Bacterial Cell Division: The Cycle of the Ring
Bacterial cell division occurs through binary fission, a rapid process that allows bacteria to multiply quickly under favorable conditions. This involves DNA replication, septum formation, and cytokinesis to produce identical daughter cells. Understanding bacterial division is crucial for Class 11 Biology and NEET preparation.
This Story also Contains
- What is Bacterial Cell Division?
- Process of Division
- Role of FtsZ Protein and Z-ring
- Generation Time in Bacteria
- Bacterial Cell Division vs Mitosis
- Bacterial Cell Division NEET MCQs
- FAQs on Bacterial Cell Division
Prokaryotes are highly successful because of their potential to reproduce quickly in a favorable environment. By binary fission, a single prokaryotic cell divides into 2 cells, which then divide into 4, 8, 16, and so on. Under optimal conditions, many prokaryotes can divide every 1-3 hours. Some species can produce a new generation in only 20 minutes. Bacteria is one of the smallest living beings existing on the Earth. It multiplies by bacterial 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.
What is Bacterial Cell Division?
Bacteria is a prokaryotic organism and it multiplies by bacterial cell division, a form of mitosis (cell division). Bacterial cell division begins with a single bacterial cell and ends with two bacterial cells. The division starts when the cell volume 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. Genetic recombination is very rare, mostly offsprings are identical clones. Although variation can arise via conjugation, transformation, transduction.
Process of Division
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
The DNA cycle refers to the replication of the bacterial chromosome, where the circular DNA duplicates to ensure each daughter cell receives an identical copy. It is the genetic part of the cell cycle.
Division Cycle
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.
Role of FtsZ Protein and Z-ring
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.
Generation Time in Bacteria
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.
Bacterial Cell Division vs Mitosis
The major difference between bacterial cell division and mitosis is that bacterial cell division occurs majorly in prokaryotes like bacteria and mitosis occurs in eukaryotic organisms.
Feature | Bacterial Cell Division | Mitosis |
Type of organism | Prokaryotes (bacteria, archaea) | Eukaryotes (plants, animals, fungi, protists) |
DNA | Single circular DNA, nucleoid is present | Multiple linear chromosomes inside nucleus |
Spindle fibers | Absent | Present, formed from microtubules |
Key protein involved | FtsZ protein forms Z-ring for septum formation | Tubulin proteins form spindle apparatus |
End product | Two genetically identical bacterial cells | Two genetically identical eukaryotic daughter cells |
Speed | Very rapid (e.g., E. coli divides in ~20 minutes) | Slower, usually hours to days depending on cell type |
Bacterial Cell Division NEET MCQs
Q1. In a unicellular organism, cell division results in
Growth
Reproduction
Repair
All of the above
Correct answer: 2) Reproduction
Explanation:
.The primary purpose of cell division in unicellular organisms is reproduction. These organisms are made up of a single cell, and when that cell divides, a new, autonomous organism is created. Binary fission, budding, or multiple fission are some of the mechanisms that enable this procedure, which is referred to as asexual reproduction. For example, in yeast, budding is the creation of a tiny bud that expands and finally separates, but in bacteria, binary fission results in the splitting of one cell into two identical daughter cells. Numerous fission generates numerous daughter cells at the same time in certain protists, such as Plasmodium.
Hence, the correct answer is option 2) Reproduction.
Q2. Assertion: The cell cycle has evolved over time, allowing for increased regulation and complexity.
Reason: The cell cycle in eukaryotic cells is more complex than in prokaryotic cells, reflecting the evolution of more complex organisms.
Assertion and reason are both true, and reason is an accurate account of assertion.
Both assertion and reason are accurate, but reason does not adequately explain assertion.
The assertion is correct, but the reasoning is incorrect.
Both the assertion and reason are incorrect.
Correct answer:1) Assertion and reason are both true, and reason is an accurate account of assertion.
Explanation:
The cell cycle has evolved, becoming more complex and regulated as organisms evolved. Prokaryotic cells, such as bacteria, have a relatively simple cell cycle that involves DNA replication, segregation, and cell division. In contrast, eukaryotic cells, which make up complex organisms such as animals and plants, have a more complex cell cycle that involves several phases, including interphase, mitosis, and cytokinesis. The eukaryotic cell cycle is regulated by various proteins and checkpoints, ensuring the proper timing and execution of each phase. The assertion that the cell cycle has evolved is supported by the reason that the cell cycle in eukaryotic cells is more complex than in prokaryotic cells, reflecting the evolution of more complex organisms.
