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What is DNA?

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  • Essay length: 2578 words
  • Submitted: 18/02/2009
  • Reviewed by: (?) pratstercs
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GCSE Humans as Organisms

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The first 200 words of this essay...

DNA

DNA, otherwise known as deoxyribonucleic acid has changed our lives, including our perception of life, by both scientists and the average person. Science has developed dramatically due to the discovery of DNA.

DNA was first discovered by the Swiss physician Friedrich Miescher and Gregor Mendel who, in 1869, discovered a microscopic substance in the pus of discarded surgical bandages. As it resided in the nuclei of cells, he called it "nuclein". In 1919 this discovery was followed by Phoebus Levene's identification of the base, sugar and phosphate nucleotide unit. Levene suggested that DNA consisted of a string of nucleotide units linked together through the phosphate groups. However, Levene thought the chain was short and the bases repeated in a fixed order. In 1937 William Astbury produced the first X-ray diffraction patterns that showed that DNA had a regular structure.

In 1943, Oswald Theodore Avery discovered that traits of the "smooth" form of the Pneumococcus could be transferred to the "rough" form of the same bacteria by mixing killed "smooth" bacteria with the live "rough" form. Avery, along with coworkers Colin MacLeod and Maclyn McCarty, identified DNA as this transforming principle.DNA's role in heredity was confirmed in

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Review of essay

Reviewed by: pratstercs

Rating: 5 star(s)

Response to the question

Overall, this is a very good piece, with clear understanding of the topic, with lots of facts and explanations showing understanding of what you are talking about. There is a good explanation and history of DNA, with appropriate facts, as well as a good expansion on the topic with information on replication with meiosis and mitosis as well, which helps demonstrate your knowledge of the entire syllabus, but is not out of place on the topic of DNA, as it adds more information over and above what is expected. Images also help accompany the detailed explanation and are well placed within the piece.

Level of analysis

Technical language is used extensively throughout the piece, but is sparse enough to make the piece readable. Pictures and facts are used to support structured points which are developed throughout, as well as explained to demonstrate your understanding. I would either remove or rewrite the final conclusion, as it seems very informal, in contrast to the rest of the piece and seems to lower the tone slightly, which is a shame as this is an intelligent piece, as you have shown you understand the topic, as well as related information in the syllabus, such as meiosis and mitosis.

Quality of writing

My only negative comments on this piece are on the level of English portrayed in the piece. You clearly have shown your intelligence, but the short sentences and lack of flow between some sentences lets you down. If you restructure your sentences a bit more, and rebuild a sentence rather than tacking an extra bit on the end, it will read a lot better and make the piece look far more sophisticated.

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