Kettéhasítás

Kettéhasítás, also known as binary fission, is a fundamental mode of asexual reproduction in single-celled organisms, particularly bacteria and archaea. This process allows a parent cell to divide into two genetically identical daughter cells, ensuring the propagation of the species without the need for genetic recombination. The process typically involves several key stages: DNA replication, cell elongation, septation, and finally, cell separation.

During DNA replication, the single circular chromosome of the parent cell is copied, resulting in two identical copies. These copies then migrate to opposite poles of the cell, preparing for division. The cell elongates to accommodate the growing volume, and a septum begins to form between the two replicated chromosomes, effectively dividing the cell into two compartments. The septum continues to develop until it fully separates the cell into two distinct daughter cells, each containing one copy of the chromosome and a portion of the cytoplasm.

Kettéhasítás is highly efficient and rapid, allowing populations to grow exponentially under favorable conditions. The time it takes for a cell to divide, known as the generation time, varies depending on the species and environmental factors such as temperature, nutrient availability, and pH. For example, some bacteria, like *Escherichia coli*, can divide every 20 minutes under optimal conditions, leading to rapid population expansion.

Beyond bacteria, binary fission is also observed in certain eukaryotic organisms, such as some protists and algae, though the mechanisms and complexity of the process may differ. This mode of reproduction ensures genetic stability within a population while enabling rapid adaptation to changing environments through mutations that arise during DNA replication.