The meaning and content of cell theory

1. Significance

1. Reveals the unity of cells and the unity of biological structure.

2. It reveals that there is a certain affinity between living things.

3. It marked the entry of biological research into the cellular level, which greatly promoted the biological research process and laid the foundation for Darwin's theory of evolution.

2. Main content

1. Cells are organisms. All animals and plants develop from cells and are composed of cells and cell products (it cannot be described as "all living things"). "They are all composed of cells and cell products" because viruses are not composed of cells.

In 1886, Mayer, a German working in the Netherlands, added water to the leaves of tobacco plants suffering from mosaic disease. Grinding and injecting its juice into the leaf veins of healthy tobacco can cause mosaic disease, proving that the disease is contagious. Through analysis of leaves and soil, Maier pointed out that tobacco mosaic disease is caused by bacteria. ).

2. All cells are basically similar in structure and composition.

3. New cells are derived from the division of existing cells.

4. Biological diseases are caused by cell dysfunction.

5. Cells are the basic units of structure and function of organisms.

6. Organisms reflect their functions through the activities of cells.

7. A cell is a relatively independent unit, which not only has its own life, but also contributes to the overall life composed of other cells.

Extended information:

1. Related history

Anthony van Leeuwenhoek’s 17th-century microscope had a magnification of 270 times.

In Germany in the 18th century, natural philosophy was very popular. Part of this system was to describe what they believed to be the typical units that made up the diversity of the organic world. Goethe believed that leaves were the typical unit structure of various plants, while Okun argued that vertebrae were the basic unit of the archetypal structure of animals in general.

Okun further believed that organisms were composed of mucous vesicles, or living units, that continued to survive after the death of the organism to which they temporarily belonged, forming part of another organism. In the early 19th century, such a view was quite popular and was combined with microscopic observations of plant and animal structures.

2. Discovery of Cells

Hooke's drawing of the structure of cork cells in his book "Micrograph".

In 1665, Robert Hooke discovered plant cells using a microscope for the first time and described them in his book Micrographia. But cells were not considered at that time to be independent, living structural units of the plant world.

In the early 19th century, the study of plant anatomy was resurrected, and German botanists Treviranus and von Maur recognized cells as the structural units of plants. In the 1820s, Amici and others in Italy developed improved achromatic microscopes, which allowed people to observe the details of organic cells.

A London doctor, Robert Brown, observed in 1831 that plant cells generally have a nucleus, but he did not attach much importance to his discovery. The Czech Purkinje used a microscope to observe the embryonic nucleus in a hen egg and pointed out that animal tissues in the embryo are composed of tightly packed cytoplasmic blocks, which are very similar to plant tissues.

Baidu Encyclopedia-Cell Theory