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Biotechnology and Its Applications : PYQ Questions Solved
Q. The Taq polymerase enzyme is obtained from (NEET – 2016)
A. Thermus aquaticus
B. Thiobacillus ferrooxidans
C. Bacillus subtilis
D. Pseudomonas subtilis
Answer: A. Thermus aquaticus
Q. Which of the following is an endonuclease? (NEET – 2016)
A. DNase I
B. Hind II
C. Protease
D. RNase restriction
Answer: B. Hind II
Q. Which of the following restriction enzymes produce blunt ends? (NEET – 2016)
A. Hind III
B. Xho
C. Eco RV
D. Sal I
Answer: C. Eco RV
Q. Which of the following is not a component of downstream processing? (NEET – 2016)
A. Expression
B. Preservation
C. Purification
D. Separation
Answer: A. Expression
Q. A foreign DNA and plasmid cut by the same restriction endonuclease can be joined to form a recombinant plasmid using (NEET – 2016)
A. Taq polymerase
B. Polymerase III
C. Ligase
D. Eco RI
Answer: C. Ligase
Q. DNA fragments separated on an agarose gel can be visualized after staining with ______. (NEET – 2017)
A. Ethidium bromide
B. Bromophenol blue
C. Acetocarmine
D. Aniline blue
Answer: A. Ethidium bromide
Q. A gene whose expression helps to identify transformed cells is known as ______. (NEET – 2017)
A. Plasmid
B. Selectable marker
C. Structural gene
D. Vector
Answer: B. Selectable marker
Q. A single strand of nucleic acid tagged with a radioactive molecule is called (NEET – 2012)
A. Plasmid
B. Probe
C. Selectable marker
D. Vector
Answer: B. Probe
Q. There is a restriction endonuclease called Eco RI. What does ‘co’ part in it stand for? (NEET – 2011)
A. Coli
B. Colon
C. Cofactor
D. None of the above
Answer: A. Coli
Q. Agarose extracted from sea weeds finds use in ______. (NEET – 2011)
A. Spectrophotometry
B. Gel electrophoresis
C. PCR
D. Tissue culture
Answer: B. Gel electrophoresis
Biotechnology and its Applications : NEET Preparatiopn Notes
1. Biotechnology: Introduction
Biotechnology is the application of living organisms, cells, enzymes or biological systems to develop useful products and processes for human welfare.
Modern biotechnology mainly involves:
- Genetic engineering
- Recombinant DNA technology
- Molecular diagnosis
- Gene therapy
- Genetically modified organisms (GMOs)
- Production of vaccines and therapeutic proteins
1.1 Major Areas of Biotechnology
| Area | Major Application |
|---|---|
| Medicine | Insulin, vaccines, gene therapy |
| Agriculture | Bt crops, Golden Rice |
| Industry | Enzymes, fermentation products |
| Research | Gene cloning, transgenic organisms |
| Environment | Bioremediation and waste treatment |
Example: Production of human insulin using genetically modified bacteria is an important application of recombinant DNA technology.
2. Genetic Engineering
Genetic engineering is the deliberate modification of an organism’s genetic material using biotechnology techniques.
It may involve:
- Isolation of a desired gene
- Cutting DNA at specific sites
- Inserting the desired gene into a vector
- Introducing recombinant DNA into a host
- Selection of transformed cells
- Expression of the desired gene
The major technology behind genetic engineering is Recombinant DNA (rDNA) technology.
3. Recombinant DNA Technology
3.1 Meaning of Recombinant DNA
DNA obtained by joining genetic material from two different sources is called recombinant DNA (rDNA).
Example:
Human insulin gene + Bacterial plasmid
↓
Recombinant plasmid
↓
Introduction into bacteria
↓
Insulin production
3.2 Basic Steps of Recombinant DNA Technology
The general sequence is:
Isolation of DNA → Cutting → Amplification → Ligation → Introduction into host → Selection → Expression → Product recovery
4. Tools of Recombinant DNA Technology
Important tools include:
- Restriction enzymes
- DNA ligase
- DNA polymerases
- Cloning vectors
- Host organisms
- Selectable markers
- PCR
4.1 Restriction Enzymes
Restriction enzymes are enzymes that cut DNA at specific nucleotide sequences.
They are often called molecular scissors.
The specific DNA sequence recognised by a restriction enzyme is called its recognition sequence or restriction site.
Example: EcoRI
EcoRI recognises the sequence:
5′ — GAATTC — 3′
3′ — CTTAAG — 5′
It makes staggered cuts and produces sticky ends.
