Lecture.15.Fall.2013(1)

Genomes encode 30 to 40 different trnas trna

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Unformatted text preview: e language of protein Each tRNA attaches to a single type of amino acid Most genomes encode 30 to 40 different tRNAs tRNA structure Cloverleaf structure, due to intramolecular base-pairing The tRNA is “charged” with an amino acid via an ester bond at the 3’ end The anticodon is complimentary to the codon specifying that amino acid As always, base-pairing is antiparallel Features of tRNAs Secondary and tertiary structure (see previous slide) Lots of rare, modified bases: ribothymine, pseudouridine, dozens of others These aren’t encoded in DNA; where do they come from? tRNA-modifying enzymes tRNA gene structure and processing Prokaryotic: often clusters of tRNAs are transcribed together and then cut apart; individual tRNAs are then trimmed and modified bases are created Eukaryotic: individual tRNA precursors are transcribed, then trimmed down to the correct sequence Often an intron must be removed (via an enzymatic process) Bases are added to the 3’ end, and other bases are modified rRNA structure and processing rRNAs (ribosomal RNAs) comprise 80% of the RNA in a cell Bacterial ribosomes contain 3 rRNA molecules, while eukaryotic ribosomes contain 4 rRNA gene...
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This document was uploaded on 02/25/2014.

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