Watch this lecture to review the structure of DNA. All of the 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.
Source: Khan Academy, https://youtu.be/AmOO4j0E408
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 License.