ypes of nitrogenous bases in DNA. They are (A)denine, (G)uanine, (T)hymine, (C)ytosine and they must be paired very specifically. Only Adenine with Thymine (A-T) and Guanine with Cytosine (G-C). To form a polynucleotide DNA, many nucleotides are linked together with 3`-5` phosphodiester linkages. In a complete molecule of DNA two of these polynucleotide strands are linked together by nitrogenous bases at 90 degrees to the sugar-phosphate "spine" (FIG. 1). The nitrogenous bases are held together with weak hydrogen bonds. One polynitrogenous chain runs in a 3'-5' direction, the 3' being the top hydroxyl and the 5' being the bottom phosphate attached to the carbon five of the sugar. The other string runs the opposite. The two strands of the structure cannot be identical but they are complimentary. There is no restrictions on the placement and sequence of the nucleotides, which becomes important in storage of information. TRANSCRIPTION: The Synthesis o
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