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The Cytoskeleton - Its Functions and Structure

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Introduction

The Cytoskeleton-Its Functions and Structure I have decided to base my essay on the cytoskeleton as this is a very interesting field of biology and there are copious amounts of information and research involving it. I hope by doing this essay I can extend my knowledge of the cytoskeleton and that it may help me during my forthcoming exams. The first thing that must be understood about the cytoskeleton is that it is not present in all living cells. The cytoskeleton is unique to eukaryotic cells and is not present in prokaryotes such as bacteria. It is suggested that the cytoskeleton may have been a crucial factor in the evolution of eukaryotic cells. The cytoskeleton is like a scaffold, made up of fibrous proteins in the cytoplasm of a cell. It's a very dynamic three-dimensional. Cells can easily adopt a variety of shapes and carry out coordinated and directed movements because they possess this network of fibrous proteins. Some of the functions that the cytoskeleton serves that will be discussed more further on in the essay include: establishing cell shape, providing mechanical strength, locomotion, chromosome separation in mitosis/meiosis and intracellular transport of organelles. These diverse activities of the cytoskeleton depend on different types of protein fibres which are, actin filaments (or otherwise known as microfilaments), microtubules and intermediate filaments. It was interesting to discover in the research of my essay that in the book 'Molecular Biology of the Cell' (alberts et al) ...read more.

Middle

They also anchor the centrosomes at opposite poles of the cell during mitosis. Actin filaments are the critical components of the submembrane cytoskeleton in red blood cells. They are also involved with the movement of cells and cellular processes. These movements occur both during development and in adults. For example they are involved in formation of the mesoderm and in the healing of wounds. These movements can also occur abnormally and are closely related to cancer. Actin filaments are also thought to play a part in the uptake and discharge of material from the cell via membrane-bound vesicles i.e. endocytosis and exocytosis. Another one of their several functions is to interact with myosin filaments (also known as thick filaments) in skeletal muscle fibres to provide the force of muscular contraction. Intermediate filaments are rope-like fibres with a diameter of around 10nm. They are a family of related structures, all the same size, performing similar functions, and composed of related proteins, but with different forms found in different cell types. They are made of intermediate filament proteins, a group of molecularly and morphologically similar proteins with wide biochemical diversity. All intermediate filament proteins are elongated proteins that form coiled coils and assemble side-by-side. Intermediate filaments are more stable and long-lived than actin filaments or microtubules. For example, keratin filaments (a class of intermediate filament) can remain intact even after the cell that contains them disintegrates. In most animal cells an extensive network of intermediate filaments surrounds the nucleus and extends out to the cell periphery, where they interact with the plasma membrane. ...read more.

Conclusion

Cilia and flagella are constructed from microtubules and both provide either locomotion for the cells (e.g. sperm) or move fluid past cells (e.g. ciliated epithelial cells that line the oesophagus and move a film of mucus towards the throat. Cilia and flagella both have the same basic structure. If a cell has many short ones, they are known as cilia and if the cell has few long ones they are known as flagella. Each cilium (or flagellum) is made of a cylindrical array of 9 evenly spaced microtubules, each with a partial microtubule attached. The entire assembly is sheathed by a membrane that is simply an extension of the plasma membrane. The motion of cilia and flagella is created by microtubules sliding past one another. This requires motor molecules of dynein, which link adjacent microtubules together, and the energy of ATP. The fourth type of protein fibre that makes up the cytoskeleton, which there wasn't a significant amount of information about is the microtrabeculae. These are tiny fibres and they have a very important function, they interconnect all of the structures within the cell. It is believed that, like intermediate fibres, the microtrabeculae help to give the cell shape. The cytoskeleton really is a fascinating structure of which there still many things not yet understood. I predict that sometime in the near future, new discoveries concerning the cytoskeleton may play a part in finding a cure for cancer because already there are many links between the cytoskeleton and cancerous cells. I hope in this essay I have given a clear account of what the cytoskeleton is and the many components it is made up of. ...read more.

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