Page 139 - The Cell in 40 Topics

fter the information in the DNA needed for protein produc-
tion in the cell is located and copied, it must reach the fac-
tory—in other words, the ribosomes—where production is
to be carried out. These organelles, present in every cell, lie quite a distance
from the DNA in the nucleus and are distributed throughout the cell’s cy-
toplasm, the cell’s internal fluid.
Production orders must be forwarded to these factories in perfect
form and at high speed. The messenger RNA (mRNA) finds the ribosome
from among all the many organelles inside the cell without losing its way.
When the mRNA locates the ribosome, it settles onto its exterior in the form
of a line.
The information belonging to the amino acid sequence of the desired
protein has thus reaches the production center. Now, messages begin being
sent to the other regions of the cell for the raw materials—amino acids, in
other words—necessary for the protein to be produced and brought in
(Figure 107). 23
The task of searching for and finding the amino acids to be used and
of bearing them to the ribosome belongs to transporter RNA (tRNA). There

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