Bacteria mainly reproduce in the form of asexual binary division (fission), that is, when bacteria grow to a certain period, they gradually form a diaphragm between cells, which divides from a mother cell into two daughter cells of equal size. Cell division is a continuous process. When dividing at the same time, two daughter cells are formed, and a diaphragm is formed in the middle of the daughter cells, and the second division of bacteria begins.
Some bacteria divide their daughter cells to form a single thallus, and some bacteria do not separate to form a certain arrangement, such as streptococcus and streptococcus. The study of bacterial division process by electron microscope shows that bacterial cell division can roughly go through the process of nuclear material and cytoplasm division, diaphragm formation and daughter cell separation.
When bacterial cells divide, nuclear DNA is connected to the medium or cell membrane. At first, DNA replicates and moves to both ends of the cell. At the same time, the bacterial cell membrane sinks inward, forming a cytoplasmic membrane perpendicular to the long axis of the cell, so that the cytoplasm and nuclear matter are evenly distributed in the two daughter cells.
Secondly, the cell forms the transverse partition wall, and the cell membrane invades continuously, forming the plasma membrane of the daughter cell, while the cell wall of the mother cell gradually extends from the periphery to the center. Finally, the complete cell wall of the daughter cell is gradually formed. Then, the daughter cells divide to form two daughter cells of basically equal size.
Metabolism of bacteria:
Bacteria have many different metabolic patterns. Some bacteria only need carbon dioxide as a carbon source and are called autotrophs. Those who get energy from light through photosynthesis are called photosynthetic autotrophs. Those who rely on oxidized compounds for energy are called chemoautotrophs. Other bacteria rely on organic carbon as carbon source, which is called heterotrophic bacteria.
Photosynthetic autotrophic bacteria include cyanobacteria, which are the oldest known organisms and may play an important role in producing oxygen in the earth's atmosphere. Other photosynthetic bacteria carry out some processes that do not produce oxygen. Include green sulfur bacteria, green non-sulfur bacteria, purple sulfur bacteria, purple non-sulfur bacteria and Heliobacter. Nutrients required for normal growth include nitrogen, sulfur, phosphorus, vitamins and metal elements.