â€¢ Acid hydrolysis of DNA extracts trace amounts of pentoses (deoxyribose), purine bases (A & G), and proteins from DNA = good way to separate DNA into its components
â€¢ Base hydrolysis of DNA cannot extract any of the components being tested.
â€¢ Unhydrolyzed DNA : negative for all except for Xanthoproteic test and test for inorganic Pi
â€¢ Acid hydrolysis of RNA extracts trace amounts of reducing sugars, pentoses, purine bases, proteins, and phosphoric acid.
â€¢ Base hydrolysis of RNA extracts pentoses, purine bases, proteins, and phosphoric acid.
â€¢ Unhydrolyzed RNA positive for all test except presence of C & T; and A & G = best way to separate RNA into its components.
â€¢ Sample extracted from yeast contains RNA, but impure.
2. Based on the qualitative tests, how can you differentiate hydrolyzed from unhydrolyzed RNA?
â€¢ Unhydrolyzed RNA: positive for all except for the presence of uracil and cytosine
ïƒ˜ Pentoses, purine(A & G) and pyrimidine bases, proteins, and phosphoric acid were extracted
ïƒ˜ No uracil
ïƒ˜ Acid-hydrolyzed RNA:
ïƒ˜ Trace amounts of reducing sugars, pentoses, purine(A & G) and pyrimidine bases, Phe, Tyr, Trp, and phosphoric acid
ïƒ˜ No tri- and polypeptides
ïƒ˜ Base-hydrolyzed RNA
ïƒ˜ pentoses, purine(A & G) and pyrimidine bases, tri- and polypeptides, Phe, Tyr, Trp, and phosphoric acid
ïƒ˜ 0.05% NaOH is the best reagent to separate RNA into its components
3. Based on these experimental results, do you think you obtained pure RNA from yeast? Why or why not?
â€¢ We obtained impure RNA from yeast
ïƒ˜ Pentoses present : RNA and/or DNA
ïƒ˜ Deoxyribose not present : RNA
ïƒ˜ Uracil and Thymine : not present
ïƒ˜ Purine bases are present
ïƒ˜ Presence of tri- and polypeptides = impurities