1, there are genetic materials in the nucleus-chromosomes (the human body has 23 pairs of chromosomes); Chromosome consists of DNA and protein; DNA is genetic material, and fragments of DNA are called genes. Chromosome is the carrier of genetic material.
2. The cell is the basic unit of the structure and function of the organism, and the reason why the organism grows up from childhood is because of cell growth and cell division.
When cells divide, first the nucleus is divided into two, then the cytoplasm is divided into two, and finally a new cell membrane is formed, and plant cells also form new cell walls. Abbreviation: nuclear-cytoplasmic-membrane wall formation. When the nucleus divides, the chromosome changes most obviously.
3. Cells are the unity of matter, energy and information. The growth and development of animals and humans all start from a fertilized egg.
4. Cell differentiation: In the process of development, different changes occur in morphology, structure and physiological functions, which is called cell differentiation. Cells divide into tissues.
5. Tissue: The differentiation of cells is different.
Cell (English name: cell) has no unified definition. Generally speaking, cell is the basic structure and functional unit of an organism. As we all know, all living things except viruses are composed of cells, but the life activities of viruses are bound to be reflected in cells.
Generally speaking, most microorganisms such as bacteria and protozoa are composed of one cell, that is, single-celled organisms, while higher plants and animals are multicellular organisms. Cells can be divided into prokaryotic cells and eukaryotic cells.
However, it has also been suggested that it should be divided into three categories, that is, the ancient nucleus originally belonging to prokaryotic cells should be separated as a parallel category. The study of cells is called cell biology.
Cells are very small and can only be seen under a microscope, and they have different shapes. It is mainly composed of nucleus and cytoplasm, with cell membrane on the surface. There are cell walls outside the cell membrane of higher plants, plastids are often found in the cytoplasm, and chloroplasts, vacuoles and mitochondria are found in the body.
Animal cells have no cell wall, centrosomes often exist in cytoplasm, but not in higher plant cells. Cells have the functions of exercise, nutrition and reproduction.