Bacteria is one of the smallest living beings existing on the Earth. It multiplies by bacterial binary fission, a form of mitosis (cell division). In larger organisms, including humans, mitosis serves as the method of growth and replacement. However, in microscopic organisms like bacteria, it is the method of multiplication of the organism. Bacterial cell division begins with a single bacterial cell and ends with two bacterial cells. The division starts when the cell volume (content) increases beyond a maximum limit (critical mass). Circular DNA makes up the bacterial chromosome, and it is double-stranded. Cytokinesis and cell separation are involved in this process.
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A bacterial cell has a cell wall, cell membrane, inner cytoplasm, flagella (for movement), bacterial capsule and bacterial spore. The right temperature and pH are essential for bacterial reproduction. Proper nutrition, energy supply and the right amount of oxygen are essential for bacterial growth. The division process involves two steps:
DNA Cycle
Division Cycle
The DNA cycle involves DNA replication and the separation of chromosomes. The division cycle includes the cytoplasmic division and the separation of the cell into two daughter nuclei. In this process, the first step is the recognition of the mid-cell site. It is the division site where the boundary between the cells gets formed. The rigid outer layer (peptidoglycan) and the cytoplasmic membrane coordinate to make the division possible.
FtsZ is a protein required for making the division materials. It has a tubulin protein having a ring (Z-ring) at the location where the bacterial cell will divide. The ring is made of smaller subunits of the FtsZ filaments. These filaments tighten as they pull against one another, which results in division. The features of such a division are:
The double-stranded DNA gets split to form complementary strands during the replication process. It has two identical DNA strands (double-stranded).
The cell membrane forms a septum that transversely spreads across the entire cell.
The cell gets split into daughter cells, and each receives one double-stranded DNA. The cell wall forms around each daughter cell through the development of the Z-rings.
The other cell features like ribosomes, DNA rods, and plasmids then form in each bacterial cell.
It is the time required for a bacterial cell to produce two identical daughter cells under ideal conditions (pH, temperature, and nutrition). In most bacteria, generation time is around 20 minutes. In some species, it can go up to 24 hours. The depletion of nutrients, formation of harmful byproducts, and other unfavourable conditions stop the bacterial division process.
In a typical bacteria, the generation time is around 20 minutes.
The cell must identify the mid-cell site where the division occurs. Also, conditions such as pH and temperature should be ideal.
FtsZ protein is required for the division process since it forms the Z-ring at the site where division will take place. It has a tubulin-like structure.
E-coli (Escherichia coli) is a common rod-shaped bacteria.
The DNA replicates first and moves towards opposite sides. The mid-cell site is identified, and the septum forms throughout the cell. The cell finally divides into two identical nuclei and forms other cytoplasmic structures like plasmids.
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