Hence, the correct answer is option 1) Assertion and reason are both true, and reason is an accurate account of assertion.
Q3. Cell cycle is
An orderly set of stages that take place between a cell divide and then the daughter cells also divide
The sequence of events by which a cell prepares itself for division
Both a and b
None of these
Correct answer: 3) Both a and b
Explanation:
The cell cycle, a vital eukaryotic process, involves stages leading to cell growth and division. It's divided into interphase and mitosis. Interphase has three key phases: G1, where cells grow and produce proteins; S phase, when DNA replication occurs; and G2, for final preparations before division. Mitosis consists of prophase, metaphase, anaphase, and telophase, followed by cytokinesis. This process is tightly controlled by checkpoints and specific proteins to guarantee precise cell division and function.
Hence, the correct answer is option 3) Both a and b.
Also Read:
FAQs on Bacterial Cell Division
What is binary fission in bacteria?
Binary fission is the primary method of reproduction in bacteria, where a single bacterial cell divides into two identical daughter cells. The circular DNA replicates, and the cell elongates before a cross-wall (septum) forms, separating the two genomes. Finally, the cell splits into two, each with a complete copy of genetic material. This process is asexual, rapid, and efficient, allowing bacteria to multiply quickly under favorable conditions.
What is the role of FtsZ protein?
FtsZ is a bacterial cytoskeletal protein that plays a crucial role in cell division. It assembles into a Z-ring at the center of the cell, which marks the future site of septum formation. The Z-ring recruits other proteins to form the divisome complex, guiding the synthesis of a new cell wall and membrane. Thus, FtsZ functions as a key regulator of binary fission and cytokinesis in bacteria.
What is bacterial generation time?
Generation time is the time taken by a bacterial cell to divide and produce two daughter cells, or the time required for a bacterial population to double. It varies among species and environmental conditions. For example, E. coli can divide every 20 minutes under optimal conditions, while Mycobacterium tuberculosis has a much longer generation time of 15–20 hours. Shorter generation times explain the rapid growth of bacterial populations.
How do bacteria reproduce?
Bacteria reproduce mainly by asexual binary fission. Some also use budding, spore formation, or fragmentation under special conditions. Apart from reproduction, bacteria can exchange genetic material by conjugation (plasmid transfer), transformation (uptake of DNA), and transduction (via bacteriophages), which increases genetic variation. These processes help bacteria adapt, survive harsh conditions, and develop resistance to antibiotics.
Frequently Asked Questions (FAQs)
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.
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 cell must identify the mid-cell site where the division occurs. Also, conditions such as pH and temperature should be ideal.
In a typical bacteria, the generation time is around 20 minutes.
Popular Questions
Directions for question :
M/s Deloitte Touche Tohmatsu Limited, one of the top four audit and accounting firms in the world with headquarters at London, UK, and with an operational presence in 153 countries, hires Management Trainees (MT) from all the premier management institutes of India thrice every year, in the months of January, May and September.
Each new group of Management Trainees (MT) have to go through a four month rigorous training schedule, after which they have to pass through a test consisting of a written assessment and a case-analysis. The top hundred ranked Management Trainees (MT) based on the performance in the test are confirmed as Management Executives (ME). The rest are given the opportunity of undergoing the training for four months one more time along with the next batch of Management Trainees (MT) and then passing through the subsequent test consisting of the written assessment and case-analysis. The Management Trainee (MT) who fails to get confirmed as a Management Executive (ME) the second time is fired.
The scatter-graph below depicts the number of Management Trainees (MT) at Deloitte taking the tests from January 2020 till May 2022, and the vis-à-vis hired Management Trainees (MT) at Deloitte who were fired :
It is also known that for the month of September 2019 at Deloitte, 96 hired Management Trainees (MT) failed to be confirmed as a Management Executive (ME) the first time, and that 36 hired Management Trainees (MT) were fired.
Question :
In which test did the minimum number of Management Trainees (MT) get confirmed as a Management Executive (ME) in the second attempt ?
September 2020
May 2021
January 2021
January 2022
Directions for question:
The bar-graph given below shows the foreign exchange reserves of Nepal (in million Rupees) from 2014 to 2021. Answer the following questions based on the graph :
Question:
What was the percentage increase (rounded to the nearest integer, if deemed necessary) in the foreign exchange reserves in 2020 over 2016 ?