Basic Principles of Transcription and Translation - Computer ...
Basic Principles of Transcription and Translation - Computer ...
Basic Principles of Transcription and Translation - Computer ...
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Amino acid<br />
attachment site<br />
3′<br />
5′<br />
Anticodon<br />
(a) Two-dimensional structure<br />
Anticodon<br />
5′<br />
Hydrogen<br />
bonds<br />
3′<br />
Hydrogen<br />
bonds<br />
(b) Three-dimensional structure<br />
Amino acid<br />
attachment site<br />
3′ 5′<br />
Anticodon<br />
(c) Symbol used<br />
in this book<br />
Two dimensional structure. The four base<br />
paired regions <strong>and</strong> three loops are<br />
characteristic <strong>of</strong> all tRNAs as is the base<br />
sequence <strong>of</strong> the amino acid attachment<br />
site at the 3’ end. The anticodon triplet is<br />
unique to each tRNA type as are some<br />
sequences in the other two loops. (the<br />
asterisks mark bases that have been<br />
chemically modified a characteristic <strong>of</strong><br />
tRNA)<br />
The structure <strong>of</strong> transfer RNA (tRNA).<br />
Anticodons are conventionally written 3’∏<br />
5’ to align properly with codons written 5’<br />
∏3’. For base pairing RNA str<strong>and</strong>s must<br />
be antiparallel like DNA. For example<br />
anticodon 3’ AAG 5’ pairs with mRNA<br />
codon 5’ UUC 3’<br />
Accurate translation requires two steps:<br />
First: a correct match between a tRNA <strong>and</strong> an amino<br />
acid, done by the enzyme aminoacyl-tRNA synthetase<br />
Second: a correct match between the tRNA anticodon<br />
<strong>and</strong> an mRNA codon<br />
Flexible pairing at the third base <strong>of</strong> a codon is called<br />
wobble <strong>and</strong> allows some tRNAs to bind to more than one<br />
codon
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