DNA

Watch this lecture to review the structure of DNA. All nucleotides in DNA are made of the same basic parts: deoxyribose sugar molecules and nitrogenous bases (the purines: adenine and guanine, and the pyrimidines: thymine and cytosine). Adenine pairs with thymine, and guanine pairs with cytosine. After you finish this section, you should be able to create complementary base pairs on a DNA strand.