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111 • DNA (Deoxyribonucleic acid). The discovery of the DNA was made by the Swiss physician Friedrich Miescher. It was frst called as a «nuclein» because it resides in the nucleus of a cell. DNA is the blue print of a person because it holds the instructions how to build up some of the components of the other various cells and tissues of the body. • The Human Retrovirus (HIV) . In the 1980s competing scientists Robert Gallo (the USA) and Luc Montagnier (France) separately discovered a new retrovirus later dubbed HIV (human immunodefciency virus), and identified i as the causative agent of AIDS (acquired immunodefciency syndrome). 2. Are these statements true or false? 1. Edward Jenner was the frst to inoculate people against smallpox. 2. Louis Pasteur proved that some diseases are caused bymicroorganisms. 3. X‑ray was discovered by a German physician. 4. Russian doctor Nikolai Lunin was the frst to isolate vitamins. 5. In 1930s insulin was still unknown. 6. Insulin controls the amount of blood sugar in the body. 7. Before World War II there was no antibiotic available. 8. DNA was discovered by a Swedish researcher. 9. HIV was discovered by a team of scientists from one country. 10. HIV can develop into AIDS. 3. Discuss the questions in pairs. 1. Can you remember any other medical discoveries? What are they? 2. When were they made? 3. What is the signifcance of these discoveries for science and medicine? Exercise 24 p. 95 Student B 1. The earliest dental flling was made of beeswax (пчелиный воск). 2. The frst electric toothbrush, the Broxodent, was invented in … in 1954. 3. The frst nylon bristled toothbrush with a plastic handle was invent‑ ed in the USA in 1938. 4. In … Europeans believed that tooth decay was caused by worms. 5. Orthodontic brackets were invented by Edward Angle in 1915. 6. …was frst added to toothpaste in 1956.