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

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 and 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.

Types of Binary Fission

Binary fission may appear in different forms depending on the nature of the organism and the method of division. There can be different forms of binary fission depending upon the need and conditions. For example, Amoeboid Binary fission, Transverse binary fission, etc. Here are some forms of Binary Fission:

Amoeboid Binary Fission

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

• 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.

Bacterial Binary Fission

• 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.

• It is commonly seen in flagellates.

• Example: Euglena.

Transverse Binary Fission

• The cell divides along its transverse axis.

• It is common in ciliates.

• Example: Paramecium.

Multiple Fission

• The 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.

Binary Fission vs Multiple Fission

Binary fission involves the production of two identical daughter cells, on the other hand, multiple fission gives rise to the formation of many identical cells that possess the genetic material of their parent. The table below indicates the main difference between binary and multiple fission:

Steps of Binary Fission

Binary fission involves some basic mechanisms using which the formation of the daughter cell occurs. There are three major steps involved in binary fission: initiation, elongation, and separation. These steps are responsible for the success of reproductive attempts.

Initiation

• Replication of DNA and 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 is the process that occurs in many organisms with different mechanisms, some involve the use of enzymes while others by following self-replication techniques. All these techniques result in a successful reproduction and continuation of life. Binary fission varies across different types of organisms.

Prokaryotes

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

• Archaebacteria: 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 are semi-autonomous organelles that can replicate themselves within eukaryotic cells in a binary fission-like process, due to their prokaryotic ancestry.

Advantages and Disadvantages of Binary Fission

Binary fission has advantages and disadvantages of its own. Understanding both advantages and disadvantages is equally important to know the process of binary fission in detail. 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 variation makes populations more vulnerable to changes in the environment.

• Inability to fight against diseases and other environmental factors.

Role of Binary Fission in 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 that would contribute to evolution over a period of time.

Binary Fission NEET MCQs

Q1. The asexual method of reproduction by binary fission is common to which of the following?

i. Some eukaryotes

ii. All eukaryotes

iii. Some prokaryotes

iv. All prokaryotes

Choose the correct option from the following:

1. i and ii

2. ii and iii

3. i and iii

4. iii and iv

Correct answer: 3) i and iii

Not all Prokaryotes reproduce by binary fission. Other Asexual reproduction methods like multiple fission and spore formation, are also seen in prokaryotes. Eukaryotes reproduce through both asexual and sexual reproduction methods.

Hence, the correct answer is the option 3) (i) and (iii).

Q2. Transverse type of binary fission occurs in unicellular organisms like

1. Planaria

2. Paramecium

3. Euglena

4. Both a and b

Correct answer: 4) Both a and b

Explanation:

If the plane of division is at a right angle to the long axis of the animal, it is known as transverse binary fission. This phenomenon is usually occurring in Paramecium and Planaria. In transverse binary fission, the organism divides along a plane perpendicular to its length, resulting in two daughter cells of nearly equal size. This type of fission is a form of asexual reproduction, allowing rapid population growth in unicellular organisms like Paramecium and flatworms like Planaria. The process begins with the replication of the organism's nucleus and organelles, followed by cytoplasmic division. As the division occurs, the two daughter cells each inherit a copy of the genetic material. Transverse binary fission is efficient and ensures the production of genetically identical offspring. In longitudinal binary fission, the plane of fission is parallel to the long axis, as in Euglena, Vorticella and some corals.

Hence, the correct answer is option 4) Both a and b.

Q3. Read the following statements:

1. In binary fission, the parent body divides to form the reproductive units.

2. Longitudinal binary fission is seen in Paramecium.

3. Binary fission occurs through cytokinesis followed by karyokinesis.

4. Amoeba always divides through binary fission.

Choose the option with correct set of statements:

1. a, b & d

2. b, c & d

3. a, b, c, & d

4. None of the above

Correct answer: 4) None of the above

Explanation:

a) In binary fission, the parent cell undergoes division to produce two daughter cells, which are reproductive as they can further develop into fully functional organisms.

b) Paramecium undergoes transverse binary fission, which is a process distinct from longitudinal binary fission seen in organisms like Euglena.

c) The correct order in binary fission is karyokinesis preceding cytokinesis. This sequence guarantees the proper segregation of genetic content before the cell divides into two separate entities.

d) Amoeba typically reproduces by binary fission, but it has an alternative asexual reproductive method called encystment, which it employs under unfavourable conditions.

Hence, the correct answer is option 4) None of the options. (Only a is correct).

Also Read:

• MCQ on Binary Fission and its Types

• Asexual Reproduction in Animals

• Sporulation

FAQs on Binary Fission

What is binary fission in biology?

Binary fission is a type of asexual reproduction in which a single parent cell divides into two identical daughter cells. It is the simplest and most common method of reproduction in prokaryotes like bacteria and in some unicellular eukaryotes like amoeba, euglena and paramecium. Since it involves only one parent, the offspring are genetically identical clones of the parent.

What are the types of binary fission with examples?

The main types of binary fission are:

• Amoeboid binary fission: No fixed plane of division, e.g., Amoeba.

• Transverse binary fission: Division occurs across the transverse axis, e.g., Paramecium.

• Longitudinal binary fission: Division occurs along the longitudinal axis, e.g., Euglena.

• Multiple fission: Division of the nucleus several times before the division of a cell, e.g., Plasmodium

How is binary fission different from multiple fission?

In binary fission, the parent cell divides into two daughter cells after DNA replication (e.g., Amoeba). It is simple, quick, and usually occurs under favorable conditions. In multiple fission, the parent cell divides into many daughter cells simultaneously, usually inside a cyst. This occurs under unfavorable conditions as a survival strategy. Example: Plasmodium (malarial parasite), Algae. Thus, binary fission ensures rapid multiplication, while multiple fission ensures survival.

What are the steps of binary fission?

1. DNA Replication: The genetic material (DNA) is copied.

2. Cell Elongation: The cell grows in size and the DNA molecules attach to different parts of the membrane.

3. Cytokinesis: The cytoplasm divides, separating the two halves.

4. Daughter Cells: Two genetically identical daughter cells are formed, each with a complete set of DNA

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