mindbites.com Professor Wolfe explains the history behind the discovery of the strucutre of DNA. Molecules are too small to observe, and this means it was impossible to determine the molecular structure of DNA. In 1950, Franklin and Wilkins used X-ray defraction to create images of DNA, exposing a possible helical structure. They also determined 3 repetitive ratios, 0.34, 3.4, and 2.0, but did not know what these represented. This information was used by Watson and Crick to develop the first accurate approximation of the structure of DNA. They began with the belief that the structure was a double-helix and used molecular models, to piece together the structure. Watson and Crick discovered that the 0.34 nm number was the distance between each nucleotide, and the 3.4 nm number was 10 nucleotides. The 2.0 nm number they determined to be the diameter of the helix. They also discovered that purines and pyrimidines created a hydrogen bond across the double-helix. Using these dimensions and information, they created the model of DNA that has become the foundation for molecular genetics. Taught by Professor George Wolfe, this lesson was selected from a broader, comprehensive course, Biology. This course and others are available from Thinkwell, Inc. The full course can be found at www.thinkwell.com The full course covers evolution, ecology, inorganic and organic chemistry, cell biology, respiration, molecular genetics, photosynthesis, biotechnology, cell reproduction, Mendelian …
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this is for my ap biology extra credit assignment, sorry for being a bad singer but i hope you like it! This is for my extra credit project, in ap bio, this is the first unit. really sorry for being a bad singer. this is to the tune of one of the songs in spring awakening. Lyrics: Well i dreamed there was an angle who could help with the chem of life cause all my friends have a’s and i want to be a smart wife help me out-out of this nightmare than i heard her silver call she said: first thing you should know is that carbon is it all also the 3 types of bonds are covalent ionic and hydrogen cause and atom has nueutrons, protons, and electrons that make you grin and a molecule is 2 or more atoms with a bond with electronegativity to make the bond strong cause hydrogens the weakest and theres 2 types of covalent bonds holding all of life together so our life can move on see waters so amazing its a solvent with a high surface tension and its adhesion helps it go up plants by capillary action ice floats, and water has a high heat capacity i mean, please cant you see waters amazing abilities organic molecules have carbon with the big ones as macromolecules which are mostly polymers made of monomers why do we need to know this— no one knows see theres 4 important classes carbohydrates proteins and lipids and you cant forget nucleic acids cause everyone needs it glucose fructose galactose are some monosaccharides and sucrose lactose maltose are some disaccharides cause 2 …
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