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Levene and Chargaff. Milumbe Hamweetwa Abduallah Albaghjati. Prior Knowledge. DNA was located in the nucleus of every cell Composed of two bases: pyrimidines (T,C) and purines (A,G) Experimental designs involving UV light and chromatography paper were discovered.

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Levene and chargaff

Levene and Chargaff

Milumbe Hamweetwa

Abduallah Albaghjati

Prior knowledge
Prior Knowledge

  • DNA was located in the nucleus of every cell

  • Composed of two bases: pyrimidines (T,C) and purines (A,G)

  • Experimental designs involving UV light and chromatography paper were discovered

Levene experimental design
Levene Experimental Design

  • Analyzed the components of RNA molecule

  • Studied RNA because DNA is alkali resistant

  • Used alkali to hydrolyze nucleic acid

  • He found it contained four nitrogenous bases: cytosine, thymine, adenine, and guanine; deoxyribose sugar; and a phosphate group

Levene s conclusion
Levene’s Conclusion

  • Basic unit (nucleotide) was composed of a base attached to a sugar and that the phosphate also attached to the sugar. 

  • He (unfortunately) also concluded that the proportions of bases were equal and that there was a tetra nucleotide that was the repeating structure of the molecule.

  • Sugars were furanose rings (A furanose ring structure consists of four carbon and one oxygen atom with the anomeric carbon to the right of the oxygen.)

Chargaff experimental design
Chargaff Experimental Design

  • After taking out the nucleus from a cell, he extracted the DNA and decomposed it into its purine and pyrimidine subunits

  • By using chromotogrpahy paper, Chargaff was able to separate the purines and pyrimidines

  • Then shined UV light on the paper E

  • Since each base absorbs a different wavelength of light, he was able to find how much of each base was present

Chargaff s conclusions chargaff s rules
Chargaff’s Conclusions: Chargaff’s Rules

  • Amounts of adenine & guanine and thymine & cytosine differ between species

  • Discovered that in the DNA of organisms:

  • The amount of cytosine is equal to the amount of guanine

  • The amount of thymine is equal to the amount of adenine

Originally taken from: Creation Theory


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