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MICROORGANISMS. A microorganism (from the Greek: "small" and "organism") or microbe is a microscopic organism


A microorganism (from the Greek: "small" and "organism") or microbe is a microscopic organism, which may be a single cell or multicellular organism. All the existing microorganisms can be divided into two main groups – aerobic and anaerobic. Aerobic microorganisms must have atmospheric free oxygen for their life and growth. However one knows that free oxygen is not favourable for the development of anaerobic microorganisms.

Most bacterial species are either spherical, called cocci (from Greek kokkos, grain, seed) or rod -shaped, called bacilli (from Latin baculus, stick). Some rod-shaped bacteria, called vibrios, are slightly curved or comma-shaped; others, called spirilla, can be spiral-shaped.

This wide variety of shapes is determined by the bacterial cell wall and cytoskeleton, and it is important because it can influence the ability of bacteria to acquire nutrients, attach to surfaces, swim through liquids etc.

The growing organism increases in size up to a certain limit and in due time divides. The process of division depends on the conditions of the environment. Under optimal conditions, bacteria can grow and divide extremely rapidly, and bacterial population can double as quickly as every 9.8 minutes.

If bacteria form a parasitic association with other organisms, they are classed as pathogens. Pathogenic bacteria are a major cause of human death and diseases and cause infections such as tetanus, typhoid fever, diphtheria, cholera and tuberculosis. Some organisms, such as Staphylococcus or Streptococcus, can cause skin infections, pneumonia, and meningitis.

Other bacteria are the essential part of the normal human flora and usually exist on the skin or mucous membrane without causing any disease at all.

Bacteria frequently secrete chemicals into their environment in order to modify it favourably. The secretions are often proteins and may act as enzymes that digest some forms of food. The understanding of bacterial metabolism and genetics allow the use of biotechnology for the production of therapeutic proteins, such as insulin.

The study of bacteria is known as bacteriology, a branch of microbiology.


Exercise 8. Choose the Noun from list B to modify the verb from list A so as to make sense. Translate the word combinations into the native language and make the sentences of your own:

List A List B
1. therapeutic 2. mucous 3. atmospheric 4. typhoid 5. microscopic 6. rod-shaped 7. parasitic 8. anaerobic 9. bacterial 10. human 1. organism 2. oxygen 3. microorganisms 4. bacteria 5. flora 6. association 7. fever 8. membrane 9. metabolism 10. proteins


Exercise 9. Fill in the gaps with the words and word-combinations from the box:

On 17 March 2013, _____ reported data that suggested microbial life forms thrive in the Mariana Trench, the_________ spot on the Earth. Other researchers reported related studies that __________thrive inside rocks up to 1900 feet (580 metres) below ________under 8500 feet (2590 metres) of ocean off the coast of the northwestern United States. _________ to one of the researchers,"You can find microbes everywhere — they're extremely adaptable to_____, and survive wherever they are."

According; microbes; conditions; deepest; the sea floor; researchers

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