4.2 Palindromic Sequence
A DNA sequence that reads the same in the 5′ → 3′ direction on both complementary strands is called a palindromic sequence.
Restriction enzymes often recognise such sequences.
NEET Fact: Restriction enzymes recognise specific DNA sequences rather than cutting DNA randomly.
5. Sticky Ends
Restriction enzymes such as EcoRI may produce short, single-stranded overhangs called sticky ends.
These ends can form hydrogen bonds with complementary sequences on another DNA fragment.
Therefore, sticky ends make it easier to join DNA fragments from different sources.
Example:
Desired human gene
+
Plasmid vector with complementary sticky ends
↓
Base pairing
↓
DNA ligase joins them
6. DNA Ligase
DNA ligase is an enzyme that joins DNA fragments by forming phosphodiester bonds.
It acts like molecular glue.
Important distinction
Restriction enzyme → Cuts DNA
DNA ligase → Joins DNA
This distinction is frequently tested in NEET.
7. DNA Amplification by PCR
PCR (Polymerase Chain Reaction) is a technique used to produce a large number of copies of a specific DNA sequence.
A single target DNA sequence can be amplified into millions or more copies through repeated cycles.
7.1 Components Required for PCR
- Template DNA
- Primers
- dNTPs
- Taq DNA polymerase
- Suitable reaction buffer
- Mg²⁺ ions
7.2 Steps of PCR
1. Denaturation
- Double-stranded DNA is heated.
- Hydrogen bonds between complementary strands break.
- Two single DNA strands are produced.
2. Annealing
- Temperature is lowered.
- Primers bind to their complementary sequences on the template DNA.
3. Extension
- Taq DNA polymerase adds nucleotides to the primers.
- New DNA strands are synthesised.
The cycle is repeated many times.
Denaturation → Annealing → Extension
7.3 Taq DNA Polymerase
Taq polymerase is obtained from the thermophilic bacterium:
Thermus aquaticus
It can tolerate the high temperature used during DNA denaturation.
NEET Fact: Taq polymerase is used in PCR because it is thermostable.
8. Cloning Vectors
A cloning vector is a DNA molecule used to carry a foreign DNA fragment into a host cell and facilitate its replication.
Common vectors:
- Plasmids
- Bacteriophages
- Engineered viral vectors
8.1 Plasmid
A plasmid is:
- Small
- Circular
- Usually double-stranded
- Extra-chromosomal DNA
It is commonly found in bacteria.
8.2 Important Features of a Cloning Vector
| Component | Function |
|---|---|
| Origin of replication (ori) | Site from which replication begins |
| Selectable marker | Helps identify/select transformed cells |
| Cloning site | Site for insertion of foreign DNA |
| Vector DNA | Carries the desired gene |
Origin of Replication
The ori is the DNA sequence from which replication begins.
It also helps determine the copy number of the vector inside the host cell.
Selectable Marker
A selectable marker helps identify cells that have received the recombinant DNA/vector.
Examples:
- Antibiotic resistance genes
- Other selectable markers
9. Host Cells
A host cell receives recombinant DNA and allows it to replicate and/or express the desired gene.
Common hosts:
- Escherichia coli
- Yeast
- Plant cells
- Animal cells
Example
Recombinant plasmid → E. coli → Gene expression → Desired protein
10. Introduction of Recombinant DNA into Host Cells
Foreign DNA must be introduced into the host cell.
In bacterial systems, methods include:
- Transformation
- Electroporation
- Chemical treatment
Transformation: Uptake of foreign DNA by a competent bacterial cell.
After introduction, cells containing the desired recombinant DNA are selected.
11. Selection and Screening of Recombinants
Not every host cell successfully receives recombinant DNA.
Therefore, biotechnology uses:
- Selectable markers
- Screening techniques
to identify suitable recombinant cells.
Basic principle:
Host cells
↓
DNA introduction
↓
Selection
↓
Screening
↓
Recombinant clone
12. Production of Recombinant Proteins
After the desired gene is introduced into a suitable host:
Foreign gene → Transcription → mRNA → Translation → Protein
The host cell produces the desired recombinant protein.
The protein is then:
- Extracted
- Purified
- Processed
- Tested
- Formulated
This overall process is important in the production of therapeutic proteins.
13. Human Insulin Production
Insulin is a peptide hormone produced by the β-cells of the pancreatic islets.
It plays a major role in maintaining blood glucose levels.
