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A single DNA strand is a polymer of nuleotides. Each nucleotide is composed of a sugar (deoxyribose), a phosphate group, and a nitrogen base (adenine, guanine, cytosine, or thymine). Thousands of these four nucleotides ar bonded together in a linear strand. Two DNA stands then hydrogen bond and twist together to form a double helix. During the process of semiconservative replication, the DNA strands seperate and serve as templates so that the new DNA strands can be created by the enzyme DNA polymerase. |