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As with DNA, RNAs can exist in single-stranded (annotated "ssRNA") or double-stranded ("dsRNA") forms; however, the vast majority of cellular RNAs are single-stranded. dsRNAs generally function in post-transcriptional [[gene regulation]] or as viral genetic material. Targeted degradation of dsRNAs is a major intracellular defence mechanism against viruses.
As with DNA, RNAs can exist in single-stranded (annotated "ssRNA") or double-stranded ("dsRNA") forms; however, the vast majority of cellular RNAs are single-stranded. dsRNAs generally function in post-transcriptional [[gene regulation]] or as viral genetic material. Targeted degradation of dsRNAs is a major intracellular defence mechanism against viruses.
==Structure==
Every nucleotide of RNA consists of a ribose molecule with a nitrogenous base attached to its 1' carbon and a phosphate group attached to its 5' carbon. Individual RNA nucleotides are linked by a [[phosphodiester bond]] between the 3' carbon of one nucleotide's ribose and the 5' carbon on the next.
The four nitrogenous bases used in RNA are [[adenine]], [[guanine]], [[cytosine]], and [[uracil]]. Adenine and guanine are the ''purine'' bases, cytosine and uracil are the ''pyrimidine'' bases. Like in DNA, these bases can hybridize through [[hydrogen bond|hydrogen bonds]]; adenine hybridizes with uracil and guanine hybridizes cytosine.
Hybridization of nucleotides within RNA molecules allows for the formation of ''secondary structures'' such as RNA hairpins, these secondary structures give RNA molecules an overall ''tertiary structure'' which is often essential for the RNA to perform its function. Additionally, RNAs can hybridize through base pairing with other RNAs or with complementary DNA sequences.
==References==
==References==