Short answers, pulled from the story.
RNA, or ribonucleic acid, is a polymeric molecule essential for most biological functions. It is assembled as a chain of nucleotides and either performs a function itself as non-coding RNA or serves as a template for protein production as messenger RNA. Nucleic acids like RNA and DNA are among the four major macromolecules essential for all known forms of life.
RNA differs from DNA in three primary ways. RNA is usually single-stranded with much shorter chains, its backbone sugar is ribose rather than deoxyribose with an extra hydroxyl group at the 2 prime position, and the complementary base to adenine is uracil instead of thymine. That 2 prime hydroxyl group makes RNA more chemically labile than DNA.
Three types of RNA carry out protein synthesis. Messenger RNA carries information from DNA to the ribosome, transfer RNA delivers specific amino acids using an anticodon region, and ribosomal RNA acts as the catalytic component that links amino acids together. Nearly all the RNA in a typical eukaryotic cell is ribosomal RNA.
The RNA world hypothesis proposes that early in the history of life on Earth, before DNA and possibly before protein-based enzymes, RNA served as both the storage method for genetic information and a catalyst for biochemical reactions. Carl Woese hypothesized in 1968 that RNA might be catalytic. The ribosome, a ribozyme whose active site is composed entirely of RNA, is cited as evidence.
RNA uses four bases, adenine, cytosine, guanine, and uracil, because four is the minimum needed to design any given secondary structure. Two or three bases would not be enough to create all structures, while more than four are not necessary. This is likely why nature chose a four-base alphabet.
RNA research has produced numerous Nobel Prizes. Robert W. Holley shared the 1968 prize for sequencing a yeast tRNA, Thomas Cech and Sidney Altman won in 1989 for catalytic RNA, Andrew Fire and Craig Mello won in 2006 for RNA interference, and Katalin Kariko and Drew Weissman won in 2023 for modified nucleosides that enabled mRNA vaccines against COVID-19.
mRNA vaccines use messenger RNA to manufacture proteins that provoke an immune response. They are thought to be easier to produce than traditional vaccines made from killed or altered pathogens. Their first successful large-scale application came as COVID-19 vaccines during the COVID-19 pandemic.