Recombinant DNA Technology - Process and Applications


1 min read

Prelims: General Science

Mains: Awareness in the fields of IT, Space, Computers, robotics, nano-technology, bio-technology and issues relating to intellectual property rights.

Recombinant DNA technology (RDT), often referred to as Genetic Engineering, is an in-vitro (lab) method of manipulating genes (DNA fragments) by using a set of tools and techniques. The primary aim of RDT is to produce “Transgene (recombinant DNA) and its product (recombinant protein), to be applied across different fields of biotechnology.

The RDT is a continuously evolving technology due to the advancement in its tools and techniques, such as the discovery of the CRISPR-Cas9 gene editing tool.

Tools of Recombinant DNA Technology

The following are the tools employed in the process involved in Recombinant DNA Technology:

VectorThey are used as carriers to introduce foreign DNA into a host cell

- Plasmids (for example, pBR322, Ti Plasmid),

- YAC (Yeast Artificial Chromosomes),

- BAC (Bacterial Artificial Chromosomes),

- Viruses (Phages), etc.

Restriction EnzymesIt recognises specific DNA sequences and cleaves the DNA at the precise location

- EcoRI, HindIII, BamHI, etc

- CRISPR Cas9 ( used primarily nowadays)

- Zinc-Finger Nuclease (ZFN)

DNA LigaseIt joins together DNA fragments- T4 DNA Ligase
Selectable markersTo distinguish transformed cells from non-transformed ones- Antibiotic resistance genes, herbicide resistance genes, etc

Process involved in Recombinant DNA Technology

Recombinant DNA technology undergoes through the following steps:

recombinant dna technology

  • Isolation of Genetic Material: The extraction of genetic material is performed from the source organism’s DNA, such as bacteria, plants, or animals.
  • Selection of a Suitable Cloning Vector: Vectors are carrier molecules used to introduce rDNA into a host organism.
    • Plasmids, which are small, circular DNA molecules, are commonly used vectors. They can replicate independently within a host cell, allowing for the propagation of the foreign DNA.
    • The vectors can also be non-self replicating (for example, viral vectors). 
  • Cutting of DNA at Specific Locations: It uses the specialized enzymes known as restriction endonucleases (RE) or restriction enzymes, which recognize specific DNA sequences (recognition sites) and cleave the DNA at those precise locations.
    • The RE cuts the target DNA as well as Plasmid, producing "sticky ends" that are complementary to each other.
  • Joining of DNA Fragments by Ligation:
    • The isolated DNA fragments are combined with a vector, which is typically a plasmid or a viral genome modified to accept foreign DNA.
    • DNA ligase is used to catalyze the formation of phosphodiester bonds, effectively sealing the gaps and fusing the DNA fragments with the vector.
    • Now the rDNA is ready for gene transfer (for in-vivo gene cloning) or for the PCR. 
  • Gene Transfer: There are several methods which are employed in the process of Gene Transfer- physical, chemical, and biological. RDT uses the biological means of gene transfer.
    • Physical methods: Gene gun or Biolistics, Electroporation, Microinjection, etc., which make the direct entry of the rDNA into the host’s cell.
    • Chemical methods: Using Lipofection, calcium phosphate, etc. make it easier for the rDNA to enter into the host’s cell.
    • Biological methods: This is an indirect method of gene transfer, using vectors (for example, bacteria) as a means.
  • Gene Cloning: Once inside the host, the rDNA replicates itself independently (due to self-replicating plasmid). This is called Gene Cloning. It can also be done using the PCRmethod for amplifying a gene of interest.
  • Polymerase Chain Reaction (PCR): PCR is a tool that allows for the amplification of the target DNA sequences outside the cell. It needs much less time than the traditional cloning methods.
  • Selection and Screening of Transformed Cells: This step involves identifying and isolating cells that have successfully taken up the recombinant DNA.
    • Selectable markers, such as antibiotic resistance genes carried by the vector, are often used to distinguish transformed cells from non-transformed ones.
  • Validation of Recombinant DNA Integration: To ensure that the recombinant DNA has integrated into the host genome as intended, various techniques may be employed.
    • For example, nucleic acid hybridization, blue-white screening, etc.


Applications of Recombinant DNA Technology

Recombinant DNA Technology stands as a cornerstone of modern science with far-reaching applications across numerous fields.

