Binary Fission: Prokaryotic, Asexual, Reproduction, Definition, Steps & Examples

Binary fission is the most common asexual type of reproduction observed largely in prokaryotic organisms such as bacteria and certain protozoans. This topic is part of the Class 12 Biology chapter Reproduction. Understanding the concept of binary fission is important as it is asked frequently in competitive exams such as NEET, where biology is one of the main subjects.

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This Story also Contains

1. What is Binary Fission?
2. Types of Binary Fission
3. Difference Between Binary Fission and Multiple Fission
4. Binary Fission Mechanism
5. Binary Fission in Different Organisms
6. Advantages and Disadvantages of Binary Fission
7. Binary Fission and Evolution
8. Tips, Tricks and Strategies to Study Binary Fission for Exams
9. Recommended Video on Binary Fission

What is Binary Fission?

Binary fission refers to asexual reproduction in which one parent organism produces two identical daughter cells. It is common amongst prokaryotes, some eukaryotes, such as protozoa and certain algae. The process is very rapid under conditions that are favourable for multiplication.

Some of the general features of binary fission include the duplication of genetic material, cell elongation, and finally division into two new cells. There is no exchange or recombination of genetic material through binary fission, unlike in sexual reproduction; hence, the offspring will be identical to the parent.

The primary difference between binary fission and sexual reproduction is that binary fission has a low degree of diversity in its genes in comparison. Sexual reproduction combines the genetic materials from two parents; hence, genetically varied offspring are there to adapt well to changing environments. Binary fission produces clones, thus having the advantage in stable conditions but possibly at a disadvantage if the environment changes.

Also Read:

• MCQ Practice on Binary Fission
• Multiple Fission
• Reproduction in Organisms
• Asexual Mode of Reproduction

Types of Binary Fission

Binary fission may appear in different forms depending on the nature of the organism and the method of division.

Amoeboid Binary Fission

• It involves the division of the nucleus, followed by the division of the cytoplasm.

• This form of binary fission is generally used by the amoeba.

• The process begins with the elongation of the cell accompanied by the mitotic division of the nucleus.

• The cytoplasm constricts in the middle leading to the formation of two daughter cells.

• Example: Amoeba proteus.

Binary Fission in Bacteria

• Bacteria replicate their DNA before the cell divides.

• The cell elongates and the DNA molecules move to opposite poles.

• A septum forms in the middle of the cell, dividing it into two.

• The cell splits into two identical daughter cells.

• Example: Escherichia coli (E. coli).

Longitudinal Binary Fission

• The cell divides along its longitudinal axis.

• Common in flagellates.

• Example: Euglena.

Transverse Binary Fission

• The cell divides along its transverse axis.

• Common in ciliates.

• Example: Paramecium.

Multiple Fission

• Division of the nucleus several times before the division of a cell.

• Several daughter cells are produced from one parent cell.

• Important in parasitic protozoa such as Plasmodium.

Difference Between Binary Fission and Multiple Fission

The table below indicates the main difference between the binary and multiple fission:

Binary Fission Mechanism

Binary fission consists of three major steps: initiation, elongation, and separation.

Initiation

• Replication of DNA. Two copies of the exact same genetic material were made.

• The helical ends of each copy attach to areas on the cell membrane.

Elongation

• The cell grows and elongates.

• Chromosomes move to opposite ends of the cell, ensuring each daughter cell will receive a copy.

Separation

• A septum forms, beginning the division of the cell.

• The cell membrane pinches inward, splitting the cell into two daughter cells.

• The new cells are identical to the parent cell.

Binary Fission in Different Organisms

Binary fission varies across different types of organisms.

Prokaryotes

• Bacteria (E. coli): DNA replication followed by cell division.

• Archaea: A binary fission method identical to that of bacteria, but using unique enzymes and mechanisms.

Eukaryotes

• Protozoa (Amoeba, Paramecium): Binary fission is complicated, including mitosis.

• Algae (Chlamydomonas): A binary fission process that, although different, is similar in concept to protozoa.

Mitochondria and Chloroplasts

• Mitochondria and Chloroplast replicate themselves within the eukaryotic cells in a binary fission-like process, due to their prokaryotic ancestry.

Advantages and Disadvantages of Binary Fission

The advantages and disadvantages of binary fission are given below:

Advantages

• A rapid method of reproduction that allows a fast tempo of population increase.

• Does not require a mate, which simplifies the reproductive process.

• The daughter organisms are genetically identical, allowing successful traits to be passed on.

Disadvantages

• Low genetic diversity makes populations more vulnerable to changes in the environment.

• Inability to fight against diseases and other environmental factors.

Binary Fission and Evolution

Binary fission in evolutionary biology is important because this method of reproduction can increase the population to a very large extent in a very short period of time. However, binary fission does not have the same meritorious features of high population diversity seen in sexual reproduction. However, errors during DNA replication can lead to variations which would contribute to evolution over a period of time.

Tips, Tricks and Strategies to Study Binary Fission for Exams

Here are some tips and tricks to prepare for binary fission:

Mnemonic for the Steps of Binary Fission: "I Eat Delicious Sandwiches"

• I - Initiation (DNA replication starts)
• E - Elongation (cell grows and DNA moves to poles)
• D - Division (septum formation and cell splits)
• S - Separation (two identical daughter cells form)

Mnemonic for Types of Binary Fission: "Always Laughing, Transverse Turns"

• A - Amoeboid (example: Amoeba)
• L - Longitudinal (example: Euglena)
• T - Transverse (example: Paramecium)

Mnemonic for Characteristics of Binary Fission: "Fast Bacteria Always Duplicate Quickly"

• F - Fast reproduction
• B - Binary fission is a type of asexual reproduction
• A - Asexual (no exchange of genetic material)
• D - Duplicate DNA before division
• Q - Quick process under favourable conditions

Also Read:

Recommended Video on Binary Fission