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Tumbaga, Nesty Margarretta M. Date Performed: September 01, 2010

Bustamante, Sofia Anne G. Date Submitted: September 08, 2010

Experiment No. 09

Hydrolysis of Nucleic Acids


Twelve samples consisting of extracted and standard DNA and RNA were prepared. Eight of them were hydrolyzed using 1.0 M HCl and 3.0 NaOH; they were heated in boiling water for one hour. The remaining four were et aside to be used as negative controls. The obtained hydrosylates and control were subjected to tests for Pentoses and Purines. Test tubes containing standard DNA were positive for pentoses. However, this is not in accord with the expected theoretical result. Meanwhile, test for purines was quite successful. Test tubes hydrolyzed with strong acids showed positive results. However, the negative controls also formed white precipitate, while the remaining samples showed red-brown precipitate. The observed deviations from theoretical results are all attributed to sample contamination or degradation.

Results and Discussion:

Figure 1. RNA and DNA components [4]

Nucleotides are nucleic acid polymers. They consist of purine or pyrimidine bases that are attached to a ribose unit. At least one phosphate group is attached to C5' position of the ribose. RNA is made up of ribonucleotides whereas DNA is composed of deoxyribonucleotides. An OH group is present at the C2' position of ribonucleotides. It is substituted with H in deoxyribonucleotides.

Figure 2. Structure of DNA [2]

DNA consists of antiparallel chains of phophodiester bond that linked nucleotides. H-bonding form double stranded helix. The aromatic bases are planar and they form stacks. These stacks are parallel to the axis of the helix. The nitrogenous bases occupy the core of the helix whereas sugar-phosphate chains are exposed at the periphery of DNA. This minimizes repulsion between the negatively charged phosphate groups.

Figure 3. Structure of RNA [1]...