The organelle crucial for protein synthesis is the ribosome. Ribosomes can be found either free-floating in the cytoplasm or attached to the endoplasmic reticulum. They are composed of ribosomal RNA and proteins and serve as the site where amino acids are assembled into proteins according to the sequence of messenger RNA (mRNA). Understanding ribosomes is essential in molecular biology, as their function is integral to the expression of genes and the maintenance of cellular function.