Transcript History of DNA Discovery

History of DNA Discovery
CH 11 Section 1
History of DNA Discovery
► British
biologist Frederick Griffith discovered
“transforming factor” when doing an
experiment w/ bacterial pneumonia on mice
in 1928. (p. 226)
► American scientist Oswald Avery conducted
experiments that showed DNA had to be the
“transforming factor” (p. 227)
► Alfred Hershey & Martha Chase conducted a
series of experiments using bacteriphages
to help solidify that DNA must carry genetic
information. (p. 228)
►
Griffith showed that although a deadly strain of bacteria could be made
harmless by heating it, some factor in that strain is still able to change other
harmless bacteria into deadly ones. He called this the "transforming factor."
►
Hershey and Chase offered further evidence that DNA, not proteins, is the
genetic material. Only the DNA of the old generation of viruses is incorporated
into the new generation.
Concept Check 11.1
1.
How did Griffith's experiments indicate the presence of a
"transforming factor" in bacteria?
2.
What did Avery's experiments add to the knowledge gained from
Griffith's experiments?
3.
Describe the experimental design that allowed Hershey and Chase to
distinguish between the two options for genetic material.