A ribosome<span> is a cell organelle. ... </span>Ribosomes<span> are found 'free' in the </span>cytoplasm<span> or bound to the endoplasmic reticulum (ER) to form rough ER. In a mammalian cell there can be as many as 10 million </span>ribosomes<span>. Several </span>ribosomes<span> can be attached to the same mRNA strand, this structure is called a polysome. </span>Ribosomal<span> protein synthesis in eukaryotes is a major metabolic activity. It </span>occurs<span>, like most protein synthesis, in the </span>cytoplasm<span> just outside the nucleus. Individual </span>ribosomal <span>proteins are synthesized and imported into the nucleus through nuclear pores.</span>
