Ribosomes, Endoplasmic Reticulum, & Golgi Apparatus

Ribosomes are small protein structures containing ribosomal RNA. They synthesize proteins for the cell that are in the cytoskeleton or are incorporated into the cell membrane or exported from the cell. Free ribosomes float in the cytosol while membrane-bound ribosomes are attached to the endoplasmic reticulum.

The endoplasmic reticulum is a system of tubes and membranes surrounding the cisternae. The ER is adjacent to the nucleus of a cell. The rough ER has ribosomes attached to it that synthesize proteins. It produces membranes for the cells and has lipid-catalyzing enzymes on it. The smooth endoplasmic reticulum is a continuation of the rough ER without the ribosomes. It's enzymes catalyze reactions like hormone synthesis, fat absorption synthesis and transport, drug and pesticide detoxification, glycogen breakdown, and lipid metabolism.

The Golgi apparatus is flat, stacked membranous sacs and vesicles that take proteins and lipids produced in the ER and modifies, concentrates, and transports the molecules. The proteins and lipids are packaged into vesicles then either expelled from the cell by exocytosis or brought to the membranous organelle where they are needed. It also packages lysosomes which digest and stay in the cell.

The ribosomes, endoplasmic reticulum, and Golgi apparatus all work together in the process of making substances necessary for the cell and distributing them where they need to go.