Competent Host – For Transformation With Recombinant DNA: Competent Host refers to a living organism, such as bacteria or yeast that has been modified or treated in such a way that it can uptake and express foreign DNA molecules. These competent hosts are commonly used in the process of genetic transformation where recombinant DNA is introduced into the host organism.

Competent Host

A competent host is an organism that has the ability to take up and incorporate foreign genetic material, such as plasmids or DNA fragments, into its own genome. This ability to uptake foreign DNA is known as competence. They generally involve the activation of specific genes and the production of proteins that facilitate DNA uptake and integration. A competent host is essential because DNA is a hydrophilic molecule so it cannot pass through the cell membrane. Hence, the bacteria should be competent to accept the DNA.

Example

Escherichia coli (E. coli) is commonly used in genetic engineering because of its well-studied genetics and ease of cultivation. To make the bacteria competent for DNA uptake several methods can be used:

Chemical method

The cell is treated with a divalent cation of a specific concentration like calcium ion which increases the pore size in the cell wall and makes it more permeable to DNA. After that the cells are incubated with recombinant DNA on ice and then placed briefly at 42⁰C and again put on the ice this treatment is called Heat Shock Treatment, and it makes bacteria capable to take the recombinant DNA.

Physical method

Recombinant DNA is directly injected into the nucleus of the host, this is known as the microinjection method. In plants, a gene gun or biolistic method is used.

Transformation with plasmids

Bacteria can be made competent by utilizing specific plasmids that contain genes responsible for enhancing the uptake of foreign DNA. These plasmids are introduced into the bacterial cells, enabling them to take up recombinant DNA more efficiently.

Once the competent host cells have taken up the recombinant DNA, they can grow under specific conditions to allow for the expression of the inserted gene. This process is used to produce the protein of interest or study gene function within the host organism.

Mammalian cells can also be made competent and used for genetic transformation in different biotechnological applications.

FAQs on Competent Host

Q1: What is competency?

Answer:

It is the ability of a cell to take up foreign DNA.

Q2: Which method is used in plants to make the competent host?

Answer:

Gene gun or biolistic method is used in plants. In this method, cells are bombarded with high-velocity microparticles of gold or tungsten which are coated with DNA.

Q3: What are the examples of competent hosts?

Answer:

Bacteria, yeast, and mammalian cells are the example of competent hosts.

Q4: How can a host be made competent?

Answer:

Host cell can be made competent by CaCl₂ (calcium chloride) and heat shock treatment. In growing phase these cells become competent easily than the other stages of growth. After transformation the competent cells might be express the acquired genetic information.

Q5: What is a competent bacteria?

Answer:

Competent bacteria have the ability to take up and incorporate foreign DNA into their own genome. In other words, they have the capacity for natural genetic transformation. This ability allows bacteria to acquire new genetic material from their environment, including genes that may provide advantages such as antibiotic resistance or the ability to metabolize different substances.

Q6: Why is E. coli competent?

Answer:

E.coli becomes competent if the cell wall is changed. By calcium chloride and heat shock treatment, the E.coli cells can be made competent.