General Index


RNA

Transfer RNA, tRNA

tRNA is the molecule that activates aminoacids for their entry in the protein synthesis system. It is a small nucleic acid (75-90 residues) and associates the aminoacid with its genetic code, thus being a translator molecule. The tRNASer, that is, the tRNA in charge of activating the aminoacid Serine:

This molecule is the tRNASer from the yeast Saccharomyces cerevisiae. Due to the degeneracy of the Genetic Code, it is possible to find in the cell several tRNAs able to activate serine (Isoacceptor tRNAs). It is a small molecule (85 nucleotides) whose general structure is that of a L. This form results from the folding in space of the "cloverleaf" model. The two branches of the L are the following:

One is the Acceptor Stem, because it contains the site of union of the aminoacid (at the 3'-end):

It is a single polynucleotide that can be coloured by the group pattern, in a way that the 5'-end appears in blue and the 3' in red, with all the intermediate color scale.



Ribosomal RNA, rRNA

We present the structure of 5s rRNA. It is a ribopolynucleotide of 118 residues in length. It has also autocomplementary regions, as in tRNA:

5s rRNA is one of the two molecules of rRNA that form part of the large ribosomal subunit (50s in Prokaryota and 60s in Eukaryota).



Other RNAs

We present the structure of two Ribozymes, that is, ribonucleic acid molecules with catalytic (enzymatic) activity.

One is a small ribozyme, an example of the so-called Hammerhead Ribozymes:

Other is a ribozyme from Tetrahymena, whose function has to do with Intron Splicing:

It is formed by two polynucleotides of 414 residues each:


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