Lesson 3 Bacteria

Ex. 3.1 Words and word-combinations to the text

chlorophyll – хлорофилл

to magnify – увеличивать

sphere – шар

rod – палочка

spiral – спираль

ubiquitous – вездесущий, повсеместный

habitat – место расположения, естественная среда

fission – размножение путём деления клеток

to multiply – размножаться

dividing – деление

to thrive – буйно, пышно расти

germ – микроб

dot – точка

comma – запятая

string – верёвка, шнурок

chain – цепь

cluster – гроздь

benefit – извлекать пользу

intestine – кишечник

to digest – переваривать

yeast – дрожжи

mold – плесень

Ex. 3.2 Translate the following word-combination

green colouring matter –

compound microscope –

radioactive waste –

world's biomass –

quarter of a pound –

inviting ecological niche –

chief credit –

to be responcible –

diverse community –

complex carbohydrates –

organic compounds –

waste processing –

environmentally friendly –

relative ease –

Ex. 3.3 Read and translate the text

Bacteria

Bacteria are tiny one-celled plants, without green colouring matter /chlorophyll/, that can be seen only under a compound microscope that magnifies them from 600 to 1200 times. Typically a few micrometers in length, bacteria have a wide range of shapes, from spheres to rods and spirals. Bacteria are ubiquitous in every habitat on Earth, growing in soil, radioactive waste, seawater, and deep in the Earth's crust. There are approximately five nonillion (5x10³⁰) bacteria on Earth, forming much of the world's biomass.

At the moment you were born, all damp and wiggy; your body harbored no bacteria. But in hours they colonized this inviting ecological niche, arriving on the air, doctor's hands, in mother's milk. Today you carry about a quarter of a pound. Oldest of life–forms (for two billion years the only life on earth), bacteria are structurally the simplest, lacking the cell nucleus found in other microbes. Most reproduce by fission: they multiply by dividing. Bacteria thrive as the planet's most abundant, most varied, most versatile, and most useful organisms – and among its most deadly.

The discovery that bacteria cause disease was one of the greatest of all advances in medical science. Chief credit for the germ theory of disease goes to the French chemist, Louis Pasteur, and the German doctor, Robert Koch. Bacteria come in many different sizes but in three principal shapes: rod -or pencil -shaped bacteria, the bacilli, produce diseases like tuberculosis and leprosy; spherical or dot -shaped, the cocci; and spiral or comma -shaped, such as the corkscrew spirochete of syphilis or the cholera vibrio. The cocci come in pairs (diplococci), strings ar chains (streptococci), or clusters, like grapes (staphylococci). Typical diplococci are the gonococcus, cause of gonorrhea, and the pneumococcus, cause of pneumonia. Streptococci are responsible for “strep” infections, such as the sore throat that is often a forerunner of rheumatic fever. Staphylococci are often present in boils. We benefit from many bacteria living inside us. In the large intestine alone, a diverse community of a hundred trillion bacterial cells acts as a barrier against pathogens. These cells also produce nutrients that the intestinal wall absorbs, derived from food the small intestine cannot digest, mucous gel, secreted by goblet cells, and other bodily substances. Making up some 70 percent of the bacterial volume, Bacteroides and Eubacterium break down the complex carbohydrates from the whole grains, fruits, and vegetables. Other bacteria such as Acidaminococcus, Bifidobacterium, Butyrivibro, Coprococcus, Fusobacterium, Lactobacillus, Peptostreptococcus, and Ruminococcus, complete the breakdown of food. Bacteria, often Lactobacillus in combination with yeasts and molds, have been used for thousand of years in the preparation of fermented foods such as cheese, pickles, sauerkraut, vinegar, wine and yoghurt. The ability of bacteria to degrade a variety of organic compounds is remarkable and has been used in waste processing and bioremediation. Bacteria capable of digesting the hydrocarbons in petroleum are often used to clean up oil spills. Bacteria can also be used in the place of pesticides in the biological pest control. These pesticides are regarded as environmently friendly, with little or no effect on humans and wildlife. Because of their ability to grow and the relative ease with which they can be manipulated, bacteria are the workhorses for the fields of molecular biology, genetics and biochemistry.

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