A connection also connects the endoplasmic reticulum with the plasma membrane. Rough endoplasmic reticula have ribosomes on their surface, whereas, smooth endoplasmic reticula lack ribosomes. The functions of the endoplasmic reticulum are to increase the cell's surface area and to provide a passageway for transport products. Molecules packaged into membrane structures called vacuoles and vesicles. Mitochondria contain a double-membrane boundary in which the inner membrane is folded to form cristae.
Mitochondria are the site of energy production for cells.
Follow links from main page to cell topics. Try some of the tutorials. Download and watch the animations. The Biology Project Also - explore cell size and other activities at the Cells Alive Site. All of these links can also be found under BioLinks.