DNA Translatio1 - peptide chain shifts over to the A site with the original amino acid on the A site as the lowest link in the chain The tRNA in

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DNA Translation Elongation With the formation of the complex containing fMet-tRNA in the peptidyl site, an aminoacyl tRNA with the complementary anticodon sequence can bind to the mRNA passing through the acceptor site. This binding is aided by elongation factors that are dependent upon the energy from the hydrolysis of GTP. Elongation factors go through a cycle to regenerate GTP after its hydrolysis. Now, with tRNA bearing a chain of amino acids in the p site and tRNA containing a single amino acid in the A site, the addition of a link to the chain can be made. This addition occurs through the formation of a peptide bond, the nitrogen-carbon bond that forms between amino acid subunits to form a polypeptide chain. This bond is catalyzed by the enzyme peptidyl transferase. Figure %: Peptide Formation
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The peptide bond occurs between the carboxyl group on the lowest link in the peptide chain located at the p site and the amine group on the amino acid in the A group. As a result, the
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Unformatted text preview: peptide chain shifts over to the A site, with the original amino acid on the A site as the lowest link in the chain. The tRNA in the A site becomes peptidyl RNA, and shifts over to the P site. Meanwhile, the ribosome engages in a process called translocation: spurred by elongation factors, the ribosome moves three nucleotides in the 3' prime direction along the mRNA. In other words, the ribosome moves so that a new mRNA codon is accessible in the A site. Figure %: Translocation With the A site open again, the next appropriate aminoacyl tRNA can bind there and the same reaction takes place, yielding a three-amino acid peptide chain. This process repeats, creating a polypeptide chain in the P site of the ribosome. A single ribosome can translate 60 nucleotides per second. This speed can be vastly augmented when ribosomes link up to form polyribosomes....
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This note was uploaded on 01/27/2012 for the course BIOLOGY BSC1005 taught by Professor Rodriguez during the Winter '09 term at Broward College.

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DNA Translatio1 - peptide chain shifts over to the A site with the original amino acid on the A site as the lowest link in the chain The tRNA in

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