FOCUS
Translation
Cytosol
(site
of translation)
Nucleus
(site
of transcription)
Template
strand of
DNA
Newly made (and edited)
mRNA leaves nucleus and
travels to a free or attached
ribosome for decoding.
Pre-mRNA
mRNA
Large
ribosomal
subunit
Small
ribosomal
subunit
A
site
Start
codon
Initiator tRNA
bearing anticodon
Aminoacyl-tRNA
synthetase
Methionine
(amino acid)
The correct amino
acid is attached
to each species
of tRNA by a
synthetase enzyme.
Amino acid
corresponding
to anticodon
tRNA
Figure 3.37
Translation is the process in which genetic information carried by
an mRNA is decoded in the ribosome to form a particular polypeptide. The
“translators” are tRNA molecules that can recognize and bind specifically both
to a codon and an amino acid.
1
Initiation.
Initiation occurs
when four components combine:
• A small ribosomal subunit
• An initiator tRNA that carries
the amino acid methionine
• The mRNA
• A large ribosomal subunit
Once this is accomplished, the
next phase, elongation, begins.
Met
Met
Met
P
site
E
site
A
U
A
U
G
C
A
U
G
C
U
C
U
C
A
U
C
A
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