202409212356 Status: #article Tags: Title: RNA (Wikipedia) Author: ---- # RNA (Wikipedia) ## What Kind of Article Practical / Expository ## Summary ## Outline - RNA is a molecule that is essential for most biological functions. It comes in two broad types: - Non-coding RNA: performs functions itself - Messenger RNA (mRNA): provides a template for the production of proteins - Transfer RNA (tRNA) molecules deliver amino acids to the ribosome, where ribosomal RNA (rRNA) then links amino acids together to form coded proteins - The chemical structure of RNA is very similar to that of DNA, but differs in three primary ways: - Unlike double-stranded DNA, RNA is usually a single-stranded molecule in many of its biological roles and consists of much shorter chains of nucleotides. However, [double-stranded RNA](https://en.wikipedia.org/wiki/RNA#Double-stranded_RNA) (dsRNA) can form and (moreover) a single RNA molecule can, by complementary base pairing, form intrastrand double helixes, as in [tRNA](https://en.wikipedia.org/wiki/Transfer_RNA "Transfer RNA"). - While the sugar-phosphate "backbone" of DNA contains _[deoxyribose](https://en.wikipedia.org/wiki/Deoxyribose "Deoxyribose")_, RNA contains _[ribose](https://en.wikipedia.org/wiki/Ribose "Ribose")_ instead. Ribose has a [hydroxyl](https://en.wikipedia.org/wiki/Hydroxy_group "Hydroxy group") group attached to the pentose ring in the [2'](https://en.wikipedia.org/wiki/Nucleic_acid_nomenclature "Nucleic acid nomenclature") position, whereas deoxyribose does not. The hydroxyl groups in the ribose backbone make RNA more chemically [labile](https://en.wikipedia.org/wiki/Lability "Lability") (i.e. more easily changeable or reactive) than DNA by lowering the [activation energy](https://en.wikipedia.org/wiki/Activation_energy "Activation energy") of [hydrolysis](https://en.wikipedia.org/wiki/Hydrolysis "Hydrolysis"). - The complementary base to [adenine](https://en.wikipedia.org/wiki/Adenine "Adenine") in DNA is [thymine](https://en.wikipedia.org/wiki/Thymine "Thymine"), whereas in RNA, it is [uracil](https://en.wikipedia.org/wiki/Uracil "Uracil"), which is an [unmethylated](https://en.wikipedia.org/wiki/Methylation "Methylation") form of thymine. - Like DNA, most biologically active RNAs, including [mRNA](https://en.wikipedia.org/wiki/MRNA "MRNA"), [tRNA](https://en.wikipedia.org/wiki/TRNA "TRNA"), [rRNA](https://en.wikipedia.org/wiki/RRNA "RRNA"), [snRNAs](https://en.wikipedia.org/wiki/SnRNA "SnRNA"), and other [non-coding RNAs](https://en.wikipedia.org/wiki/Non-coding_RNA "Non-coding RNA"), contain self-complementary sequences that allow parts of the RNA to fold and pair with itself to form double helices. Analysis of these RNAs has revealed that they are highly structured. Unlike DNA, their structures do not consist of long double helices, but rather collections of short helices packed together into structures akin to proteins. - The functional form of single-stranded RNA molecules, just like proteins, frequently requires a specific [tertiary structure](https://en.wikipedia.org/wiki/RNA_Tertiary_Structure "RNA Tertiary Structure"). The scaffold for this structure is provided by [secondary structural](https://en.wikipedia.org/wiki/Secondary_structure "Secondary structure") elements that are hydrogen bonds within the molecule. - About 97% of transcriptional output (i.e. DNA to RNA transcription) results in non-protein-coding RNA in eukaryotes. These are all types of RNA *aside from* mRNA (which carries information from DNA to the ribosome for protein production) ## Thoughts & Ideas ## Criticisms --- # References