Page 62 - The Miracle in the Cell

THE MIRACLE IN THE CELL
Carefully, the assembly system begins to manufacture the plane.
Its every part is brought by an assembly robot responsible solely for
that particular piece and then is assembled in the correct location. The
smallest error will later result in the plane falling out of the sky; but
the system makes no mistake. On the rare occasion a defective prod-
uct is produced, it passes through sensitive quality-control check-
points and is removed from the assembly line, whereupon the
defective product is disassembled and its parts are used for new prod-
ucts. Nothing is wasted. At the same time, the factory is able to pro-
duce hundreds of other products such as dialysis machines,
computers, and cars. Some of these products it uses for itself, and oth-
ers it exports outside.
The cell's organization is actually much more perfect than this
science-fiction analogy suggests. As mentioned before, the human
body uses more than 200,000 different types of proteins, and all of
these are synthesized in the cell. The plans for all of these proteins are
also found in the cell. But the cell selects from its DNA only the infor-
mation needed to make the proteins it will use for itself or it will
export outside, and then makes only these proteins. The functional
differences between the proteins it produces are at least as great as the
differences between those of a plane and a television.

How Is the Synthesis of Proteins Realized?
- Whenever the body needs a protein, a cell or a group of cells
goes into action to implement a series of complex processes. This may
be a type of protein that the cell may need to use in its own structure
or that it will export for outside use. The cell itself decides which pro-
teins it will use within its own structure, but when it comes to making
proteins for outside use, special messenger proteins are sent to the cell.
- All information about the particular protein's structure is
encoded in the nucleus within the DNA. All instructions relevant to
the protein to be made are copied from the DNA with the aid of many

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