Exam 2: Chemistry of Life

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Nucleic acids are macromolecules that are essential for the storage and expression of genetic information in living organisms. They are composed of nucleotides, which consist of a sugar molecule (either ribose in RNA or deoxyribose in DNA), a phosphate group, and a nitrogenous base (adenine, guanine, cytosine, or thymine in DNA, and uracil in RNA).

The structure of a nucleic acid is a long chain of nucleotides linked together by phosphodiester bonds between the sugar and phosphate groups. The nitrogenous bases extend from the sugar-phosphate backbone and form hydrogen bonds with complementary bases on the opposite strand, creating the characteristic double helix structure in DNA.

RNA and DNA have several key differences. DNA is typically double-stranded, while RNA is usually single-stranded. DNA contains the nitrogenous base thymine, while RNA contains uracil instead. The sugar in DNA is deoxyribose, while in RNA it is ribose. Additionally, DNA is primarily found in the cell nucleus, where it stores genetic information, while RNA is involved in various cellular processes such as protein synthesis and can be found in the nucleus as well as the cytoplasm. These differences in structure and function allow DNA and RNA to perform distinct roles in the cell.