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Cystic Fibrosis

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Introduction

Cystic Fibrosis Cystic Fibrosis (CF) is an inherited disease caused by a mutation in a gene responsible for producing a protein called "cystic fibrosis transmembrane regulator" (CFTR). Most people have 2 genes which produce this protein, but only one is needed to prevent the disease. This means that CF is "autosomal recessive", meaning that a person with the disease has a mutation in both CFTR (one mutated gene from each parent). Someone with one mutated gene and one normal gene is a carrier. Carriers do not show the symptoms of CF, as they have one working gene, but they may pass a copy of the defective gene onto their children. ...read more.

Middle

In the diagram above, there is too little water in the mucus. The CFTR channel opens and allows chloride ions to diffuse out of the cell into the mucus. The sodium channel is closed so the sodium ions cannot enter the cell. Together, this increases the concentration of solutes in the mucus, causing water to travel by osmosis out of the cell and into the mucus. The diagram below shows a cell in a cystic fibrosis sufferer. There is no chloride channel, so the direction of osmosis cannot be changed, so water is constantly leaving the mucus. This leaves the mucus sticky and viscous. In healthy people, mucus in the trachea, bronchi and bronchioles traps any microorganisms or dust to help prevent infection. ...read more.

Conclusion

Mucus can also affect the digestive system by blocking the pancreatic duct, preventing digestive enzymes being released into the intestines. This causes food to not be fully digested, so not all of the nutrients can be absorbed. The trapped enzymes can also damage the pancreas, which can lead to diabetes. Male CF sufferers can be infertile due to an absence of or malfunctioning vas deferens, meaning sperm leaving the testes is blocked or reduced. In females, the cervix can become blocked by a mucus plug, which prevents sperm reaching the egg. Cystic Fibrosis is one of the most common hereditary disorders, with approximately 1 in 25 Europeans carrying the faulty gene. The life expectancy for a sufferer has increased from 5 to 31 years of age in the last 43 years, and scientists are continually getting closer to finding a cure through gene therapy and drugs. ...read more.

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Here's what a star student thought of this essay

4 star(s)

Response to the question

Good overall essay on cystic fibrosis. Sources used could be set out better with the references being put on a separate page with citations and proper referencing throughout the text to receive a higher level. Good depth of analysis and ...

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Response to the question

Good overall essay on cystic fibrosis. Sources used could be set out better with the references being put on a separate page with citations and proper referencing throughout the text to receive a higher level. Good depth of analysis and response to the overall topic, but the topic could have been examined a lot further with possible treatments as well as symptoms.

Level of analysis

Good introduction explaining what cystic fibrosis is. Goes on to explore the content with in depth gene analysis which is what I would expect from a well rounded higher level A level candidate, with multiple diagrams included and explained. Goes on to explain possible future improvements in the work on finding a cure, but could explore around the subject to a much higher level of depth. Could also develop their own conclusions as to how the disease may be treated or evaluate treatments that are available for the condition now rather than only describing symptoms. Does not explore the reasons for infertility in the males which could be another possible route to explore to increase the depth of analysis showed by the candidate. Terms are as expected for this level scientifically.

Quality of writing

One or two extra spaces between words, probably due to typing error and then lack of proofreading the work. Spelling and punctuation are accurate, and the grammar is mainly accurate.


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Reviewed by skatealexia 27/03/2012

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