Tag: biotechnology and genetic engineering

Useful antibiotics are often discovered using a screening process. To conduct such a screen, isolates of many different microorganisms are cultered and then tested for production of products that inhibit the growth of test organisms.They are tested for their selective toxicities and therapeutic activities, and the best candidates are examined and modified. Once the process is complete, the antibiotic must be extracted and purified to a crystalline product. The copies of genes coding for enzymes involved in the antibiotic production can be inserted into a cell, via vectors such as plasmids.

Scientic theories about the origin-of-life theories have historically been characterized by the chicken-and-egg problem of which essential aspect of life was the rst to appear, replication or self-sustenance. RNA, the other nucleic acid, contained building blocks very similar to DNA, so biologists recognized early that RNA could store information in its linear sequences. With the discovery in the 1980s that RNA molecules were capable of biological catalysis, a function till now ascribed to proteins alone, RNA took on the role of the single entity that could act as both chicken and egg. Within a few years of the discovery of these catalytic RNAs (ribozymes) scientists had formulated an RNA hypothesis that posited an early phase in the evolution of life where all key functions were performed by RNA molecules. 

Beverages of low alcoholic content (less than about 9% alcohol) are fermented from grains and are usually considered to be beers. Wines, on the other hand, are fermented to a higher percentage of alcohol (10 - 18% alcohol) and are usually fermented from fruit juice. Higher levels of alcohol kill or inhibit bacteria stopping spoilage as well as fermentation. Vodka, whiskey, and other alcoholic beverages with alcohol contents well above 20% are produced by distilling alcohol from a yeast-fermented beverage. Many liquors are produced by using distilled alcohol (as high as 95% alcohol) to extract various flavoring materials after which the resulting extract is diluted with water and often sugar to make a flavored alcoholic beverages. Unless the alcoholic content of the resulting beverage is well above 15%, the material will not be stable and may start to ferment or even decay in storage. Hence, most liquors are atleast 20% alcohol.

Barley contains the largest amount of enzymes necessary for converting starches to ferment sugars. Barley is commonly used in breads, soups, stews though it is primarily grown as animal fodder and as a source of malt for alcoholic beverages, especially beer.
Thus, the correct answer is option (D), 'Barley'.

Escherichia coli are Gram-negative, facultative aerobic bacteria. They are common inhabitant of human gut. These strains of E. coli are harmless. They form the part of the normal microbiota of the intestine. They live in symbiotic association. They benefit hosts by producing vitamin K$ _2$ and preventing colonization of the intestine with pathogenic bacteria.