1. Cytoskeleton, Centrioles, and Flagella Megan, Tristan, Carissa and Nick Troup

2. Centrioles www.basic.northwestern.edu/g-buehler/centrpr.jpg sun.menloschool.org/.../centriole/centriole2.jpg Centrioles: small protein bodies which are found in the cytoplasm of animal cells. http://www.cellsalive.com/mitosis.htm

3. External Structure Formed by groups of microtubules.

4. What cells have them? Located in animal cells…

5. Where it is located? Centrioles are located on the poles of a cell. Initially there is only one pair, but they duplicate before the cell divides.

6. What functions / relations does it have to other organelles? The centrioles form spindle fibres to separate chromosomes during cell division. These spindle fibres are specialized microtubules which are guided by a pair of centrioles which have moved to the pole of the cell. The centrioles simply act as a point where the spindle fibres radiate. When cells divide, the cells pair of centrioles divide and go to opposite sides of the cell.

7. Possible Malfunctions The centrioles could incorrectly hold the spindle fibres, which would in turn in properly hold the chromosomes.

8. Cytoskeleton ; a network of three different types of protein filaments called microtubules, intermediate filaments, and microfilaments that branch throughout the cytoplasm and serve a variety of mechanical and transport functions.

9. External Functions The cytoskeleton encompasses the cell membrane, and allows the cell as a whole to have more stability. The cytoskeleton is also responsible for overall cell mobility.

10. Interior Functions The cytoskeleton has three main components that hold it together. These are microtubules, microfilaments, and intermediate filaments. Microtubules are hollow tubes that act as a framework that motor proteins can attach to so that the entire cell can be transported. Microfilaments are thin strands that form in bundles or networks. They help parts of the cell move, and they determine and stabilize the cell’s shape. Intermediate filaments are wide in variety, and help resist tension in the cell.

11. What cells have them? Cytoskeletons are generally found in eukaryotic cells. They are more common in animal cells because there is no cell wall present.

12. Where it is located? The cytoskeleton is located on the outmost part of the cell membrane, and encompasses the entire cell, including the cell membrane.

13. What functions / relations does it have to other organelles? The cytoskeleton helps maintain the overall shape of the cell so that all the internal organelles can function properly. The cytoskeleton also allows whole cell mobility.

14. Flagella

15. External Functions In larger animals, the flagella are often arranged in large numbers at the surface of a stationary cell anchored with an organ and serve to move fluids along mucous membranes, such as the lining of the trachea.

16. Interior Functions There are three different types of flagellum: Bacterial, Archaeal, and Eukaryotic. Bacterial flagella are helical filaments that rotate like screws. Archaeal flagella are similar to bacterial flagella, but are different because they are considered non-homologous, and require energy to function. (non-homologous – being unlike genetic constitution) Eukaryotic flagella are those of animal, plant and protest cells that are complex cellular projections that lash back and forth.

17. What cells have them? Mostly animals and some plants.

18. Where it is located? A flagellum (plural: flagella) is a long, slender projection from the cell body.

19. Structure The outside of the flagellum are generally the same in a long slender projection. Bacterial flagellum is made up of the protein flagellin ( flagellin – a protein that arranges itself in a hollow cylinder). Its shape is a 20nm- thick hollow tube. It is helical and has a sharp bend just outside the outer membrane. The bacterial flagellum is driven by a rotary engine and is made up of protein, located at the flagellums anchor point on the inner cell membrane. It is powered by the movement of protons across the bacterial membrane due to a concentration gradient. Archaeal flagellum is the same as bacterial flagellum only it requires energy from the cell to make it propel. Eukaryotic flagellum is a bundle of nine pairs of microtubule doublets surrounding two central single microtubules. It requires energy from the cell to move itself by beating rapidly back and forth.

20. Possible Malfunctions Smoking causes the flagella to be covered by solid coal particles, which prevents the flagella from preventing the deposit of solid particles present in the air. This slowly causes cells to die and the lung loses its breathing efficiency.

21. Microtubules - Long, hollow, cylindrical type structures that are about 25nm in diameter. They are composed of proteins. Some of their major roles within the cell are as follows: - They form a rigid internal skeleton for some cells. - They act as a framework along which motor proteins can move structures within the cell.

22. Why is a cytoskeleton important to the cell? - It surrounds the cell and maintains its shape. - It provides for various types of cellular movement. - It positions organelles within the cell. - Some of its fibres act as tracks or supports for motor proteins, which move organelles within the cell. - It interacts with extra cellular structures, helping to anchor the cell in place.

23. Microfilaments - exist in single filaments, in bundles or in networks. They are about 7nm in diameter and up to several micrometers in length. Microfilaments have two major roles. - They help the entire cell or parts of the cell to move. - They determine and stabilize the cell shape. - Microtubules are the thickest of the three types; microfilaments (or actin filaments) are the thinnest and intermediate filaments are in between, hence the name intermediate.

24. Intermediate filaments - Filaments that are 8-12 nm in diameter. Intermediate networks, unlike microfilaments or microtubules are often permanent. Even after the cell dies, intermediate filaments persist. The intermediate filaments are especially important for the structure and positions of the cells organelles. For example the nucleus sits within a cage of intermediate filaments. In conclusion the two major functions of intermediate filaments are: - Stabilize the cell structure and help with the positioning of the cells organelles. - Resist tension

25. Sources http://www.cod.edu/people/faculty/fancher/CellStructure. htmhttp://www.cod.edu/people/faculty/fancher/CellStructure. htm http://www.cellsalive.com/mitosis.htm http://www.cellsalive.com/cells/cellpix/cell_model.jpg http://www.dkimages.com/discover/previews/810/450306 11.JPGhttp://www.dkimages.com/discover/previews/810/450306 11.JPG http://www.helium.com/tm/93125/smoking-maybe-worst- affectinghttp://www.helium.com/tm/93125/smoking-maybe-worst- affecting http://en.wikipedia.org/wiki/Flagellum Bio 11 Text http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C /Cilia.htmlhttp://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C /Cilia.html