Author Archives: clairetbarnett

Ascorbic Acid, Claire Barnett

Ascorbic Acid, and Its Chemistry    

            Ascorbic acid is also known as Vitamin C. It was the third vitamin ever identified, hence the label “C”. Many mammals make Vitamin C in the liver, by a series of reactions. Out of all mammals, only primates, guinea pigs, and Indian fruit bats must consume the Vitamin C they need.

            In 1928, a Hungarian biochemist named Albert Szent-Györgyi became the first person to isolate a sample of pure Vitamin C. He removed it from the fatty part of the endocrine glands near a cow’s kidney. He did not initially recognize it as Vitamin C, and therefore he resolved to name the substance hexuronic acid. The hex prefix was because of the six Carbon atoms present in the molecule: its chemical formula was C6H8O6. Hexuronic acid was finally recognized as Vitamin C four years later. Szent-Györgyi’s next task was determine the structure of Vitamin C, so he used Hungarian paprika (high in ascorbic acid) to separate over a kilogram of pure Vitamin C crystals. Haworth, a professor of chemistry, successfully helped Szent-Györgyi find ascorbic acid’s structure. Both men received Nobel Prizes for their groundbreaking work.

            Its been more than seventy years, but scientists still don’t know everything about ascorbic acid and its interaction with our bodies. One important protein we have found that Vitamin C helps produce is collagen. Collagen is the most prevalent protein and one of the most important proteins in the animal kingdom. A lack of collagen can cause many of the initial symptoms of scurvy. Ascorbic acid has left its mark on history by being a cure for scurvy.

 

Ascorbic Acid’s Impact on History

             As a crucial human Vitamin, ascorbic acid has many positive effects and much potential. However, its biggest contribution to history has been as a cure for scurvy. It is a disease, caused by Vitamin C deficiency, which has been around since ancient times. Most often scurvy has appeared in sailors who take relatively long voyages without any Vitamin C-rich foods. These long journeys became more frequent and longer near the end of the fifteenth century and through the Age of Discovery, and as a result scurvy became a bigger issue. When sailors were going to be at sea for months, they packed foods that could be easily stored and preserved. There were no refrigerators on the ships, so often the crew would only bring things like bread, cheese, butter, vinegar, dried peas, beer, and rum. These items would eventually go bad, but not as quickly as the fruits and vegetables that happen to have Vitamin C. After as little as six weeks at sea, sailors would begin to show signs of scurvy. On De Gama’s trip around the southern tip of Africa in 1497, about 100 of his 160 crew members perished from scurvy. It was 1601 before English ships, a small fleet under the direction of Captain James Lancaster, would first stop mid-journey and collect oranges and lemons to prevent scurvy. Of the four ships in this group, only the one being run by Lancaster was free of scurvy.

            The benefits of ascorbic acid for scurvy victims was not clinically proven until 1747, when Scottish surgeon James Lind used twelve crew members aboard his ship for an experiment. However, another forty years passed before the British navy made lemon juice mandatory. This was because of the expense and inconvenience of keeping fresh fruits on board all long voyages. British Royal Navy Captain James Cook was the first to prevent each crew he ever manned from contracting scurvy. This success was due to high standards for hygiene, and, more importantly, diet. Cook had a very low mortality rate aboard his ships, even of diseases unrelated to scurvy and Vitamin C.

            The impact ascorbic acid had as a cure changed the Age of Discovery. What if we had known the cure sooner? Would the world have turned out differently due to ships that could travel farther and more often? What if we had never discovered that ascorbic acid is the cure? Would we have ever successfully colonized America if the supply ships didn’t always return? While history likes to cheat Vitamin C of its rightful place, it is ever so important to recognize ascorbic acid’s impact both on our past and our bodies today.

 

My Opinion and the Authors’ Argument

            It is my opinion that Vitamin C is just as important now as it ever was. Our bodies still need ascorbic acid to be healthy and happy. Though it may go unrecognized by most, ascorbic acid has a massive effect on our daily lives. If anything, Vitamin C’s influence has gone up as more people have been educated about its usefulness.

