Before knowledge of DNA, how did we explain how traits are passed on from parent to offspring?
a lesson in progress… Frederick Griffith (British, 1928): – Wanted to find out how/why certain bacteria make you sick
What was Griffith’s grand conclusion? Griffith performed what he called transformation, a term still used today
Step 2… Oswald Avery (1944, Canadian) used enzymes to break down the primary components (lipids, nucleic acids, proteins, carbohydrates) of the bacteria cells in Griffith’s experiment to determine which component was exchanging information. – Results: Griffith’s process did not work when Avery used enzymes to breakdown the nucleic acid of the deadly bacteria
Hershey–Chase experiment: a verification of Avery Alfred Hershey and Martha Chase (American, 1952) – Conclusion?
Rosalind Franklin (50’s British) and the first image of DNA Used x-ray diffraction to get this image What hints about the structure can be gained from this?
Chargaff’s Rules and the first insight into how DNA works American biochemist Erwin Chargaff isolated molecules from DNA in the following proportions: Conclusion? http://www.dnalc.org/resources/3d/21-chargaff-ratios.html % of Nitrogenous bases AGCT Octopus33.217.6 31.6 Chicken28.022.021.628.4 Rat28.621.420.528.4 Human29.320.720.030.0
The grand conclusion James Watson (British physicist) and Francis Crick (American biologist) 1953: DNA is a….DOUBLE HELIX
DNA’s specifications Width: 2 nanometer (nm), or 2 billionths of a meter Length (per cell): 1 m – How does it all fit in one cell? How much total length of DNA in one human? – How far is that?
Where does DNA live? Click on the following link for a “journey into DNA.” http://www.pbs.org/wgbh/nova/genome/dna.html#
List the ways form and function fulfilled. Watch the replication of DNA: – http://www.hhmi.org/biointeractive/dna/animati ons.html (technical) http://www.hhmi.org/biointeractive/dna/animati ons.html – http://www.teachersdomain.org/asset/tdc02_vid _dnaanimation/ http://www.teachersdomain.org/asset/tdc02_vid _dnaanimation/ – http://www.pbs.org/wgbh/aso/tryit/dna/shockwa ve.html (replication workshop, Shockwave activity) http://www.pbs.org/wgbh/aso/tryit/dna/shockwa ve.html – http://www.youtube.com/watch?v=OnuspQG0Jd0&safe=active (technical, but good) http://www.youtube.com/watch?v=OnuspQG0Jd0&safe=active