An extinct language is the term for a language no longer spoken
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>
The cytoplasm of prokaryotic cells also houses the ribosomes required for the manufacture of protein. There can be many ribosomes in the cytoplasm. For example, a rapidly growing bacterium can contain upwards of 15,000 ribosomes.
The segments of the DNA that are transcribed into mRNA and are used to produce amino acids are called EXONS. This segments are coding regions. In the transcription process, the non-coding regions are removed and the only segments that remain are the coding regions. The exons are used to produce amino acids.
