Competent Cells

The bacterial cells which will take up the foreign DNA from the environment by a process called transformation are referred to as competent cells. Griffith first reported it in Streptococcus pneumoniae. In the case of wall alteration, E.coli cells are more likely to uptake the DNA. The cells are often made competent by salt and warmth shock therapy. The cells growing rapidly are often made competent more easily than those in other stages of growth. The cells may retain the acquired genetic information after the transformation procedure. The process is essentially used to introduce recombinant plasmid DNA into competent bacterial cells. This process does not require a donor cell but only a DNA in the surrounding environment.


Principle of Competent Cells

Competent cells have altered cell walls that allow the DNA to simply undergo it. Some cells got to be exposed to some chemical or electrical treatments to transform them into competent cells. Treatment with calcium ions is the standard method for the preparation of those cells. Electroporation is the process in which cells take up DNA.


Methods of Preparation of Competent Cells

Competence is achieved in two ways:

  • Natural Competence

  • Artificial Competence


Natural Competence

Bacteria take up DNA from the environment by transformation, conjugation, and transduction. By the process of transformation, the foreign DNA directly enters into the bacterial cell. For this, the cells need to be in a competent state.


Frederich Griffith was the primary one to get natural competence. He injected the smooth strain of pneumococcus in mice, and the mice died. This strain is therefore referred to as virulent strain. But the mice didn't die when injected with the rough strain (non-virulent strain). Heat-killing abolishes the virulent nature of the graceful strain. The heat-killed smooth strain and therefore the rough strain were mixed. The rough strain acquired the graceful phenotype and have become virulent. This suggests that a heat stable, non-living material obtained from the graceful strain facilitated transformation.


Artificial Competence

In this, the cells are permeable to DNA in the laboratory. The competent cells are often prepared artificially in two ways, namely:


Calcium Chloride: This method was proposed by Mandel and Higa. The bacterial cells were treated with salt then suddenly exposed to high temperatures. This is known as the heat shock treatment method.


Electroporation: During this technique, an electrical field is applied to the cells to extend their permeability. It is also known as electropermeabilization.


What are the Characteristics of Cells?

Some of the important characteristics of Cells are :

  • Cells help in providing structure and support to the body of an organism.

  • The cell interior comprises different individual organelles surrounded by a separate membrane.

  • The nucleus holds genetic information necessary for reproduction and cell growth.

  • Mitochondria is a double membrane-bound organelle that is mainly responsible for the energy transactions that is vital for the survival of the cell.

  • Lysosomes digest unwanted materials present in the cell.

  • Endoplasmic reticulum plays an important role within the internal organisation of the cell by synthesising selective molecules and processing, directing and putting them to their appropriate locations.


What are the Different Functions of a Cell?

A cell performs these major functions which are essential for the growth and development of an organism. Some of the vital functions of a cell are :

  • To provide support and structure to the cell.

  • To facilitate the growth mitosis.

  • To allow the transport of nutrients.

  • To aid in reproduction.

  • To help in energy production.

FAQ (Frequently Asked Questions)

Q1. Define Competent Cells.

Ans - The bacterial cells which will take up the foreign DNA from the environment by a process called transformation are referred to as competent cells.

Q2. Who First Reported About These Cells?

Ans - Griffith first reported it in Streptococcus pneumoniae.

Q3. What are the Principles of Competent Cells?

Ans - Competent cells have altered cell walls that allow the DNA to simply undergo it. Some cells got to be exposed to some chemical or electrical treatments to form them competent. Treatment with calcium ions is the standard method for the preparation of those cells. Electroporation is the process in which cells take up DNA.

Q4. What are the Characteristics of Cells?

Ans - Some of the important characteristics of Cells are :

  • Cells help in providing structure and support to the body of an organism.

  • The cell interior comprises different individual organelles surrounded by a separate membrane.

  • The nucleus holds genetic information necessary for reproduction and cell growth.

  • Mitochondria is a double membrane-bound organelle that is mainly responsible for the energy transactions that is vital for the survival of the cell.

  • Lysosomes digest unwanted materials present in the cell.

  • Endoplasmic reticulum plays an important role within the internal organisation of the cell by synthesising selective molecules and processing, directing and putting them to their appropriate locations.

Q5. Define Natural Competence.

Ans - Bacteria take up DNA from the environment by transformation, conjugation, and transduction. By the process of transformation, the foreign DNA directly enters into the bacterial cell. For this, the cells need to be in a competent state.


Frederich Griffith was the primary one to get natural competence. He injected the smooth strain of pneumococcus in mice, and the mice died. This strain is therefore referred to as virulent strain. But the mice didn't die when injected with the rough strain (non-virulent strain). Heat-killing abolishes the virulent nature of the graceful strain. The heat-killed smooth strain and therefore the rough strain were mixed. The rough strain acquired the graceful phenotype and have become virulent. This suggests that a heat stable, non-living material obtained from the graceful strain facilitated transformation.