Microorganisms

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.

POST-TEXT ASSIGNMENTS:

Exercise 7. Find corresponding equivalents:

Вільний кисень; сприятливий для розвитку; види бактерій; паличкоподібні бактерії; вигнуті або у формі коми; спіралеподібна бактерія; поживні речовини; прикріпити до поверхні; впливати на здатність бактерій; розмножуватися та ділитися; збільшуватися у розмірі; процес поділу; подвоюватися кожні 2 хвилини; умови навколишнього середовища; слизова оболонка; галузь мікробіології; причина смерті людини; перетравлювати їжу.

Exercise 8. Answer the questions:

– What conditions are favourable for aerobic microorganisms?

– What shape do cocci have?

– What bacteria are called bacilli?

– When do bacteria grow and multiple extremely rapidly?

– How do pathogens influence the human body?

– What diseases can be caused by bacteria?

– How can people use bacteria?

– What science studies bacteria?

Exercise 9. Match the terms with their explanations:

pathogen	(of an organism or process) depending on oxygen.
metabolism	(of an organism or process) requiring the absence of or not dependent on the presence of oxygen.
nutrient	the basic structural and functional unit of living organisms. It consists of a nucleus, containing the genetic material, surrounded by the cytoplasm in which are mitochondria, lysosomes, ribosomes, and other organelles. All cells are bounded by a cell membrane.
insulin	a protein hormone, secreted in the pancreas by the islets, that controls the concentration of glucose in the blood. Insulin deficiency results in diabetes mellitus.
anaerobic	any of the mineral substances that are absorbed for nourishment of an organism.
cytoskeleton	a network of fibrous proteins that governs the shape and movement of a biological cell.
aerobic	any agent that can cause disease.
cell	the sum total of the chemical processes that occur in living organisms, resulting in growth, production of energy, elimination of waste material, etc.

Exercise 10. 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
9. therapeutic 10. mucous 11. atmospheric 12. typhoid 13. microscopic 14. rod-shaped 15. parasitic 16. anaerobic 17. bacterial 18. human	2. organism 3. oxygen 4. microorganisms 5. bacteria 6. flora 7. association 8. fever 9. membrane 10. metabolism 11. proteins

Дата добавления: 2015-10-21