Initiationis the second
stage in translation. It is here that the ribosome attaches to the strand of
mRNA, and the first charged tRNA molecule appears. Clicking on each
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To begin initiation, the small subunit of
a ribosome attaches to the mRNA. The area where it first attaches is an
untranslated section of mRNA located near the cap.
The small subunit then moves along the mRNA until it
reaches the first readable codon. This codon always codes for the amino
The tRNA molecules are the next to enter. These charged
molecules of RNA bring the amino acids to the ribosome.
Each tRNA has a triplet coding sequence that corresponds
with the amino acid it carries along.
The triplet sequence of the tRNA is complementary to
the triplet codon sequence in the mRNA.
Each triplet codon sequence in the mRNA and the tRNA
corresponds to a specific amino acid.
After the first tRNA moves into place, the large subunit
of the ribosome attaches to the small subunit.
The complete ribosome consists of two sites: petidyl
(left) and aminoacyl (right).