Competent Cells - Principles And Methods Of its Preparation

Aug 03, 2023, 16:45 IST

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The topic “Competent Cells” will be covered in this article. Cell competence is the capacity of a cell to incorporate extracellular DNA from its environment. Competent cells are ready to employ bacteria with more easily adjustable cell walls, facilitating easier foreign DNA passage. Rapidly expanding cells are metabolically active, healthy, and alive. There are several competent cells on the market. Competent cells are bacteria that can convert into other organisms by absorbing foreign DNA from their environment.

This article will discuss the factors involving preparation methods, background, regulation, characteristics, functions, principles, and critical points of Competent Cells.

Introduction

Competent bacterium cells are those that, through a process called transformation, can take in foreign DNA from their environment. Griffith initially described it as Streptococcus pneumoniae. If the cell walls of E. coli cells are changed, the DNA will be taken up more readily. Calcium chloride and heat shock therapy can make the cells competent. Compared to cells in previous growth stages, those that divide quickly can be made more intelligent.

After transformation, the cells might express new genetic information. Recombinant plasmid DNA is primarily introduced into bacterial cells with the necessary competence using this method. This procedure does not need a donor cell; all that is needed is DNA from the environment.

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Methods of Preparation of Competent Cells

Natural Competence

By transduction, conjugation, and transformation, bacteria absorb DNA from their surroundings. Through transformation, the foreign DNA enters the bacterial cell directly. This can only occur when the cells are competent.

Frederich Griffith first discovered the concept of natural competence. When he gave mice the smooth strain of pneumococcus, the mice perished. As a result, this strain is referred to as a virulent strain. However, when the severe stress was implanted, the mice did not die (non-virulent strain). The smooth strain's infectious nature is eliminated by heat killing. The wild strain and the smooth strain were combined. The wild pressure changed its phenotypic to smooth and developed virulence. This shows that metamorphosis was facilitated by a non-living, heat-stable substance produced by the smooth strain.

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Artificial Competence

In this, DNA can pass through cells in a lab setting. There are two approaches to prepare competent cells, namely artificially:

• Calcium Chloride: Higa and Mandel proposed this approach. After being treated with calcium chloride, the bacterial cells were abruptly subjected to high temperatures. This kind of treatment is referred to as heat shock.
• Electroporation: In the microbiology procedure known as electroporation, or electropermeabilization, cells are subjected to an electrical field to improve the permeability of their cell membranes, enabling the introduction of chemicals, medications, electrode arrays, or DNA (also called electrotransfer). The electroporation technique is frequently employed in microbiology by delivering new coding DNA to modify bacteria, yeast, or plant protoplasts.

Background of Competent Cells

When Frederick Griffith demonstrated that the preparation of dead cells from a pathogenic bacterium contained a substance that might change related non-pathogenic cells into the pathogenic variety, he discovered natural competence. It was established in 1944 by Oswald Avery, Colin MacLeod, and Maclyn McCarty that this "transforming ingredient" was only pure DNA. This was the first proof that DNA carries a cell's genetic information.

Since then, various bacteria have been examined for natural competence, including Bacillus subtilis, Streptococcus pneumoniae (also known as Griffith's "pneumococcus"), Neisseria gonorrhoeae, Haemophilus influenzae, and individuals of the Acinetobacter group. The mechanics of DNA transport, the regulation of competence in various bacteria, and the role of competence in evolution are all active research areas.

Regulation of Competent Cells

Natural competence is controlled in laboratory cultures and frequently brought on by nutrient deficiencies or unfavorable circumstances. Although little is known about the control of competence in these bacteria's natural habitats, the specific inducing signals and regulatory machinery are far more flexible than the uptake mechanism.##

Transcription factors that control competence have been identified; one such transcription factor is sxy (also known as tfoX), which is controlled by a 5' non-coding RNA element. Conditions that promote competence and sporulation frequently co-occur in bacteria that may produce spores. As a result, competent cells are often present in cultures or colonies that contain sporulating cells.

Characteristics of Competent Cells

Competent cells have several essential features, such as:

• The construction and support of an organism's body are helped by cells.
• In the interior of the cell, distinct membranes enclose various organelles.
• The genetic material needed for cell growth and reproduction is stored in the nucleus.
• The double membrane-bound organelle known as the mitochondria is principally in charge of the energy exchanges required for the cell's survival.
• The lysosomes degrade unwanted cell components.
• By synthesizing specific chemicals, processing, and delivering them to their correct locations, the endoplasmic reticulum helps the cell's internal organization.
• By creating specific molecules, processing, and guiding them to their proper sites, the endoplasmic reticulum plays a significant part in the internal organization of the cell.

Functions of Competent Cells

These crucial processes, which are required for an organism's growth and development, are carried out by cells. The essential parts of a cell include:

• Giving the cell structure and support.
• Growing the mitosis
• To enable the transfer of nutrients.
• To facilitate reproduction.
• To help in energy production.

The principle of Competent Cells

Competent cells has modified cell walls that make DNA easily pass through them. Some cells must be subjected to specific chemical or electrical treatments to become competent. The typical technique for preparing these cells is to give them a calcium ion treatment. Additionally, bacteria can absorb DNA through a process known as electroporation.

Key Points of Competent Cells

• Competent cells are microorganisms that can quickly absorb foreign DNA from their environment through a process known as transformation. These cells can be easily found in commercial yeast and bacteria on the market.
• Competent cells operate under the premise that their cell walls have been modified to facilitate easier passage of DNA.
• These cells serve various purposes, including assisting in the growth of a cell's mitosis, allowing nutrients to be delivered, assisting in the reproductive process, and assisting in the production of energy.
• There are two ways to prepare competent cells: naturally and artificially.
• Genetics controls the competence of natural cells. The DNA of a naturally competent cell is not always integrated into the cell's genome.
• In the artificial method used in the lab, cells are permeable to DNA. Competent cells can be produced artificially using chemical and electroporation techniques.

Competent Cells: FAQs

Q1. Define Competent Cells.

Ans. Competent cells are bacteria that can convert into other organisms by absorbing foreign DNA from their environment. There are two types of competence: induced competence and natural competence. When a bacteria is naturally competent, it easily absorbs foreign DNA in its native surroundings.

Q2. Who first reported about these cells?

Ans. It was initially described by Griffith in Streptococcus pneumoniae. He initially identified the innate capability in bacterial cells. During the experiment, it was discovered that these cells underwent a process known as transformation in which they ingested foreign DNA from the outside environment. But when their cell walls were changed, E Colli cells were more likely to take in the DNA.

Q3. What are the principles of Competent Cells?

Ans. Competent cells have modified cell walls, which enable DNA to change simply. They had to undergo chemical or electrical treatments to make some cells competent. The typical technique for preparing those cells is to give them a calcium ion treatment. Cells take up DNA by a process called electroporation. Bacterial cells can be made into capable ones using the electroporation procedure.

Q4. Define Natural Competence.

Ans. By transduction, conjugation, and transformation, bacteria absorb DNA from their surroundings. The foreign DNA enters the bacterial cell immediately through the transformation process. Initially, only Frederich Griffith had innate talent. When he gave mice the smooth strain of pneumococcus, the mice perished.

Q5. How long can competent cells be stored?

Ans. Competent cells can be held at -20°C for seven days and at -70°C for 15 days, according to research on the relationship between competent cell storage period and transformation efficiency.