13.1 Structure of Human Insulin
Mature human insulin consists of:
- A-chain
- B-chain
The two chains are connected by disulfide bonds.
13.2 Proinsulin
In pancreatic cells, insulin is initially produced as proinsulin.
Proinsulin contains:
- A-chain
- B-chain
- C-peptide
During maturation:
Proinsulin → Removal of C-peptide → Mature insulin
13.3 Recombinant Human Insulin
Recombinant DNA technology can be used to produce human insulin using microbial hosts.
A classical approach involves producing the A and B chains separately in bacteria and subsequently combining them to form functional insulin.
13.4 Importance
Recombinant human insulin:
- Can be produced on a large scale.
- Avoids dependence on insulin extracted from animal pancreases.
- Provides human insulin with the desired molecular structure.
NEET Fact: Mature insulin does not contain C-peptide; C-peptide is removed during insulin maturation.
14. Vaccine Production
A vaccine stimulates the immune system to develop protection against a particular pathogen or antigen.
Biotechnology has enabled production of:
- Recombinant vaccines
- Subunit vaccines
- Recombinant antigens
- Modern vaccine components
Basic principle
Antigen exposure → Immune response → Memory cells → Faster/stronger response on future exposure
Example: Hepatitis B Vaccine
Recombinant DNA technology has been used to produce Hepatitis B vaccine antigen.
A gene encoding the relevant viral surface antigen can be expressed in a suitable host such as yeast.
The purified antigen is then formulated into a vaccine.
NEET Fact: Recombinant Hepatitis B vaccine is a classic application of biotechnology.
15. Gene Therapy
Gene therapy is an approach in which genetic material is introduced, modified or otherwise manipulated to treat a genetic disorder or restore a defective biological function.
Main objectives:
- Replace a defective gene with a functional copy.
- Provide a functional gene product.
- Correct or reduce the effect of a genetic defect.
15.1 ADA Deficiency
Adenosine Deaminase (ADA) deficiency is a classical example discussed in biotechnology.
ADA deficiency can severely affect immune function.
Basic Gene Therapy Approach
- Patient’s cells are obtained.
- A functional ADA gene is introduced into suitable cells.
- Corrected cells are expanded.
- Corrected cells are returned to the patient.
Limitation
If corrected mature lymphocytes are used, they have a limited lifespan.
Therefore, the treatment may need to be repeated.
A more lasting approach may involve correction of suitable stem cells, because stem cells can give rise to long-lived cell populations.
NEET Fact: ADA deficiency is a classical example of gene therapy.
16. Genetically Modified Organisms (GMOs)
An organism whose genetic material has been deliberately modified using genetic engineering techniques is called a Genetically Modified Organism (GMO).
GMOs include:
- GM plants
- GM animals
- GM microorganisms
Major Objectives of Genetic Modification
- Insect resistance
- Disease resistance
- Herbicide tolerance
- Improved nutritional quality
- Increased productivity
- Stress tolerance
- Production of therapeutic proteins
17. Bt Crops
Bt crops are genetically modified crops containing genes derived from the bacterium:
Bacillus thuringiensis
These genes produce insecticidal proteins that can protect crops against specific insect pests.
17.1 Bt Cotton
Bt cotton is a major example of a genetically modified crop.
It contains specific cry genes derived from Bacillus thuringiensis.
These genes encode insecticidal proteins.
17.2 Bt Toxin
In the bacterium, Bt toxin is produced as an inactive protoxin/crystalline protein.
When a susceptible insect feeds on Bt plant tissue:
Bt protoxin enters insect gut
↓
Alkaline gut activates the toxin
↓
Toxin binds to receptors on midgut epithelial cells
↓
Pore formation and cell damage
↓
Insect death
17.3 Why Bt Does Not Normally Harm the Plant
The Bt gene is introduced into the plant so that the plant produces the insecticidal protein.
The toxin is specifically effective against susceptible insect pests under the appropriate biological conditions.
17.4 Advantages of Bt Crops
- Protection from specific insect pests.
- Reduction in crop damage.
- May reduce the need for some chemical insecticides.
- Helps protect crop yield.
NEET Fact: Bt toxin becomes active in the alkaline gut of susceptible insects.
18. Cry Genes
The insecticidal proteins of Bt crops are encoded by cry genes.
Different cry genes may target different groups of insect pests.
Example:
- Some Cry proteins are effective against lepidopteran insects.
- Others may target coleopteran or dipteran pests.
Therefore, the specific cry gene used depends on the target pest.
