Exercise 2.Fill in the correct word or preposition from TEXT A

A cell__ ______ of the nucleus and the cytoplasm units. There are many_____ kinds of cells with many _____ functions. The nucleus is _____ from the cytoplasm by a delicate membrane. The nucleus _____ most of the DNA and is _____ only in the chromosomes of plants and _____. The giant molecules of _____ and _____ consist _____ nucleic acids. They are responsible ________ arranging the amino acids _____ proper sequences in the proteins. Enormous _____ have been made in the last 20 years ______ giving precise chemical ________on the structure and chemistry of the cell. If a researcher wants _________ a cell, he uses______________ techniques and methods.

Exercise 3. Match the following terms in (A) with their definitions In (B). Consult TEXT A if necessary.

Exercise 4 Find out topic sentences in each paragraphs of TEXT A and write a short summary making use of them.

Exercise 5. Match the following English words and word combinations in (A) with their Russian equivalents in (B) Consult TEXT A and a dictionary if necessary.

Exercise 6. First look through the synonymous verbs from TEXT Agiving special attention to the prepositions used after most of them. Then read the following sentences translating into English the Russian words given in round brackets.

1. Organic compounds (встречаются) only in living bodies.

2. The giant molecules of DNA (состоят из) two spiral strands.

3. Inorganic substances (образуют) the bulk of living as well as non-living matter.

4. Lipids in protoplasm (достигают) 13%.

5. Four of the five nitrogenous bases - adenine, thymine, guanine and cytosine - (соединяются c) the pentose sugar and the phosphate group (и в результате образуют) nucleotides.

6. Chemically, all carbohydrates have much in common. they (состоятиз) carbon, hydrogen and oxygen.

7. The speed of reactions in cells (зависит от) enzymes.

8. Some reactions that simply (не происходят) in a test tube proceed rapidly in the living system.

Exercise 8.Define the following terms translating into English the words in round brackets. Work in pairs according to the model:

A: Could you define the term "protein"?

В: I could give you the following definition of the protein.

PROTEIN is а (сложное) organic (соединение) formed from many units of amino acids (соединенных) by peptide (связями).

AMINO GROUP is a group of atoms (состоящая) of one nitrogen atom and two (атомов водорода), which (остается) unchanged in many organic (реакциях).

GENE is a length of DNA which (определяет) a characteristic in an individual.

DNA (находится) only in the chromosomes of (растений) and animals and (соответствующих) structures in bacteria and (вирусах).

GENETIC CODING is the process (посредством которого последовательность) of amino acids in protein (определяется) by the sequence of nucleotides in a molecule of (информационной) RNA.