The process of RNA editing is the alteration of the sequence of nucleotides in the RNA after it has been transcribed from DNA, but before it is translated into a protein. RNA editing occurs by two distinct mechanisms:<em><u /><u>Substitution</u> <u>editing </u></em>and <u><em>Insertion/</em></u><em></em><u><em>deletion</em></u><em> <u>editing</u></em>.
<u><em>Substitution editing</em></u> is the chemical alteration of individual nucleotides. These alterations are catalyzed by enzymes that recognize a specific target sequence of nucleotides:
*Cytidine Deaminases that convert a C in the RNA to uracil.
*<em />adenosine deaminases that convert an A to inosine,which the ribosome translates as a G.<span>Thus a CAG codon</span><span> (for Gln) can be converted to a CGG codon (for Arg).
<em><u>*Insertion/deletion editing</u></em><em><u /></em><u /> is the insertion or deletion of nucleotides in an RNA.
These alterations are mediated by guide RNA molecules that base-pair as best they can with the RNA to be edited and serve as a template for the addition( or removal) in the target.</span>
Answer:
all cells so the last one
