How can bacteria reproduce so rapidly?
Bacteria can divide very rapidly. This image is of a growing colony of E. coli bacteria. In the right environment, a single E. coli can divide to form a colony of hundreds of bacteria in just a few hours.
Bacteria, being single-celled prokaryotic organisms, do not have a male or female version. Bacteria reproduce asexually. In asexual reproduction, the "parent" produces a genetically identical copy of itself.
Bacteria reproduce through a process called binary fission. During binary fission, the chromosome copies itself, forming two genetically identical copies. Then, the cell enlarges and divides into two new daughter cells. The two daughter cells are identical to the parent cell. Binary fission can happen very rapidly. Some species of bacteria can double their population in less than ten minutes! This process makes it possible for a tremendous bacterial colony to start from a single cell.
Are there male and female bacteria? Of course the answer is no. So, sexual reproduction does not occur in bacteria. But not all new bacteria are clones. This is because bacteria can acquire new DNA. This process occurs in three different ways:
- Conjugation: In conjugation, DNA passes through an extension on the surface of one bacterium and travels to another bacterium (Figure below). Bacteria essential exchange DNA via conjugation.
- Transformation: In transformation, bacteria pick up pieces of DNA from their environment.
- Transduction: In transduction, viruses that infect bacteria carry DNA from one bacterium to another.
Bacteria can exchange small segments of DNA through conjugation. Notice two bacterial cells are attached by a short extension. DNA can be exchanged through this extension.
- Bacteria reproduce by binary fission, resulting in two daughter cells identical to the parent cell.
- Bacteria can exchange DNA through the processes of conjugation, transformation, or transduction.
Use the resource below to answer the questions that follow.
- Asexual Reproduction at http://www.youtube.com/watch?v=DY9DNWcqxI4 (1:03)
- There are approximately 7 billion humans on the planet. How long would it take some bacteria to make 7 billion copies of themselves?
- Describe how bacteria reproduce?
- How do bacteria exchange DNA?
- What is binary fission?
- What is transformation involving bacteria?