Organelles

Organelles are separate compartments in eukaryotic cells that contain different enzymes and molecules and have specific roles in maintaining cell structure and function ^[1]. 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.
• Nuclear envelope - surrounds the nucleus, allows passage of material into and out of the nucleus. Eg 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^[2]
• Cytoskeleton - Important role in cell movement and cell division ^[3]
• Plasma membrane - controls what enters and leaves the cell

Prokaryotic Organelles and their Functions:

• Cell Wall - this gives the cell its shape, 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. ^[4]

References

1. ↑ 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
2. ↑ Becker's World of the CellfckLRHardin, J. et al. (2012) Becker's World of the Cell. 8th ed. San Francisco: Pearson, p.253.
3. ↑ Becker's World of the CellfckLRHardin, J. et al. (2012) Becker's World of the Cell. 8th ed. San Francisco: Pearson, p.422.
4. ↑ Available: http://quizlet.com/14315658/function-of-organelles-in-both-prokaryotic-and-eukaryotic-cells-flash-cards/. Last accessed 25/11/14