细胞科学 i Science 蔡国平
细胞科学 Cell Science （14） 蔡国平
814. Cell reproduction and the cell cycle
§14. Cell reproduction and the cell cycle
8 14 Cell reproduction and the cell cycle 14.1 Cell reproduction Countless divisions of a single-celled zygote produce an organism of astonishing cellular complexity and organiza- tion. Any individual cell is bound to die, because cells are subject to wear and tear as well as to accidents. 25 million cells are undergoing division each second in an adult human and blood cells renewed at the rate of about 100 million per minute. If an organism is to continue to live, it must create new cells at rate as fast as that at which its cells die and for some cells, cell division is a special active process that is responsive for a special physiological activity, for example, the reproduction of gonial cells and apical meristem cells of plants as well as the selective proliferation of lymphocytes in immuno-response
§ 14 Cell reproduction and the cell cycle 14.1 Cell reproduction Countless divisions of a single-celled zygote produce an organism of astonishing cellular complexity and organization. Any individual cell is bound to die, because cells are subject to wear and tear as well as to accidents. 25 million cells are undergoing division each second in an adult human and blood cells renewed at the rate of about 100 million per minute. If an organism is to continue to live, it must create new cells at rate as fast as that at which its cells die and for some cells, cell division is a special active process that is responsive for a special physiological activity, for example, the reproduction of gonial cells and apical meristem cells of plants as well as the selective proliferation of lymphocytes in immuno- response
Each dividing cell is called mother cell, and its descen dants are called daughter cells, which are to become mother cells in their cell division actually, passing along the same genes they inherited from their mother to yet another new cellular generation. Therefore, cell division is often referred to as cell reproduction. Cell reproduction is a process of cell proliferation by which cell numbers or cell population become often larger continually. Cell reproduction have mainly three types: amitosis, mitosis and meiosis. Cell proliferation may be controlled normal cell reproduction but may become malignant cell proliferation losing normal controlling. Cell growth includes two meaning, one is that cell size become larger during development, another is the increase of cell numbers by cell proliferation. In most cases the meaning of cell growth is equal to cell proliferation
Each dividing cell is called mother cell, and its descen- dants are called daughter cells, which are to become mother cells in their cell division actually, passing along the same genes they inherited from their mother to yet another new cellular generation. Therefore, cell division is often referred to as cell reproduction. Cell reproduction is a process of cell proliferation by which cell numbers or cell population become often larger continually. Cell reproduction have mainly three types: amitosis, mitosis and meiosis. Cell proliferation may be controlled normal cell reproduction but may become malignant cell proliferation losing normal controlling. Cell growth includes two meaning, one is that cell size become larger during development, another is the increase of cell numbers by cell proliferation. In most cases, the meaning of cell growth is equal to cell proliferation
1. Three broad categories of cells with different division activity within multi-cellular organism Lost the ability to undergo division remaining in: extreme specialization state until they die. E. g. nerve cells, muscle cells. or red blood cells Cells that normally do not divide, but can be induced to begin DNA synthesis by some appropriate stimulus. E. g liver cells lymphocytes Cells that normally possess continually a relatively high and level of mitotic activity. Gonial cells, bone marrow stem cells, epithelial cells, and apical meristem cell of plants
1.Three broad categories of cells with different division activity within multi-cellular organism: · Lost the ability to undergo division remaining in extreme specialization state until they die. E.g. nerve cells, muscle cells, or red blood cells. · Cells that normally do not divide, but can be induced to begin DNA synthesis by some appropriate stimulus. E.g. liver cells lymphocytes. · Cells that normally possess continually a relatively high and level of mitotic activity. Gonial cells, bone marrow stem cells, epithelial cells, and apical meristem cell of plants