Organelles are separate compartments in eukaryotic cells that contain different enzymes and molecules and have specific roles in maintaining cell structure and function . Each organelle has its own membrane in the form of a lipid bilayer, this allows compartmentalisation and segragation of different chemical activites. Different organelles can be seperated by centrifugation due to their varying densities.
Eukaryotic Organelles and their Functions:
- Ribosomes - host sites for protein synthesis: translation of mRNA into proteins. (80s)
- Nucleus - contains chromosomes as a store of genetic information.
- Nucleolus - a dense structure located in the nucleus, makes ribosomal subunits.
- Nuclear envelope - surrounds the nucleus, allows passage of material into and out of the nucleus. E.g. mRNA
- Rough ER (endoplasmic reticulum) - located next to the nucleus, the rough ER has docked ribosomes for protein synthesis.
- Smooth ER - endoplasmic reticulum without docked ribosomes - synthesis of lipids and steroids
- Lysosome - contain hydrolytic enzymes for intracellular degredation
- Endosomes - sort endocytosed materials.
- Golgi Body - post-transcriptional modification, separation and assortment of newly synthesised proteins
- Peroxisomes - contain enzymes for oxidation of toxins
- Mitochondria - powerhouse of the cell that plays a key role in aerobic cell respiration
- Cytoskeleton - Important role in cell movement and cell division 
- Plasma membrane - controls what enters and leaves the cell
Prokaryotic Organelles and their Functions:
- Cell Wall - this gives the cell its shape and structure, can anchor the appendages (flagella and pili)
- Plasma membrane - controls what enters and leaves the cell (also present in eukaryotic cells)
- Ribosomes - the site of protein synthesis, (70s)
- Nucleoid - this is an area in the cytoplasm where strands of DNA are found, and it is not a membrane bound organelle.
- Pili - these are hair-like projections coming from outside of the cell, this attachs to other cell surfaces.
- Flagella - hairlike structures allowing the cell to move by beating in a corkscrew-like motion to nutrients and chemicals. 
- Mesosomes - These are folded invaginations of the plasma membrane. They can contain various enzymes used in respiration.
- ↑ Alberts B, Johnson A, Lewis J, Raff M, Roberts K, Walter P. 2008. Molecular Biology of the Cell. 5th Edition. p695. Garland Science, New York
- ↑ Becker's World of the CellfckLRHardin, J. et al. (2012) Becker's World of the Cell. 8th ed. San Francisco: Pearson, p.253.
- ↑ Becker's World of the CellfckLRHardin, J. et al. (2012) Becker's World of the Cell. 8th ed. San Francisco: Pearson, p.422.
- ↑ Available: http://quizlet.com/14315658/function-of-organelles-in-both-prokaryotic-and-eukaryotic-cells-flash-cards/. Last accessed 25/11/14
- ↑ http://www.ivyroses.com/Biology/Cells/Prokaryotic-Cell-Structure.php