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Unformatted text preview: Each nucleotide that is added to a growing DNA strand comes from a nucleoside triphosphate, a nucleoside (a nitrogenous base and a deoxyribose sugar) and a triphosphate tail. o ATP is a nucleoside triphosphate with ribose instead of deoxyribose. o Like ATP, the triphosphate monomers used for DNA synthesis are chemically reactive, partly because their triphosphate tails have an unstable cluster of negative charge. As each nucleotide is added to the growing end of a DNA strand, the last two phosphate groups are hydrolyzed to form pyrophosphate. o The exergonic hydrolysis of pyrophosphate to two inorganic phosphate molecules drives the polymerization of the nucleotide to the new strand. o The strands in the double helix are antiparallel. The sugar-phosphate backbones run in opposite directions. o Each DNA strand has a 3 end with a free hydroxyl group attached to deoxyribose and a 5 end with a free phosphate group attached to deoxyribose....
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