That would be the ribosomes, but they are also floating free in the cytosol forming their part in the cytoplasmic material.
mitochondria
The rough endoplasmic reticulum is a network of membranes involved in the production of proteins. Protein synthesis occurs in the ribosomes, which are attached to the outside of the rough ER, giving it a 'rough' appearance.
Endoplasmic reticulum
its a rough endoplasmic reticulum.
Ribosomes
Endoplasmic reticulum synthesizes (or helps in processing) proteins and lipids for the cell's organelles. In rough ER the proteins are transferred to the Golgi apparatus to be transported outside of the cell.
The Rough ER produces secretory proteins. Their pathway starts in the Rough ER, then the Golgi Apparatus and they are then packaged and transported outside the cell. Secretory proteins are made on bound ribosomes(ribosomes that don't float freely in the cytoplasm)... hope that helped
The ribosomes attached to the outside of the ER.
in the ribosomes, where mRNA is being translated.
mitochondria
Its the tRNA molecule which assembles amino acids together inside of the ribosome. So technically, you could say that it is the ribosome which assembles them. This is done through a process called 'protein synthesis', more specifically at the translation level.
Ribosomes are small "bumps" located on the rough endoplasmic reticulum.