Proteins are synthesized in a cell's ________________?

ribosomes. if you want to specifically know where the site of protein synthesis is, it would be the ribosomes. The nucleus provides the template for protein production via production of mRNA and transport them out into cytoplasm via tRNA. the ribosome itself is made up of protein and rRNA. but since this question is dealing with production of protein, i would say it's in the ribosomes.