Organelle Number & Ditribution

=Organelle Number & Distribution= Different tissues (e.g. muscle, bone, skin, etc.) perform different function and therefore the cell types that make up these tissues may need a different number / distribution of organelles. ==Examples== [image:http://i.imgur.com/kemPGgL.gif?3] '''Plant Cells''' Plants cells have large numbers of chloroplasts (green) in order to carry out photosynthesis. Chloroplasts are usually found near the cell surface to reduce diffusion distance. This ensures raid diffusion of carbon dioxide into the chloroplast and oxygen out. You may notice that chloroplasts circulate around the cell periphery. This phenomenon is known as cytoplasmic streaming. Plant cells are quite large and this helps to stir the cytoplasm and distribute substances that would normally take longer to diffuse throughout the cell. [image:http://i.imgur.com/UiR0Chj.png] '''Muscle Cells''' Muscle cells have large numbers of mitochondria (shown in brown) found adjacent to the myofibrils (shown in pink) -protein fibres that generate muscle contractions. Muscle cells require large amounts of energy (ATP) to sustain movement and therefore need large numbers of mitochondria to carry out aerobic respiration and produce cellular energy (ATP). Muscle tissues also have an extensive network of blood vessels that supply them oxygen & glucose and remove carbon dioxide. [image:http://i.imgur.com/HVd9uvw.png?3] '''Goblet Cells''' Goblet cells are found within the lining of the airways and intestines. Goblet cells secrete mucus, which helps to lubricate surfaces and prevent infection. Goblet cells have large numbers of secretory vesicles that transport mucus to the cell surface (exocytosis). The also have an extensive '''''endoplasmic reticulum'''' and large '''''golgi bodies''''' needed to synthesise and the proteins found in mucus (e.g. mucin). Goblet cells have fewer mitochondria that are found closer to those organelles involved in the the production of mucus proteins (the nucleus, endoplasmic reticulum and golgi body). The nucleus is aways found at the base of the cell as it is not involved in the transport of mucus, whereas the vesicles are fount at the cell apex near the intestine / airway surface.