2010 National DNA Day Online Chatroom Transcript

This is just one question from an archive of the National DNA Day Moderated Chat held in April 2010. The NHGRI Director and many genomics experts from across NHGRI took questions from students, teachers and the general public on topics ranging from basic genomic research, to the genetic basis of disease, to ethical questions about genetic privacy.

632
How big is DNA?
     Barry Starr, Ph.D.: I run a program out of Stanford's Department of Genetics where I train science graduate students how to communicate science to the public. I do this by having the students run fun hands on genetics activities at The Tech Museum of Innovation in San Jose and by having them answer people's genetics questions online at our Understanding Genetics website. Fun question. Each cell of your body (except mature red blood cells) has 6 feet of DNA. All the DNA in your body would strewtch to the sun and back 60 times! The best estimate I could find of the worlds population of people is around 6.7 billion. When we multiply 10 billion miles of DNA by 6.7 billion, we end up with, well, a really big number. Something like 6.7 X 1019 or 67 quintillion miles. That is too big a number so lets convert this to light years. A light year is around 6 X 1012 miles. So all human DNA would stretch 11.2 million light years. The closest star to Earth (besides the sun) is around 4.2 light years. So we shoot way past that! The Andromeda galaxy is about 2.5 million light years away from us so human DNA could stretch there and back two or three times.
East Haven High School in CT (10th grade student)

< View ALL questions and answers from 2010



(short, single keywords work best at first)