  Ribosome is a molecular machine that moves on a mRNA track while,
simultaneously, polymerizing a protein using the mRNA also as the corresponding
template. We define, and analytically calculate, two different measures of the
efficiency of this machine. However, we arugue that its performance is
evaluated better in terms of the translational fidelity and the speed with
which it polymerizes a protein. We define both these quantities and calculate
these analytically. Fidelity is a measure of the quality of the products while
the total quantity of products synthesized in a given interval depends on the
speed of polymerization. We show that for synthesizing a large quantity of
proteins, it is not necessary to sacrifice the quality. We also explore the
effects of the quality control mechanism on the strength of mechano-chemical
coupling. We suggest experiments for testing some of the ideas presented here.
