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RNA
(abbreviation for ribonucleic acid)
Nucleic acid involved in the process of translating the
genetic material DNA into proteins. It is usually single-stranded,
unlike the double-stranded DNA, and consists of a large number of
nucleotides
strung together, each of which comprises the sugar ribose, a phosphate group, and one of
four bases (uracil, cytosine, adenine, or guanine). RNA is copied
from DNA by the formation of base pairs,
with
uracil taking the place of thymine. RNA occurs in three major forms, each with a different
function in the synthesis of protein molecules. Messenger RNA (mRNA)
acts as the template for protein
synthesis. Each codon (a set of threebases) on the RNA molecule
is matched up with the corresponding amino acid, in accordance with the genetic code. This process (translation) takes place in the
ribosomes, which are made up of proteins and ribosomal RNA (rRNA). Transfer RNA (tRNA) is
responsible for combining with specific amino acids, and then matching up a special
`anticodon´
sequence of its own with a codon on the mRNA. This is how the genetic code is translated.
Although RNA is normally associated only with the process of protein synthesis, it makes
up the hereditary material itself in some viruses, such as retroviruses.
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The
Kallisto Effect