Page 64 - The Miracle in the Cell

THE MIRACLE IN THE CELL
enzymes and a strand of RNA molecule produced from this DNA. The
protein will be produced according to the information in this RNA,
which has been copied from the DNA. And so, this RNA is referred to
as messenger RNA (mRNA; Figure 3.1 ).
- The mRNA, having received its instructions, heads towards the

Figure 3.3
In the cytoplasm are found
for protein synthesis pools
of amino acids, tRNAs
(transfer RNAs), and ribo-
somal subunits.

1. First, a tRNA molecule
binds to a small ribosomal
subunit.

2. The subunit binds to the
start codon (AUG) on the
mRNA transcript.

3. A large ribosomal subunit
binds with the small one to
form a production complex.

mRNA
mRNA binding
site
tRNA

PRODUCTION
first tRNA econd tRNA
COMPLEX binding site binding site
(In order to start
production, an 1. Relative posi- 2. Protein synthesis 3. The amino acid corre-
mRNA binds onto tions of the bind- begins with the bringing sponding to the second
an intact ribosome ing sites for of the amino acid by the codon is brought by its
made up of the tRNAs and the tRNA corresponding to tRNA to the ribosome.
two subunits.) mRNA the codon (AUG) that
orders the start of protein
synthesis.
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