Introduction | Structures/Functions | Prokaryotes vs. Eukaryotes | Types | Reproduction | Theory | Glossary | Credits

Within cells there is an intricate network of organelles that all have unique functions. These organelles allow the cell to function properly. Arranged below according to location (nucleus, cytoplasm, and surface) is a description of common organelles. You may click on the organelle's name in the list below to directly reach the feature on that structure.

Cell wall Centrioles Chloroplasts Chromosomes Cytoskeleton Endoplasmic reticulum Nuclear membrane

Nucleolus Golgi apparatus Lysosome Mitochondria Plasma membrane Ribosomes Vacuoles

	One or more per cell Spherical shape Denser than surrounding cytoplasm
		Chromosomes - Usually in the form of chromatin - Contains genetic information - Composed of DNA - Thicken for cellular division - Set number per species (i.e. 23 pairs for human)
		Nuclear membrane - Surrounds nucleus - Composed of two layers - Numerous openings for nuclear traffic
		Nucleolus - Spherical shape - Visible when cell is not dividing - Contains RNA for protein manufacture

	Collective term for cytosol and organelles contained within Colloidal suspension Cytosol mainly composed of water with free-floating molecules Viscosity constantly changes
		Centrioles - Paired cylindrical organelles near nucleus - Composed of nine tubes, each with three tubules - Involved in cellular division - Lie at right angles to each other
		Chloroplasts - A plastid usually found in plant cells - Contain green chlorophyll where photosynthesis takes place
		Cytoskeleton - Composed of microtubules - Supports cell and provides shape - Aids movement of materials in and out of cells
		Endoplasmic reticulum - Tubular network fused to nuclear membrane - Goes through cytoplasm onto cell membrane - Stores, separates, and serves as cell's transport system - Smooth type: lacks ribosomes - Rough type (pictured): ribosomes embedded in surface
		Golgi apparatus - Protein 'packaging plant' - A membrane structure found near nucleus - Composed of numerous layers forming a sac
		Lysosome - Digestive 'plant' for proteins, lipids, and carbohydrates - Transports undigested material to cell membrane for removal - Vary in shape depending on process being carried out - Cell breaks down if lysosome explodes
		Mitochondria - Second largest organelle with unique genetic structure - Double-layered outer membrane with inner folds called cristae - Energy-producing chemical reactions take place on cristae - Controls level of water and other materials in cell - Recycles and decomposes proteins, fats, and carbohydrates, and forms urea
		Ribosomes - Each cell contains thousands - Miniature 'protein factories' - Composes 25% of cell's mass - Stationary type: embedded in rough endoplasmic reticulum - Mobile type: injects proteins directly into cytoplasm
		Vacuoles - Membrane-bound sacs for storage, digestion, and waste removal - Contains water solution - Contractile vacuoles for water removal (in unicellular organisms)

		Cell wall - Most commonly found in plant cells - Controls turgity - Extracellular structure surrounding plasma membrane - Primary cell wall: extremely elastic - Secondary cell wall: forms around primary cell wall after growth is complete
		Plasma membrane - Outer membrane of cell that controls cellular traffic - Contains proteins (left, gray) that span through the membrane and allow passage of materials - Proteins are surrounded by a phospholipid bi-layer.

Organelle Links Cells and Organelles http://www.life.uiuc.edu/bio100/lessons/cells_and_organelles.html The Insides of Cells http://kauai.cudenver.edu:3010/0/nutrition.dir/organelle.html Structures and Function of Organelles http://esg-www.mit.edu:8001/esgbio/cb/organelles.html Why Are There Organelles? http://iip.ucsd.edu/Step/projects95/cellular.Organelles/WHY.HTM Cellular Organelles http://iip.ucsd.edu/Step/projects95/cellular.Organelles/CELLS.HTM Microfilaments and Microtubules--The Cytoskeleton http://www-class.unl.edu/bios201/group6/cytoskel.html Eukaryotic Cell Membrane or Plasma Membrane http://www.bio.mtu.edu/campbell/eukaryot.htm The Nucleus, Nucleolus, Nuclear Envelope, and everything you ever wanted to know about DNA (but were afraid to ask) http://www-class.unl.edu/bios201/group6/nucleus.html Lysosomes http://www-class.unl.edu/bios201/group6/lyso.html The Rough and Smooth Endoplasmic Reticulum http://www-class.unl.edu/bios201/group6/er.html The Endoplasmic Reticulum http://lenti.med.umn.edu/~mwd/back/cell_www/chapter2/ER.html The Golgi Bodies http://www-class.unl.edu/bios201/group6/golgi.html Centrioles http://www-class.unl.edu/bios201/group6/centrio.html Mitochondria http://www-class.unl.edu/bios201/group6/mitochon.html