Final answer:
Ribosomes are the cellular structures responsible for protein synthesis. They translate the genetic instructions from the nucleus into proteins.
Step-by-step explanation:
Ribosomes are the cellular structures responsible for protein synthesis. When viewed through an electron microscope, ribosomes appear either as clusters (polyribosomes) or single, tiny dots that float freely in the cytoplasm. They may be attached to the cytoplasmic side of the plasma membrane or the cytoplasmic side of the endoplasmic reticulum. Ribosomes consist of large and small subunits, and they receive the genetic instructions from the nucleus in the form of messenger RNA (mRNA), which they translate into a specific order of amino acids to build proteins.