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Ribonucleic acid or RNA is a nucleic acid polymer consisting of nucleotide monomers that plays several important roles in the processes that translate genetic information from deoxyribonucleic acid (DNA) into protein products;

RNA acts as a messenger between DNA and the protein synthesis complexes known as ribosomes, forms vital portions of ribosomes, and acts as an essential carrier molecule for amino acids to be used in protein synthesis.

RNA is very similar to DNA, but differs in a few important structural details: RNA is single stranded, while DNA is double stranded.

Also, RNA nucleotides contain ribose sugars while DNA contains deoxyribose and RNA uses predominantly uracil instead of thymine present in DNA.

RNA is transcribed from DNA by enzymes called RNA polymerases and further processed by other enzymes.

RNA serves as the template for translation of genes into proteins, transferring amino acids to the ribosome to form proteins, and also translating the transcript into proteins.

RNA is a polymer with a ribose and phosphate backbone and four different bases: adenine, guanine, cytosine, and uracil.

The first three are the same as those found in DNA, but in RNA thymine is replaced by uracil as the base complementary to adenine.

This base is also a pyrimidine and is very similar to thymine.

Uracil is energetically less expensive to produce than thymine, which may account for its use in RNA.

In DNA, however, uracil is readily produced by chemical degradation of cytosine, so having thymine as the normal base makes detection and repair of such incipient mutations more efficient.

Thus, uracil is appropriate for RNA, where quantity is important but lifespan is not, whereas thymine is appropriate for DNA where maintaining sequence with high fidelity is more critical.

Note:   The above text is excerpted from the Wikipedia article "RNA", which has been released under the GNU Free Documentation License.
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October 13, 2015

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updated 12:56 pm ET