核糖核酸RNA

核糖 2′ 位的羟基使 RNA 比 DNA 更易水解，也让它能形成更多样的结构。单链内部互补区段配对形成茎环、假结等二级结构。信使 RNA（mRNA）携带蛋白质编码信息；转运 RNA（tRNA）呈三叶草形，把氨基酸运到核糖体；核糖体 RNA（rRNA）构成核糖体并催化肽键形成。此外还有 microRNA、siRNA、长链非编码 RNA 等调控 RNA。

The 2′-hydroxyl on ribose makes RNA easier to hydrolyse than DNA and lets it adopt more varied structures. Complementary stretches within one strand pair into stem-loops, pseudoknots and other secondary structures. Messenger RNA (mRNA) carries protein-coding information; cloverleaf-shaped transfer RNA (tRNA) brings amino acids to the ribosome; ribosomal RNA (rRNA) forms the ribosome and catalyses peptide-bond formation. There are also regulatory RNAs such as microRNA, siRNA and long non-coding RNA.

1961 年布伦纳、雅各布和梅塞尔森证实了 mRNA 的存在；同年尼伦伯格和马太用人工合成的 poly(U) 破译了第一个密码子。1965 年霍利测定了第一个 tRNA 的序列。1982 年切赫和 1983 年奥尔特曼发现 RNA 具有催化活性（核酶），获 1989 年诺贝尔化学奖。2000 年核糖体结构解析证明其催化中心完全由 RNA 构成。

In 1961 Brenner, Jacob and Meselson confirmed the existence of mRNA, and Nirenberg and Matthaei used synthetic poly(U) to crack the first codon. Holley sequenced the first tRNA in 1965. Cech (1982) and Altman (1983) discovered that RNA can catalyse reactions (ribozymes) and shared the 1989 Nobel Prize in Chemistry. Ribosome structures solved in 2000 showed that its catalytic centre is made entirely of RNA.

RNA 干扰（2006 年诺贝尔生理学或医学奖）用于基因沉默研究和药物开发；mRNA 疫苗通过核苷修饰（如以假尿苷 Ψ 替代尿苷）降低免疫原性，卡里科和韦斯曼因此获 2023 年诺贝尔生理学或医学奖。CRISPR 系统依靠向导 RNA 定位目标 DNA。RNA 世界假说认为早期生命以 RNA 同时承担遗传与催化功能。

RNA interference (Nobel Prize in Physiology or Medicine 2006) is used to silence genes in research and drug development; mRNA vaccines use modified nucleosides such as pseudouridine to reduce immunogenicity, for which Karikó and Weissman received the 2023 Nobel Prize in Physiology or Medicine. CRISPR systems use guide RNA to find target DNA. The RNA-world hypothesis proposes that early life used RNA for both heredity and catalysis.