Final answer:
Pyruvate kinase mRNA is translated by free ribosomes, as it is used for glycolysis in the cytoplasm and not destined for secretion or organelles other than the cytosol.
Step-by-step explanation:
Pyruvate kinase is an enzyme used for glycolysis in the cytoplasm of all cells. The mRNA coding for pyruvate kinase would be translated by free ribosomes in cells. This is because pyruvate kinase functions in the cytosol, and proteins destined for the cytoplasm are typically synthesized by free ribosomes. In contrast, bound ribosomes, which are attached to the endoplasmic reticulum, synthesize proteins primarily for secretion or for use in lysosomes or the endoplasmic reticulum itself.