            The authors’ argument is difficult to dispute because it makes so much sense. Le Couteur and Burreson explain thoroughly yet concisely how ascorbic acid is valuable to all humans. They outline how it has obviously impacted history and how it continues to be of importance. If they could provide more evidence, it would top the cake, but as it is I believe that their explanation clearly and effectively shows how Vitamin C has changed history.

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Ch 6: Silk and Nylon

Silk and Nylon, and Their Chemistry

Silk has been known for centuries as the luxurious fabric of the affluent. Its artificial counterpart, nylon, has a reputation as a similar, yet cheaper, alternative. The desirable traits of silk and nylon are all due to their chemical structures.

There are twenty-two amino acids, all different because of different “R groups” or “side groups” attached to the basic portion of the molecule. The simplest side groups are H (makes glycine), CH3 (makes alanine), and CH2OH (makes serine). These three smaller amino acids make up about 85% of silk’s structure, and give it the quality of smoothness. Chemists estimate that between 80 and 85% of silk is structured with an amino acid pattern glycine-serine-glycine-alanine-glycine-alanine. These chains lie parallel to adjacent chains, and when drawn together by cross-attractions, a pleated sheet structure is produced. This chemical structure gives silk it’s luster. The remaining 15% or so of amino acids in silk give it the properties of “sparkle” and ease of dyeing.

            Nylon, like silk, is a polyamide, which means that amide linkages hold together its polymer units. However, the structure of the polyamide is slightly different, which is what makes nylon artificial (not synthetic) silk. The resemblance of silk that chemist Wallace Carothers created became known as “nylon 66” due to the fact that each monomer unit in the molecule has six carbon atoms. The chemical similarities of silk and nylon give them many like properties, but they are not identical compounds and therefore do not have identical properties.

 

Silk and Nylon’s Impact on History

            The trade of silk between Asia and Europe opened major trade routes as early as the first century B.C. The Silk Road began with China exporting silk to the West, but it became much more. Distinguished cultures, revolutionary ideas, and new resources were transferred across the known world over the coming centuries. The beginnings of silk production in Europe also had groundbreaking consequences, because the silk economy was a foundation of the flourishing Renaissance in Italy.

            Nylon, the “artificial silk”, also changed the world significantly. It was initially used for products such as toothbrushes, women’s stockings, and military products. Nylon hosiery even became so popular that stockings become known as “nylons”. The use of nylon goods in World War I gave the United States an advantage over opposing countries without the product. By the 1950s, there were too many nylon products on the market to count. It even became known as the first “engineering plastic” after nylon’s property as a useful molding compound was discovered.

 

My Opinion on Silk and Nylon’s Impact

            Silk has been the iconic choice of the wealthy for thousands of years, and it maintains this status even now. Its beautiful luster, smooth feel, and easy comfort are unrivaled. These aspects of silk, which have made it well-known and sought-after, have also kept it in the spotlight. Silk may not hold the position it once did in Eastern trade, but it remains a very influential molecule. With so many molecules, the synthetic or artificial versions have completely replaced the original. This, however, has not been the case with silk and nylon. While nylon is extremely similar to silk, I feel that silk continues to impact the world today because of its unique beauty. This is not to say, though, that nylon hasn’t had an enormous influence.

Since its conception almost eighty years ago, nylon has become exceedingly popular. The diverse range of potential uses and ease of manipulation have kept nylon on top, and propelled it into more products than one would ever imagine. Nylon’s continuing usage in the United States and around the globe has proved that it deserves its title as one of the most versatile and useful molecules in the modern world.

 

The Author’s Argument

            I feel that Le Couteur and Burreson make a very strong case for the impact of silk and nylon’s chemical structures on the course of history. Especially with silk, they explain how the mix of smaller and larger amino acids gives it one-of-a-kind properties. The overwhelmingly popular characteristics of silk, which opened many complex trade routes, ultimately resulted in the sharing of other ideas and objects that certainly changed the world. I agree with Le Couteur and Burreson in their analysis of silk as a pivotal molecule in human history.

            While nylon has not been around as long as silk, I feel that the authors have correctly judged it to be very influential in the modern world. Le Couteur and Burreson do a good job of presenting past and present examples of nylon’s many uses. For example, the point of nylon’s part in World War I stood out to me as a strong argument. Overall, I am in accord with the authors’ views on the massive impact that the chemistry of silk and nylon have had on the world.

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