# RNA --- **Ribonucleic acid**, or **RNA**, is a [[nucleic acid]] that carries out several specialized functions within the cell. It is a polymer of [[nucleotide]] monomers. Unlike [[DNA]], it is comprised only of a *single strand*. Still, this strand can have much more varience in the structure it can form, such as being able to bind with itself, form loops. Even if it does so, like DNA each strand is anti-parallel. RNA perform diverse functions. It can even act as an [[enzyme]]. The [[nucleotide|nucleotides]] that make it up are: guanine, adenine, cytosine and uracil (not thymine!). RNA can be very versatile, and it can take on different functions and roles. Name | Role ---|--- [[mRNA]] | runs "[[translation\|messages]]" between [[DNA]] and [[ribosome|ribosomes]] [[tRNA]] | transfers the [[codon\|codons]] on the mRNA into amino acids [[ribosome#Structure\|rRNA]] | makes up part of [[ribosome]], along with proteins [[CRISPR\|crRNA]] | bacterial copies of virus DNA ## RNA World Hypothesis The **RNA world hypothesis** is a widely held hypothesis that states that RNA [[chemical evolution|developed]] *before* [[DNA]] as self-replicating molecule for storing genetic information. It's much simpler, and it's relative instability would allow for early rapid evolutionary changes. Under this theory the need for a more stable method of information storage would have allowed DNA to develop to the double-helix we know and love. ![[RNA world.png]] Something else to consider in the RNA world hypothesis is that this may be how we first got [[evolution of viruses#The Virus-First Hypothesis|viruses]]. ___