What are the structures called that float within the cytosol and make proteins used within the cell?

The structures that float freely within the cytosol and are responsible for synthesizing proteins used within the cell are known as free ribosomes. These ribosomes are not bound to any membrane and are found dispersed throughout the cytosol, allowing them to translate mRNA into proteins that function in various metabolic processes within the cytoplasm itself.

Free ribosomes produce proteins that typically remain within the cell, such as enzymes or structural proteins, contributing to cellular functions. In contrast, fixed ribosomes, which are attached to the endoplasmic reticulum, are involved in synthesizing proteins that are destined for secretion, incorporation into the cell membrane, or for use in lysosomes. This distinction in ribosomal function is crucial for understanding how cells organize protein synthesis based on the destination and function of the proteins produced.

The Golgi apparatus is primarily involved in modifying, sorting, and packaging proteins for secretion or delivery to organelles, while lysosomes contain digestive enzymes for breaking down waste materials and cellular debris. Therefore, these structures do not play a direct role in synthesizing proteins within the cytosol.