A question about tRNA

Lluis Ribas lluis at aars.mit.edu
Mon May 12 02:30:22 EST 1997


Klaassen (klaassen at oix.com) wrote:
: 
: 	I was hoping that someone could help me with a question I have :)
: 
: 	I was looking in my Biology text book, and I'm a bit confused about tRNA. 
: I realize that the anticodon attaches to the codon of the mRNA (through the
: ribosome)... but I'm not able to understand is the codon of the tRNA.. is
: it the same as the codon on the mRNA, which would be the compliment to the
: anticodon on the tRNA. More than half of the pictures I have seen of the
: codon have four nucleotides, and none of them match up with the anticodon. 
: Infact, none of the tRNA codons that I have seen match up with the
: anticodons of the same tRNA.
: 
: 	Another question I have is also about the codon on the tRNA.  Wich way is
: it read.  Different books are telling me different things.  Is it read from
: the 3` end like DNA, or is it read backwards?  Depending on the way that it
: is read changes the amino acids that they code for
: 
: 	It's all just that little bit to far over my head... I would apreciate any
: help I could get!!!!




     tRNAs have no codons. They recognize an mRNA  codon through their complementary
  anticodons and carry the amino acid that corresponds to that triplet at the other
  end of their structure. THey are not read like mRNA's, but recognized through  their
  three-dimensional structure by aminoacyl-tRNA synthetases. Those enzymes are 
  responsible for the specific attachment of the amino acids to their correct tRNA's.
  The transfer of that amino acid to the polypeptide chain takes place in the ribosome,
  after the pairing of the mRNA codon with the tRNA anticodon.


      Lluis
: 



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