  • Advancement in Medicine:
    • It enables the production of vital biopharmaceuticals, particularly therapeutic proteins like insulin, growth hormone, and clotting factors.
    • Customized Therapeutics enables the production of personalised medicines tailored to an individual's genetic makeup, leading to more effective and targeted treatments.
  • Gene Therapy:
    • It offers the potential to treat genetic disorders by replacing or repairing faulty genes.
    • It is helpful in treating a wide range of diseases, like cystic fibrosis, muscular dystrophy, and certain types of cancer.
  • Recombinant Vaccines: RDT can be used to develop vaccines for a variety of diseases, using vectors like bacteria, yeasts, viruses (phage), etc. 
  • Immunotherapy: RDT contributes to the development of immunotherapies for example, T-cell therapy, which harnesses the body's own immune system to target and destroy cancer cells.
  • Agricultural Advancements:
    • It is used to cultivate Genetically modified (GM) crops that have transformed agriculture. Example: BT cotton.
    • These crops possess traits like pest resistance, drought tolerance, and improved nutritional content.
  • Bioremediation and Environmental Protection:
    • Environmental biotechnology indicates that Genetically-modified microbes such as bacteria, yeast and filamentous fungi can remove heavy metals from aqueous solutions.
    • For example, Escherichia coli strain JM109 has the ability to remove mercury from contaminated water or soil.
  • Targeted Drug Delivery: 
    • It enables the design and production of drug-delivery systems that can precisely target specific tissues or cells within the body.
    • This increases the effectiveness of treatments while minimizing side effects.
  • Molecular diagnosis (RDT plus PCR):
    • It plays a critical role in diagnostic techniques, allowing for the detection of specific DNA sequences associated with diseases or pathogens.
    • It is helpful in early detection and monitoring of various conditions.
  • Industrial Applications:
    • It is used in the production of recombinant enzymes to produce sugar, cheese, biofuels, important chemicals, etc.

PYQs on Recombinant DNA Technology

Question 1: Recombinant DNA technology (Genetic Engineering) allows genes to be transferred (UPSC 2013)

  1. across different species of plants
  2. from animals to plants
  3. from microorganisms to higher organisms

 Select the correct answer using the codes given below.

  1. 1 only
  2. 2 and 3 only
  3. 1 and 3 only
  4. 1, 2 and 3

Answer: (d)

Question 2: With reference to recent developments regarding ‘Recombinant Vector Vaccines’, consider the following statements: (UPSC 2021)

  1. Genetic engineering is applied in the development of these vaccines.
  2. Bacteria and viruses are used as vectors.

 Which of the statements given above is/are correct?

  1. 1 only 
  2. 2 only
  3. Both 1 and 2
  4. Neither 1 nor 2

Answer: (c)

Question 3:‘Aerial metagenomics’ best refers to which one of the following situations?(UPSC 2023)

  1. Collecting DNA samples from air in a habitat at one go
  2. Understanding the genetic makeup of avian species of a habitat
  3. Using air-bome devices to collect blood samples from moving animals
  4. Sending drones to inaccessible areas to collect plant and animal samples from land surfaces and water bodies

Answer: (a)

Question 4:‘Microsatellite DNA’ is used in the case of which one of the following?(UPSC 2023)

  1. Studying the evolutionary relationships among various species of fauna
  2. Stimulating ‘stem cells’ to transform into diverse functional tissues
  3. Promoting clonal propagation of horticultural plants
  4. Assessing the efficacy of drugs by conducting a series of drug trials in a population

Answer: (a)

Question 5: With reference to the recent developments in science, which one of the following statements is not correct? (UPSC 2019)

  1. Functional chromosomes can be created by joining segments of DNA taken from cells of different species.
  2. Pieces of artificial functional DNA can be created in laboratories.
  3. A piece of DNA taken out from an animal cell can be made to replicate outside a living cell in a laboratory.
  4. Cells taken out from plasma and animals can be made to undergo cell division in laboratory petri dishes.

Answer: (a)

FAQs related to Recombinant DNA Technology

What is Recombinant DNA Technology?

Recombinant DNA technology is a process that involves altering and combining DNA molecules from different sources. This enables scientists to create hybrid DNA sequences with specific traits or functions.

What are the steps in Recombinant DNA Technology?

The seven key steps in recombinant DNA technology are Isolation of Genetic Material, Cutting DNA at Specific Locations, Joining DNA Fragments, Insertion into Host Cell, Selection of Transformed Cells, Validation of Integration, and Expression of Traits.

What are the different types of recombinant DNA?

There are several types of recombinant DNA molecules like Plasmids, Viral Vectors, Cosmids, Bacterial Artificial Chromosomes (BACs), Yeast Artificial Chromosomes (YACs), Expression Vectors, and Shuttle Vectors. Etc.

Why are bacteria used in recombinant DNA technology?

Bacteria are commonly used in recombinant DNA technology as they have relatively simple and well-understood genetic systems, making them easier to manipulate.

What are the benefits of recombinant DNA technology?

Recombinant DNA technology offers numerous benefits like it allows for the creation of genetically modified organisms with desired traits, such as disease resistance in crops or the production of therapeutic proteins.