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THE PERIODIC TABLEINSIDE AN ELEMENTMAKING MOLECULESMOLECULES TODAY
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Chemists have created everything all that you will use today; from the toothpaste that you used this morning and the chair that you are sitting on now, to the pillow that you will sleep on tonight.

It is impossible to think of a world without the contribution of the chemical industry, from everyday items like shampoo and television, to major advances in medicine and energy.

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DNAMedicine has come a long way since the days when herbalists and folk remedies were the only option, but substances obtained from plants and fungi are still used when treating and preventing infections. Penicillin, one of the earliest and best known antibiotics, is a chemical produced naturally by a fungus called Penicillium, an ascomycete. This fungus feeds on rotting dead animal or plant material. It produces penicillin as a strategy to compete with the bacteria that also feed on dead organisms. Bacteria naturally grow and multiply faster than the fungus unless they are inhibited by this naturally occurring antibiotic.

Other common antibiotics such as streptomycin, neomycin and tetracycline also occur naturally. We can grow the fungi in culture and extract the antibiotics from them. These chemicals either destroy micro organisms or inhibit their growth. They are most effective against bacteria, but can also be useful in treating infections caused by other micro organisms such as viruses. Diseases caused by viruses can be more difficult to treat than those caused by bacteria. However, scientists are continually developing more and more effective antiviral agents.

Unfortunately antibiotics don’t always win the battle against micro organisms. Every time a bacterium reproduces there is a chance that a mutation occurs - a change in the DNA code of the bacterium. Most mutations are a disadvantage to bacteria, but some may give individual bacteria the ability to resist particular antibiotics. To compound this, the more we use antibiotics to treat infections, the more likely it is that resistant strains of bacteria evolve. Some species of bacteria - for example Mycobacterium tuberculosis which causes tuberculosis - have developed multi-drug resistance, making them particularly difficult to treat. Viruses can mutate faster than bacteria, so the problem of drug resistance is even greater with viral infections.

So where does the chemistry come in to the story?

Well, in the past we used to simply extract an antibiotic from a culture of fungus and use it to treat bacterial infections without worrying about resistance. Today, however, we are aware that micro organisms can develop resistance to our antibiotics. To combat this, research chemists working for pharmaceutical companies need to understand the chemical composition of naturally occurring antibiotics and exactly how they affect micro organisms. With this knowledge they can develop synthetic antibiotics that will treat previously resistant bacteria, and are more effective in the treatment of viruses. Where in the past, tuberculosis could be treated with penicillin, the treatment today involves a cocktail of several different drugs.

So how do research chemists develop these synthetic antibiotics?

The first step in the investigation of a naturally occurring antibiotic is finding out its chemical formula. Neomycin has the molecular formula C12H26N4O6. Streptomycin is C21H29N7O12. Tetracycline is C22H24N3O8. Penicillin is R-C9H11N2O4S where R is a side chain with several different possibilities. Sounds complicated, but that’s the easy bit! Next the chemists discover how these atoms were connected together into molecules - find out the structural formula. Then they find out how the molecules actually work: exactly which part of the antibiotic molecule interferes with the life of the bacterium. Each step in the process seems more challenging. Using this knowledge the chemists are able to develop synthetic chemicals that resemble or mimic the naturally occurring antibiotics. These are molecules with similar 3D shapes to one or other naturally occurring antibiotic. During this development, the synthetic antibiotics must be thoroughly tested to ensure that they are effective against bacteria or viruses and, importantly, that they have no harmful side effects on patients. Only when they have passed all the tests can they be licensed for medical or veterinary use.

It’s really important that we all act responsibly with these new antibiotics; just discontinuing treatment when we feel better is irresponsible. Even though we may think that we’ve recovered, a residual infection can give rise to mutated micro organisms, ones that have developed resistance to the antibiotic. Failure to follow the prescribed treatment can have the same result. If a patient is supposed to take the tablets 3 times a day but forgets to do so, they will have a lower concentration of the antibiotic in their bloodstream; low enough to allow some bacteria to survive and mutate.

So there you have it: chemistry doesn't just answer the big questions of history, but is vital to the world we live in, affecting some of the most important aspects of our daily lives.

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The synthesis of new polymers has revolutionised the 20th century. They can be seen in virtually every aspect of our everyday lives. Polymers occur naturally, but scientists have been making synthetic polymers since the early 1900s. They are in the clothes we wear, the packaging our food comes in, our furniture and the electrical equipment we use.

The word 'polymer' is derived from the Greek polys meaning 'many' and meros meaning 'part'. Polymers are very large molecules, with a very high molecular mass. Rubber, for example, is made up of huge molecules with thousands of covalently bonded atoms. These huge molecules consist of monomers that are linked together through a process called polymerisation. The types of synthetic polymers that are used in industry are continually changing: compare the different plastic bottles there are! Bacterial polymers have also been created: these are totally biodegradable, but they are currently very expensive to produce.

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What professions can chemistry lead to?

Scientist using fluorescent gel systemA degree in chemistry can lead to many diverse vocations including biochemistry, materials science, pharmacology and biotechnology. Less obvious careers range from being a patent examiner or water purification chemist, to food technologist or veterinarian. Alternatively, you could choose to become a colourist or perfumer! To find out more about careers in chemistry, visit Chemsoc, the Royal Society of Chemistry’s chemical science network.

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What other areas can you think of where chemistry is involved?

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