Compare and contrast a motor nuerone and a bacterium

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The aim of this essay is to compare and contrast a salmonella bacteria (prokaryotic) cell with a motor neurone (eukariotic) cell.

Cells are the basic structures contained in all living organisms, their function, size and shape differ depending on which organism serves as its host. They are catagorised as either eukaryotic or prokaryotic cells, prokaryotic being the old Greek term meaning ‘before nucleus’.

It wasn’t until the 17th century that cells were discovered by the European Antonie van Leeuwenhoek with his latest invention - a very primitive microscope. These new discoveries were later named by an English scientist by the name of Robert Hooke. (Wikipedia 2007)

The eukaryotic cell can be found in either animals or plants, although the two are very different in both structure and function.  The animal cell has a complex internal structure containing many membrane bound organelles that individually have a defined role to play within the cell - more detail will be given about the motor neurone later in this essay. Most animal cells have the same basic parts, namely, nucleus, cell membrane, and cytoplasm with various membrane bound organelles (see appendix 1).

The prokaryotic (bacteria) cell has a more basic structure (see appendix 1) and is much smaller in size, to give an idea of size in microscopic distance, the eukaryote measures between 10-100 micrometres, and the prokaryote can be between 0.1-10 micrometres. The prokaryotes are the oldest cells on earth and have been around for over 3.5 billion years.  Their habitats are hugely varied - they can be found in the air, sea, soil and inside living things.  There are many different forms of the bacterium, however, they share three basic structures - rods known as bacillus, spheres known as coccus and spirals known as spirillium (Appendix 3).  This essay will look at the salmonella bacteria cell which is a bacillus.  (Boyle & Senior 2002)

 

Motor neurones are cells that make up part of the body’s nervous system and are found in either the spinal cord or the brain.  The salmonella cell is usually found on food and ingested, causing gastrointestinal intoxication (vomiting and diarrhoea).

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Unlike most human cells (which are rounded as in appendix 1) the motor neurones are not (see appendix 2), they have a very specific structure.  They resemble wires, and it is these wire-like structures whose function it is to carry the signals (nerve impulses) from the central nervous system to effector organs - for example, the muscles and glands within the body that respond to stimulus.

These cells are stretched out into long thin fibres that can be over a metre in length (unlike the bacteria cell which are amongst the smallest living organisms), and the nerve impulses travel along ...

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