Genetics and Genomics

How did scientists discover DNA's existence?
Answered by Discovery Channel
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    Discovery Channel

  1. It took a number of scientists nearly 100 years to figure out what DNA was and how it worked. The first link in the process was Friedrich Miescher, a Swiss biologist who discovered an isolated compound in 1868. Miescher, who came from a line of scientists, had studied medicine, but had a hearing problem. He was concerned that his deafness would be a challenge in working as a physician and chose chemistry instead [source: Cracking the Code]. Miescher was able to pull DNA out of pus cells on bandages, and called the compound nuclein. Miescher thought that the acids, later named nucleic acid (the "NA" in deoxyribonucleic acid, or DNA), might include genetic coding, but he couldn't prove it. Miescher's discovery followed the work of Gregor Mendel, a Czech monk, who had completed a number of experiments with peas that showed how traits passed from one line of peas to another in "packages." We now call Mendel's packages genes [source:].

    William Astbury produced X-ray diffraction patterns in 1937 to show the irregular structure of DNA for the first time [source: Medical News]. A 1940s experiment confirmed DNA's role in carrying genetic information when Oswald Avery, Colin MacLeod and Maclyn McCarty figured out that DNA from the bacterium Streptococcus pneumonia could turn noncontagious bacteria into contagious bacteria. The experiment by Avery and his colleagues had moved nucleic acid and proved that genes were made of nucleic acids.

    Solving the complete mystery of DNA and its structure took some time and attention. Nine years after Avery, MacLeod and McCarty had demonstrated DNA in genes, Alfred Hershey and Martha Chase found more evidence to support Avery's discovery. One year later, James D. Watson and Francis Crick figured out the double helix structure of DNA. Watson and Crick had tried to work out a three-helical model, but had a flawed theory. Scientist Linus Pauling wanted to solve the mystery and became a Nobel Laureate in chemistry in 1954 after publishing a paper that proposed a triple-helical structure for DNA [source:]. Most importantly, the base pairing, as proposed by the models of Watson and Crick, made the important breakthrough of demonstrating how genetic material passes from generation to generation.

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