19. Golden Rice
Golden Rice is a genetically modified rice developed to produce increased amounts of β-carotene, a precursor of vitamin A.
β-carotene gives the rice its characteristic golden-yellow colour.
Importance
It was developed as a biotechnology-based approach to address vitamin A deficiency.
NEET Fact:
Golden Rice → β-carotene → Provitamin A
20. Transgenic Animals
Animals containing a foreign gene introduced into their genome are called transgenic animals.
They are useful in:
- Studying gene function
- Understanding human diseases
- Testing medicines
- Testing vaccine responses
- Studying biological processes
- Producing useful biological products
20.1 Transgenic Mice
Transgenic mice are widely used in biomedical research.
Applications:
- Cancer research
- Genetic disease studies
- Immune system research
- Drug testing
20.2 Transgenic Animals as Disease Models
A human disease-associated gene can be introduced or modified in an animal to create a model that helps scientists study:
Gene → Molecular change → Disease → Treatment
20.3 Production of Biological Products
Transgenic animals can be engineered to produce useful proteins in:
- Milk
- Blood
- Eggs
- Other biological fluids
These proteins can then be isolated and purified.
21. Rosie — Transgenic Cow
Rosie is a famous example of a transgenic cow.
Its milk was reported to contain increased levels of the human protein α-lactalbumin.
This example demonstrated the potential of transgenic animals for producing valuable proteins.
NEET Point: Rosie is a classic example of a transgenic animal used for production of a human protein.
22. Biotechnology in Healthcare
Major medical applications include:
- Recombinant insulin
- Recombinant vaccines
- Gene therapy
- Molecular diagnosis
- Therapeutic proteins
- Monoclonal antibodies
- Transgenic disease models
22.1 Molecular Diagnosis
Biotechnology allows diseases to be detected using molecular techniques.
Important techniques include:
- PCR
- ELISA
- DNA/RNA probes
- Molecular sequencing methods
PCR in Diagnosis
PCR can amplify a specific DNA sequence from a pathogen or patient sample.
This makes detection possible even when the target DNA is present in a very small amount.
ELISA
ELISA = Enzyme-Linked Immunosorbent Assay
It is based on antigen-antibody interaction.
It can be used for detecting:
- Specific antigens
- Specific antibodies
NEET Fact: PCR amplifies DNA, whereas ELISA is based on antigen-antibody interactions.
23. Biotechnology in Agriculture
Biotechnology is used to develop crops with desirable characteristics.
Major objectives:
- Insect resistance
- Disease resistance
- Herbicide tolerance
- Improved nutritional value
- Drought tolerance
- Salinity tolerance
- Better crop quality
Examples
| GM Crop/Product | Major Feature |
|---|---|
| Bt cotton | Insect resistance |
| Golden Rice | Increased β-carotene |
| Bt crops | Protection against specific insect pests |
24. Biosafety Issues
Biosafety refers to measures used to ensure that biotechnology applications do not cause unacceptable harm to:
- Human health
- Animals
- Plants
- Environment
- Biodiversity
Potential concerns include:
- Environmental effects of GM organisms
- Gene transfer to other organisms
- Development of resistant pests
- Effects on non-target organisms
- Biodiversity concerns
- Food safety
- Ethical concerns
- Intellectual property issues
24.1 Environmental Risk
Before widespread release of a genetically modified organism, its potential effects should be carefully assessed.
Important considerations:
- Stability of introduced gene
- Possible gene flow
- Effect on non-target species
- Ecological interactions
- Long-term environmental effects
25. Biopiracy
Biopiracy refers to the unauthorised or unfair commercial use of biological resources or traditional knowledge, particularly when the source communities or countries do not receive appropriate recognition or benefits.
It is an important issue for biodiversity-rich countries.
Examples Associated with India
Biopiracy and patent controversies have involved:
- Neem
- Turmeric
- Basmati rice
These cases highlighted the importance of protecting:
- Traditional knowledge
- Biological resources
- Community rights
- Fair benefit sharing
26. Neem Patent Controversy
Neem has been used traditionally in India for various purposes, including agricultural and medicinal applications.
Patent-related controversies concerning neem-based products highlighted the problem of attempting to claim exclusive rights over knowledge that already existed as traditional knowledge.
NEET Point: Neem is commonly cited as an example in discussions of biopiracy and traditional knowledge protection.
27. Turmeric Patent Controversy
Turmeric has traditionally been used in India for medicinal and household purposes.
A patent was granted in the United States concerning the use of turmeric for wound healing, but it was later challenged because the use was already part of traditional knowledge.
