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Specialised cells.

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SPECIALISED CELLS "A human body contains about 50 million million cells" (Boyle, Ingham, Senior, 1999,pg 2). A cell is the smallest unit of any organism. Inside each cell are different types of specialised components called organelle, each with their own features and specific function. (See diagram below). Each task completed is needed by the cell in order to survive. ==> The nucleus is the control centre of the cell, controlling the goings on inside the cell. Inside the nucleus there is a nucleolus. This nucleolus contains the cells DNA and is responsible for synthesising ribosomes. ==> The Endoplasmic Reticulum creates a path so that molecules can move from one part of the cell to another. Rough ER is lined with ribosomes and Smooth ER has no ribosomes attached and is the site of steroid production. ==> Ribosomes are the site of protein synthesis in a cell. Some are free in the cytoplasm; others line the membranes of the Rough ER. ...read more.


Looking at diagram 2 of a RBC we can see that the red blood cell has very few organelle including no nucleus. With all these missing organelle there's more space for more haemoglobin, the substance carries oxygen. With more haemoglobin the cell can carry more oxygen at once and be more efficient at its job. Its biconcave disc shape that gives it a greater surface area, which means there is more space to carry more oxygen. They also have flexible membranes so they can bend easily to pass through the tiniest blood vessels without breaking. (Roberts, 1986) Another specialised cell is a white blood cell. A white blood cells function is to fight infection and destroy foreign bodies. To do this job the cell has a flexible membrane, which gives it an irregular shape. This flexi membrane enables the cell to surround the bacteria before it releases its many lysosomes to digest the toxins. ...read more.


(Vander, Sherman, Luciano, l994) Probably the most complex specialised cell is a motor neurone. Diagram 5 shows the structure of a motor neurone .The function of a motor neurone is to transmit nervous impulses to different parts of the body. Like a standard cell there is a cell body (soma), which is like the factory of the neurone, it contains the same organelle as a generalised cell and performs in the same way. However attached to this cell body is lots of little dendrites. These dendrites act as 'antennae' to receive signals from other connected nerves cells. The axon is the conduction part of the neurone. It's a long fibre that transmits the impulse from the cell body as electrical signals that may split to several branches to transmit messages to different organs or muscles. Around the axon is myelin sheath that protects the axon and stops interference with other axons. At junctions with other nerve cells and the target are end plates. These are the sites where the synapses are formed. (http://www.epub.ord.br) and (http://www.web.ukonline.co.uk) Question 1 Rob Hunt Page 1/ 3 ...read more.

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