Ribosomes 

Ribosomes are the sites where protein molecules are synthesized from amino acids. They are composed of proteins and RNA. Some ribosomes are found bound to the granular endoplasmic reticulum, while others are free in the cytoplasm. The proteins synthesized on ribosomes bound to granular endoplasmic reticulum are transferred from the lumen (open space inside endoplasmic reticulum) to the Golgi apparatus for secretion outside the cell or distribution to other organelles. The proteins that are synthesized of free ribosomes are released into the cytosol.