a. In what ways are the structures of RNA and DNA alike, and in what ways are they different?

RNA and DNA are both nucleic acids, which are complex molecules that play crucial roles in cellular functions and processes. Here are some ways in which the structures of RNA and DNA are alike and different:

Similarities:

1. Both RNA and DNA are made up of monomers called nucleotides.
2. Both have a sugar-phosphate backbone.
3. Both use the bases adenine (A) and guanine (G).

Differences:

1. The sugar in RNA is ribose, while in DNA it is deoxyribose. Deoxyribose lacks one oxygen atom compared to ribose, hence the name "deoxy."
2. RNA uses the base uracil (U) in place of thymine (T), which is used in DNA.
3. DNA is typically double-stranded, forming a double helix, whereas RNA is typically single-stranded.
4. DNA is stable under alkaline conditions while RNA is not stable.
5. DNA is self-replicating, RNA is synthesized from DNA when needed.