Macromolecules

Question

If 14C- labeled uracil is added to the growth medium of cells, what macromolecules will be labeled?

please explain answer.

Answer 1

Hi Brie!

To tackle this question, we have to work backwards.

Which macromolecules use nucleotides like thiamine, adenine, uracil?

Nucleic acids!

Then we have to remember that uracil is a funky case. Nucleic acids can be used to make either RNA or DNA, but only RNA uses uracil. Best as I understand, RNA needs to be slightly more unstable than DNA to help make equally funky shapes to facilitate its more random functions in the body (e.g. transporting stuff, making ribosomes—thank you PubMed https://pmc.ncbi.nlm.nih.gov/articles/PMC2732909/).

So uracil instead of thymine (AU,GC) in RNA, and thymine in DNA (AT, GC). I remember this difference by thinking: Thymine is Tough (slightly stronger for DNA).