Biology · Biotechnology and genetic modification. The idea in plain words, the rules to remember, the mistake to avoid and a worked example, written and checked by Mega Lecture.
Biotechnology uses microorganisms and enzymes to make useful products. Yeast is a fungus. Without oxygen it respires anaerobically and changes glucose into ethanol and carbon dioxide. In bread the carbon dioxide makes the dough rise. In brewing and biofuel production the ethanol is the product.
Bacteria are useful because they reproduce very quickly, can make complex molecules, raise no ethical concerns, and have plasmids, small rings of DNA that can carry a new gene.
A fermenter is a large tank in which bacteria or fungi are grown to make products such as penicillin or insulin. Conditions are controlled so the microorganisms grow and their enzymes work at the best rate.
Students say high temperature "kills" enzymes. Enzymes are not alive: write that the enzyme is denatured, so its active site changes shape and it no longer works.
Answer: Carbon dioxide makes the dough rise; the ethanol evaporates during baking.
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