Why do ribosomes and tRNA contain so much RNA?

[horsebox]

Firstly the ribosome. I know its the site that the mRNA binds to while the tRNA brings in the amino acids but why is it composed of so much RNA? I thought RNA was only really an information encoding molecule.

Also I read there that tRNA consists of around 70 nucleotide bases. If each tRNA molecule only uses 3 bases to recognize a specific codon why does it need 70 bases?

 

[Hercules Rockefeller]

Firstly the ribosome. I know its the site that the mRNA binds to while the tRNA brings in the amino acids but why is it composed of so much RNA?

The rRNA plays an integral role in the ribosome by binding to the mRNA and providing peptidyl transferase activity that links amino acids together.

I thought RNA was only really an information encoding molecule.

Absolutely not! There are quite a few classes of non-coding RNAs (ncRNAs). A huge amount of genetics research effort these days is directed at studying ncRNAs, and their biological and physiological importance has really only been appreciated recently.

Also I read there that tRNA consists of around 70 nucleotide bases. If each tRNA molecule only uses 3 bases to recognize a specific codon why does it need 70 bases?

You have to remember to think of biology as 3D interactions. Molecules evolve to have 3D shapes that provide specificity in their interactions with other molecules that do, or do not, have the required 3D grooves and bulges for interaction.

 

[horsebox]

Thanks. As for research into ncRNAs, thats interesting shit. Genetics I find is one of the more fascinating fields in science. It reminds me a lot of programming.