA, then NCBI  RefSeq. This brings up the "reference sequence" for human myostatin.

Can you find the DNA sequence? The protein sequence?

4. Go back to OMIM. Type a disease name, any disease of interest to you.

Can you find a gene associated with the disease? Try steps 1, 2, 3 above.

5. Copy this DNA gene sequence fragment:

ctagtgtgcg gggaacgagg cttcttctac acacccaaga cccgccggga ggcagaggac


Paste into BLAST under "Enter Query Sequence."
Search "Human Genomic + transcript"

What gene contains your sequence?

What disease is caused by a defect in this gene? If you don't know, put in OMIM.


6. Copy some of the above gene into Webcutter.


Generate a restriction enzyme map showing all the enzyme cut sites in the sequence.


Name an enzyme that might be used to cut out a small piece of your gene.