VII Find in the text pairs of synonyms and remember trhem:

Hereditary, alike, form, generate, compare, elementary.

VIII Paraphrase the sentences using synonyms:

1. Biologists generally believe that life arose on Earth in the form of very simple organisms, similar to prokaryotic cells, about 3.5 to 4 billion years ago.

2. According to the endosymbiotic theory, the ancestral eukaryote developed a rudimentary nucleus when the plasma membrane folded around the chromosome.

3. For example, both mitochondria and chloroplasts resemble bacteria in size and shape.

4. Further, these organelles contain circular DNA, which is typical of prokaryotes, and the organelles can reproduce independently of their host cell.

5. Moreover, mitochondrial and chloroplast ribosomes resemble those of prokaryotes, and their mechanism of protein synthesis is more similar to that found in bacteria .

IX Write a word or phrase from the box in the correct form in each gap to complete the sentences.

bully charity look into service sort out split up tease turn to

1. Mark seemed really happy before he and his girlfriend _____.

2. Ms Cramer really helped me _____ a few problems I had last year.

3. I won’t tolerate your _____ the other kids at school.

4. Our community offers many _____ to help teens and their families.

5. Now that I’ve heard of Helping Hand, I’m going to _____ their programmes right away.

6. It’s important to have someone you can _____ when you need to talk.

7. Do ever give money to _____?

8. When someone _____ you about your looks, it can really hurt your feelings.

18-20 Practical lesson

Rules of reading: The letter Xx

Word formation: prefix re-

Text: Microbial metabolisms

Assignments to do:

I Remember:

1. Xx is pronounced as [gz] before shock vowel sound: exam, exit

Xx is pronounced as [ks] in other cases: text, next

2. prefix re–means once more : recycle, retell

II Read the words according to the rules of reading of the letter “Xx”:

Complex, axe, axis, example, external, waxy, dioxide, box, maximum, fox.

III Read and translate the following words:

Recalculation, rethink, retransformation, recall, retransmit, retrain, retransplantation.

IV Read and translate the text microbial metabolism

Microbial Metabolism

The life-support processes of even the most structurally simple organism involve a large number of complex biochemical reactions. Most, although not all of the biochemical processes of bacteria also occur in eukaryotic microbes and in the cells of multicellular organisms, including humans. However, the reactions that are unique to bacteria are fascinating because they allow microorganisms to do things we cannot do. For example, some bacteria can live on cellulose, whereas others can live on petroleum. Through their metabolism, bacteria recycle elements after other organisms have used them. Still other bacteria can live on diets of such inorganic substances as carbon dioxide, iron, sulfur, hydrogen gas, and ammonia.

We use the term metabolism to refer to the sum of all chemical reactions within a living thing organism. Because chemical reactions either release or require energy, metabolism can be viewed as an energy-balancing act. Accordingly, metabolism can be divided in classes of chemical reactions: those that release energy and those that require energy.

In living cells, the enzyme-regulated chemical reactions that release energy are generally the ones involved in catabolism, the breakdown of complex organic compounds into simpler ones. Those reactions are called catabolic, or degradative, reactions. Catabolic reactions are generally hydrolytic reactions and they are exergonic. An example of catabolism occurs when cells break down sugar into carbon dioxide and water.

The enzyme-regulated energy-requiring reactions are mostly involved in anabolism, the building of complex organic molecules from simper ones. These reactions are called anabolic, or biosynthetic synthesis reactions, and they are endergonic. Examples of anabolic processes are the formation of proteins from amino acids, nucleic acids from nucleotides, and polysaccharides from simple sugars. These biosynthetic reactions generate the materials for cell growth.

The role of ATP in coupling anabolic and catabolic reactions is shown in Figure 7. Only part of the energy released in catabolism is actually available for cellular functions because part of the energy is lost to the environment as heat. Because the cell must use energy to maintain life, it has a continuous need for new external sources of energy.