As you have learned, there are several types of asexual reproduction, which involves an organism becoming two organisms. For example, a potato, which is a tuber, produces another potato by vegetative reproduction. In this type of asexual reproduction, a modified stem or root of the parent plant grows offspring that stay attached to it. But all of the different forms of asexual reproduction have a common result: a new organism that is genetically identical to its parent. What does it mean to be genetically identical? It means that the new offspring has the same DNA as its parent. Asexual reproduction by binary fission demonstrates this process clearly, as modeled in the illustration below of a bacterium becoming two bacteria.
An illustration shows four stages of the binary fission in bacteria.
Source: Amit John. Pearson India Education Services Pvt. Ltd
The first stage shows a cell with a DNA inside the nucleus. The second stage shows the two ends of the cell’s DNA going to opposite sides of the cell, and the cell starts to grow larger and develop more organelles and more cytoplasm. The third stage shows the cell starting to divide, and the DNA separates into two separate strands, one on each side of the cell. A membrane starts to form in the middle of the cell. The fourth stage shows the cell splitting in half producing two identical daughter cells.
For bacteria, binary fission occurs in four stages. In the first stage, the cell prepares to split in two. Its DNA uncoils and then replicates. In the second stage, the two ends of the cell’s DNA go to opposite sides of the cell, and the cell starts to grow larger and develop more organelles and more cytoplasm. In the third stage, the cell starts to divide, and the DNA separates into two separate strands, one on each side of the cell. A membrane starts to form in the middle of the cell. In the fourth and final stage, the cell splits in half, and the parent cell has produced two identical daughter cells.
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