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In 1928, at St. Mary's Hospital, London, Alexander Fleming discovered penicillin. This discovery led to the introduction of antibiotics that greatly reduced the number of deaths from infection.
The discovery of penicillin was actually a mistake!
Fleming obtained an extract from the mold, naming its active agent penicillin. He determined that penicillin had an antibacterial effect on staphylococci and other gram-positive pathogens.
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HCl is an acid because of H+ ions
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Explanation: Without gene duplication, mutation of genes would not exist. This would prevent organisms from adapting to their environment, making survival much more difficult if not impossible.
Mutations present permanent and heritable changes in the genome. We distinguish gene and chromosome mutations. Mutations in the level of genes are called point mutations because only one to several nucleotides are changed. These processes are known as deletion, insertion, and substitution. Deletion presents a loss of nucleotides which changes DNA sequence. When new nucleotides are embedded in the DNA chain, it is known as insertion. Substitution implies the process where new nucleotides are inserted while the ones that were present in that specific spot in a DNA molecule are deleted.
Mutations can also appear in chromosomes altering their number and structure. There are four types of mutations - deletion, duplication, inversion, and translocation. In deletion, a whole or one part of a chromosome is lost. Duplication presents an extra copy of a whole or one part of a chromosome. In an inversion, parts of a chromosome change order, while in translocation a part of one chromosome detaches and then connects to another.
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DNA, or deoxyribonucleic acid, is the hereditary material in humans and almost all other organisms. The information in DNA is stored as a code made up of four chemical bases: adenine (A), guanine (G), cytosine (C), and thymine (T). <span>DNA bases pair up with each other, A with T and C with G, to form units called base pairs. Each base is also attached to a sugar molecule and a phosphate molecule. Together, a base, sugar, and phosphate are called a nucleotide. Nucleotides are arranged in two long strands that form a spiral called a double helix. The structure of the double helix is somewhat like a ladder, with the base pairs forming the ladder’s rungs and the sugar and phosphate molecules forming the vertical sidepieces of the ladder.</span>