The case demonstrated the importance of prior art in patent law.
NEET Point: Turmeric is a classical example of a patent dispute involving traditional knowledge.
28. Basmati Rice Patent Issue
Basmati rice and its traditional characteristics have also been associated with intellectual property and patent-related controversies.
These discussions highlight the need to protect:
- Indigenous biological resources
- Traditional agricultural knowledge
- Geographical identity
- Farmers’ interests
29. Patents
A patent is a legal right granted for an invention, giving the patent holder exclusive rights over the invention for a specified period, subject to applicable law.
In biotechnology, patents may involve:
- New biological products
- Biotechnological processes
- Genetic technologies
- Pharmaceutical products
- Genetically modified technologies
29.1 Patent vs Biopiracy
| Patent | Biopiracy |
|---|---|
| Legal protection for qualifying inventions | Unfair/unauthorised exploitation |
| Based on applicable intellectual-property law | May involve traditional knowledge or biological resources |
| Provides exclusive rights for a limited period | May deny rightful recognition/benefit sharing |
30. Intellectual Property Rights (IPR)
Intellectual Property Rights protect creations and inventions of the human mind.
In biotechnology, important IPR concepts include:
- Patents
- Plant variety protection
- Geographical indications
- Protection of traditional knowledge
The purpose is to encourage innovation while balancing public and community interests.
31. Ethical Issues in Biotechnology
Biotechnology raises several ethical questions.
Important issues:
- Should genetically modified organisms be released into the environment?
- Could genetic modification affect biodiversity?
- Who should own genetic resources?
- How should traditional knowledge be protected?
- What are the limits of genetic manipulation?
- How should gene therapy be regulated?
Therefore, biotechnology requires a balance between:
Scientific progress + Safety + Ethics + Environmental protection
32. Important Biotechnology Terms for NEET
| Term | Meaning |
|---|---|
| Genetic engineering | Deliberate modification of genetic material |
| Recombinant DNA | DNA formed by joining DNA from different sources |
| Restriction enzyme | Cuts DNA at specific sites |
| DNA ligase | Joins DNA fragments |
| Vector | Carries foreign DNA into host |
| Plasmid | Small circular extra-chromosomal bacterial DNA |
| PCR | Amplifies specific DNA sequences |
| Taq polymerase | Heat-stable DNA polymerase used in PCR |
| Transgenic organism | Organism carrying an introduced foreign gene |
| Bt crop | GM crop containing Bt-derived insecticidal gene |
| Gene therapy | Genetic approach used to treat disease |
| Biopiracy | Unauthorised/unfair exploitation of biological resources or traditional knowledge |
| Patent | Legal protection for a qualifying invention |
33. Important NEET Concept Points
- Modern biotechnology is strongly based on genetic engineering and recombinant DNA technology.
- Restriction enzymes are used to cut DNA at specific recognition sites.
- Many restriction enzymes recognise palindromic sequences.
- EcoRI produces sticky ends.
- DNA ligase joins DNA fragments by forming phosphodiester bonds.
- Plasmids are commonly used as cloning vectors.
- A vector generally contains an origin of replication, selectable marker and cloning site.
- PCR is used to amplify a specific DNA sequence.
- PCR steps are Denaturation → Annealing → Extension.
- Taq DNA polymerase is obtained from Thermus aquaticus.
- Recombinant human insulin is a major application of biotechnology.
- Mature insulin consists of A and B chains connected by disulfide bonds.
- Proinsulin contains C-peptide, which is removed during maturation.
- Recombinant Hepatitis B vaccine is a classical biotechnology application.
- ADA deficiency is a classical example of gene therapy.
- Bt crops contain insecticidal genes derived from Bacillus thuringiensis.
- Bt toxin is activated in the alkaline gut of susceptible insects.
- cry genes encode Bt insecticidal proteins.
- Golden Rice is associated with increased β-carotene production.
- Transgenic animals are useful as disease models and for production of biological products.
- Rosie is a famous example of a transgenic cow.
- PCR is useful for molecular amplification and diagnosis.
- ELISA is based on antigen-antibody interaction.
- Biosafety deals with potential risks associated with biotechnology.
- Biopiracy involves unfair or unauthorised exploitation of biological resources or traditional knowledge.
- Neem, turmeric and basmati rice are commonly discussed in relation to biopiracy/patent controversies.
- Patents provide legal protection for qualifying inventions for a specified period.
- Responsible biotechnology requires consideration of health, environmental, ethical and intellectual-property issues.