Complete the sentences

1. The cell is …

2. The name was given …

3. The cork slice reminded him …

4. The microscopic studies of … brought …

5. … lead to the cell theory.

6. It stated that …

4.7 Read and translate the following text without a dictionary and guess the meaning of the underlined words:

Very little can be seen in living cells with the ordinary light microscope. The structure of the cells has been made visible by various procedures: killing the cells, fixing their components in a stable condition, and staining these components so that their structural details may be observed. Cell material was embedded in a substance, which can be cut in very thin sections for viewing. The development of the light microscope has been paralleled by the development of method for preparing cells for study. By 1920 all the major components of cell which can be demonstrated with the light microscope have been described.

4.8 Read the text and fill in the gaps, using the words below:

What can you see when you examine different organs under the 1)…? One thing will quickly stand out. No matter what part of the body you examine, you will find 2)….They are the smallest living units of the body just as bricks are the smallest units of a brick wall. Like other animal cells, each has cytoplasm, a nucleus and a thin cell membrane. The cells of the body are built in such a way that they can do their 3)… best. For example muscle cells are long and elastic. 4)… cells are very sensitive. They have many branches which connect with other nerve cells or with muscles or 5)….

Cells are so tiny that countless numbers of them go into the 6)… of our bodies. Our body consists of many different kinds of cells. These cells make up our tissue, which make up the 7)…. A tissue is nothing more than a group of similar cells all doing the same job. We have nerve, muscle, bone and blood 8)… among others.

4.9 Translate the following passages and entitle them:

1. Cells, as seen under the light microscope or the electron microscope, are exceedingly complex structures. We find that these cellular arrangements have a functional significance and that specific cellular structures are associated with specific chemical components and specific biochemical properties. Surrounding the nucleus of the cell is the cytoplasm. Embedded within the cytoplasmic sap may be distinguished such structures as mitochondria, a network of partitions from which microsomes are derived, secretory granules and other inclusions, each being with a complex interns structure of its own. The cell is surrounded by a cell membrane.

2. The cell membrane is the surface of separation between the cell and its surrounding fluid; it may or not be differentiated histologically. In the region of the surface, or in the membrane itself, are complex enzyme systems, maintained from within the cell, actively transferring substances from the environment into the cell, actively extruding substances out of the cell.

3. The cell nucleus is the largest and densest of the structures isolated from an animal cell. A surrounding membrane regulates the exchange of materials between the nucleus and the cytoplasm. Within the nucleus can be seen spherical nucleoli and the chromatin threads which carry genes. The units of hereditary control are arranged along them. The characteristic compounds of nuclei is deoxyribonucleic acid, DNA carrying by virtue of their chemical structure, the genetically inherited information required for he maintenance of the whole cell.

Date: 2015-04-23; view: 891; Нарушение авторских прав