{"id":18941,"date":"2022-10-22T05:00:43","date_gmt":"2022-10-22T03:00:43","guid":{"rendered":"https:\/\/www.sciencefocus.com\/?p=129775"},"modified":"2022-10-22T05:20:18","modified_gmt":"2022-10-22T03:20:18","slug":"rna-what-it-is-what-it-does-and-why-its-one-of-lifes-most-important-molecules","status":"publish","type":"rss_feed","link":"https:\/\/c01.purpledshub.com\/bbcsciencefocus\/rss_feed\/rna-what-it-is-what-it-does-and-why-its-one-of-lifes-most-important-molecules\/","title":{"rendered":"RNA: What it is, what it does, and why it\u2019s one of life\u2019s most important molecules"},"content":{"rendered":"

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By JV Chamary\n \t\t<\/p>

Published: Saturday, 22 October 2022 at 12:00 am<\/p>

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What is RNA made of?<\/h2>\n
Like its more famous chemical cousin, deoxyribonucleic acid (DNA<\/a>), ribonucleic acid (RNA) is a nucleic acid \u2013 a molecule assembled from a chain of building blocks called nucleotides. In terms of composition, each nucleotide comes with one chemical letter or \u2018base\u2019:<\/p>\n
Adenine (A)<\/li>\n
Cytosine (C)<\/li>\n
Guanine (G)<\/li>\n
Thymine (T)<\/li>\n
Uracil (U)<\/li>\n<\/ul>
Although both forms of nucleic acid use a four-letter alphabet that includes A, C and G, DNA uses T, whereas RNA uses U.<\/p>\n
However, it\u2019s a relatively trivial difference, as T and U are read as equivalent bases, like capital and lowercase versions of the same letter.<\/p>\n
RNA is often a standalone chain. However, in complex cells, DNA strands are arranged as chromosomes<\/a>: they\u2019re wrapped around large histone proteins, like thread wound around a spool. That arrangement is possible because, with millions of letters, DNA is generally several orders of magnitude longer<\/em> than RNA.<\/p>\n
The shortest RNAs are microRNA and small-interfering RNA<\/a>, at just 20-30 nucleotides in size, and the longest RNA in humans is a copy of the titin gene, at 109,224 letters long.<\/p>\n
What does RNA do?<\/h2>\n
RNA carries biological information. DNA\u2019s function is to store information in the genome \u2013 the book of life, or instruction manual for creating an organism.<\/p>\n
RNA, on the other hand, plays various roles that influence how genes (DNA\u2019s instructions) are read, which determines characteristics like observable features and physiology.<\/p>\n
The human genome<\/a> contains over 6 billion letters, but only around 1 per cent of DNA encodes genes for making proteins \u2013 the molecules that perform the majority of tasks, such as working as the enzymes (biological catalysts) that trigger the chemical reactions that sustain life.<\/p>\n
The remaining 99 per cent is non-coding: most is harmless \u2018junk DNA\u2019 but some are genes whose end product is RNA itself.<\/p>\n
Read more about DNA:\u00a0<\/strong><\/p>\n
Everything you need to know about DNA (almost)<\/a><\/li>\n
Quantum weirdness could be the driving force behind DNA mutations<\/a><\/li>\n
The DNA Detective: How to solve family mysteries with ancestry testing<\/a><\/li>\n<\/ul>
What\u2019s the difference between RNA and DNA?<\/h2>\n
RNA is \u2018ribonucleic acid\u2019 and DNA is \u2018deoxyribonucleic acid\u2019.<\/p>\n
The two forms of nucleic acid<\/a> have similar backbones, which consist of two alternating chemical groups: phosphate and a sugar, ribose. The sugars in DNA\u2019s backbone are missing a hydroxyl group (hydrogen plus oxygen), turning ribose into deoxyribose.<\/p>\n
This tiny difference has a huge impact on chemistry: with its more reactive ribose sugar, RNA is more likely to react with other molecules \u2013 and even itself.<\/p>\n
The two nucleic acids also differ in structure. While RNA is typically a single-stranded molecule, DNA forms the iconic double helix \u2013 dual strands that spiral around one another like a twisted ladder.<\/p>\n
The ladder\u2019s rungs represent hydrogen bonds \u2013 electrostatic attractions that link complementary letters on opposite strands into pairs: A with T, C with G. That base pairing occurs all the way along DNA, holding its strands together, like teeth on two halves of a zipper.<\/p>\n
Unlike DNA, RNA doesn\u2019t usually exist as one long double-stranded molecule, but as a solitary strand. And yet, complementary letters from separate sections of an RNA strand can pair together (\u2018AAAA\u2019 matching \u2018UUUU\u2019, for example), which forms double-stranded regions called stems.<\/p>\n
Such pairing doesn\u2019t occur at every point in the molecule, however, and many sections remain single-stranded. Overall, an RNA will often include structures known as \u2018hairpin loops\u2019<\/a>. RNA can sometimes pair with DNA, but the size difference means full DNA-RNA hybrids don\u2019t occur.<\/p>\n
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What\u2019s the difference between RNA and DNA?<\/h2>\nRNA is \u2018ribonucleic acid\u2019 and DNA is \u2018deoxyribonucleic acid\u2019.<\/p>\n