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Specialised Cells

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Introduction

With the aid of annotated diagrams, discuss the relationship between the structure and function in four specialised human cells. By Mark Cannan. Within the human body the cell is the smallest living organism, it is a microscopic package that contains lots of different organelles that are necessary to survive such as mitochondria, nucleus, Golgi body, rough and smooth endoplasmic reticulum, ribosomes, lysosomes, cytoplasm just to name a few. Cells were first discovered by Robert Hooke, an English philosopher in 1665 and from there, a cell theory was formed. Through the improvement and development of microscopic technologies, cells were looked at even closer and separated into two categories, prokaryotic (bacteria) cells and eukaryotic (animal) cells. There are over two hundred different types (in all shapes and sizes) and it is estimated that there are over 50 trillion cells in the human body. Cells reproduce all the time through mitosis to replace damaged or dead cells. http://en.wikipedia.org/wiki/File:Simplified_spermatozoon_diagram.svg (Accessed 30/10/09) The picture above is an illustrated diagram of a spermatozoon cell, otherwise known as a sperm, which is the male reproductive cell. ...read more.

Middle

Having investigated the sperm cell, we will now look at a motor neuron cell. This is a specialized cell in the nervous system that processes and transmits information around the body by nerve impulses. There are two types of nerve cell in the human body; sensory which control touch, sound, light and motor which receive signals from the brain and spinal cord also causing muscle contractions. The cell body forms the grey matter of the nervous system, it is found at the periphery of the brain and in the centre of the spinal cord (Waugh and Grant, 2006. P143). Within the cell body are all the organelles that would be found in a normal cell including the nucleus, mitochondria, Golgi body and is bound by a cell membrane. In addition to these organelles are the 'tree like branches' called dendrites, these receive and carry the incoming impulses towards the cell body. The long sausage like tail contains the axon which is made up of postganglionic fibres; these carry impulses away from the cell body. ...read more.

Conclusion

Having now looked at three specialised cells, we will investigate our final one. The diagram below shows human erythrocytes otherwise known as red blood cells (RBC). The only organelle red blood cells contain is a plasma membrane; this is so that they have more room for the haemoglobin, the large pigmented protein responsible for gas transport (Waugh and Grant, 2006, p59) which is the main function of RBC. These cells are flexible so that they can squeeze through narrow capillaries. http://img.webmd.com/dtmcms/live/webmd/consumer_assets/site_images/articles/health_tools/fatigue_slideshow/artlife_rf_image_of_red_blood_cells.jpg (accessed 02/11/09). Red blood cells are produced in red bone marrow and go through several stages of development before entering the blood stream. When these cells mature (roughly 1 - 2 days in the blood stream), they lose their nucleus and become incapable of cell division. Their main job is to transport oxygen with some traces of carbon dioxide around the body. In conclusion, there are many cells within the human body with some being specialised cells. They are constantly repairing and producing new cells through the process of mitosis. The four cells mentioned above all have their own specialised functions and a very important part to play in the human body's day to day life. ...read more.

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Response to the question

Okay as a basic structure piece, but does not link structure to function well at all. Introduction is okay, but goes into the background of how cells were discovered too much which is not the main point of the essay, ...

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Response to the question

Okay as a basic structure piece, but does not link structure to function well at all. Introduction is okay, but goes into the background of how cells were discovered too much which is not the main point of the essay, also too descriptive, the text could be a lot more concise and to the point of what the essay is going to be about and the four cell types that the candidate is going to discuss which is not mentioned at all. Main body of the text could link structure to function a lot better than it currently does, and it is below the level I would expect from an A level candidate. Conclusion could have grouped the different cells and their functions and importance together a lot better. References at the end hard to read with the font obscuring most of the words.

Level of analysis

Diagrams are at the level I would expect for A level, but rather than being copied from the internet it would have been better to see them hand drawn and the relevant bits related to the course then labelled, perhaps formulating it as a spider diagram around the picture relating each labelled part to its function and linking parts together to form unified functions. Diagrams overlap the text in spaces which should have been avoided. Links as references are put into the main body of text when they should have been cited properly and then included in a bibliography at the end of the text.Some sentences around the sperm explaining the structure related to function are incomplete. I would also like the simplistic analysis of the function described in more depth. The text after the diagram does not develop the essay further but repeats the text again and adds in some irrelevant facts. Does not link structure to function very well throughout the essay, only limited linkage.

Quality of writing

Some issues with spacing between words and using capital letters where they are not needed. Spelling okay, some issues with grammar in places and the rest of the punctuation mainly okay.


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Reviewed by skatealexia 07/03/2012

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