Biotechnology is a branch of biology dealing with techniques of using living organisms or parts of it to develop products helpful for human beings. The European Federation of Biotechnology (EFB) uniquely defines it as “the integration of natural science and organisms, cells, parts thereof, and molecular analogues for products and services”. 

• This topic is of particular interest to all medical aspirants. At least 3-5 questions can be expected from this section in NEET 2021. 

• Pretty easy questions are framed from this section and you can score well in this section.

Tools of genetic engineering and the process of recombinant DNA Technology are the two very important topics from this section that need to be covered and understood properly. Read the article to get more information on the same with solved sample questions. 

Principles of Biotechnology

There are mainly two core techniques in Biotechnology, as follows,

1. Genetic engineering- It involves techniques that alter the composition of the genetic material and introduce these into target organisms, changing their phenotype.

2. Aseptic environment-It helps in maintaining a contamination-free environment to allow the growth of desired eukaryotic cells for the production of biotechnological products such as antibiotics, vaccines, enzymes, etc. in large quantities.

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Tools of Genetic Engineering

The primary tools required to carry out genetic engineering are restriction enzymes, polymerase enzymes, ligases, vectors, and the host organism.

Restriction enzyme- The molecular scissors used to cut the DNA to be introduced to the vector is called the restriction enzyme. The restriction site is a particular site on the DNA where the cut is made.

There are two types of restriction enzymes.

• Endonucleases- These make the cuts at specific positions within the DNA.

• Exonucleases- These remove nucleotides from the ends of the DNA.

Hind II was the first restriction endonuclease. It was then discovered that the DNA molecules where always cut at a particular point by recognizing a specific sequence of six base pairs. This specific base sequence is known as the recognition sequence.

The endonucleases perform its activity by

• Inspecting the length of a DNA sequence.

• Bind to the DNA.c

• Cut each of the two strands of the DNA at specific points.

Each restriction endonuclease recognizes a specific palindromic nucleotide sequence in the DNA. It is a sequence of base pairs that reads the same on the two strands when the orientation of reading is the same. To make it simpler, let’s take an example. The DNA sequence ACCTAGGT is palindromic as its nucleotide complement is TGGATCCA. On reversing the order of the nucleotides in the complement, gives the original sequence.

Restriction enzymes cut the strand of DNA a little away from the palindromic sites leaving single-stranded overhanging portions at the ends which are called sticky ends. Two DNA fragments are joined at their sticky ends using the enzyme DNA ligase.

Sample Question

Ques. What is the DNA segment of EcoRI?

1. GAATTC

2. CTTAAG

3. No Segment

4. No of these

Solution: The DNA segment of EcoRI is GAATTC, the palindromic sequence is CTTAAG.

Ques. The experimental proof for semi conservative replication of DNA was first shown in

1. Plant

2. Bacterium

3. Fungus

4. Virus

Solution: Semi conservative DNA replication was first shown in Bacterium Escherichia coli by Matthew Meselson and Franklin Stahl.

Must Read: 

• NEET Study Notes for Genetics
• NEET Study Notes for Ecosystems
• NEET Study Notes for Microbes in Human Welfare

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Gel electrophoresis and Cloning Vector

Gel electrophoresis: This technique separates the DNA fragments after cutting the DNA by endonucleases.Being negatively charged molecules these fragments can be separated by making them move towards the positive electrode under an electric field through a matrix of agarose gel. 

The DNA fragments separate according to their size through the sieving effect provided by the gel. These separated fragments appear orange in color after staining with ethidium bromide, followed by exposure to UV radiation. By elution, these separated bands of DNA are extracted from the agarose gel, and then they are used to construct recombinant DNA by joining them with cloning vectors.

Cloning vectors: A vector containing foreign DNA is called a recombinant DNA. Plasmid, for example, is capable of replicating autonomously within a suitable host. It is extrachromosomal genetic material often found in bacteria and also in eukaryotic organisms.

Following features are required to facilitate cloning of a vector,

• Origin of replication - This is a sequence from where the replication starts. A piece of DNA when linked to this sequence can be made to replicate within the host cells.

• Selectable marker- It helps in identifying and eliminating untransformed cells and permitting the growth of the transformed cells. Antibiotic-resistant genes like ampicillin, chloramphenicol, etc. are a suitable selectable marker for E.coli.

• Cloning sites- To link the alien DNA, the vector needs to have a single recognition site for commonly used restriction enzymes. The joining of alien DNA is carried out at a restriction site present in one of the two antibiotic-resistant genes.

Ques. What is insertional inactivation?

Solution: The inactivation of a gene upon insertion of another gene in its place or within its coding sequence is called insertional inactivation. This helps the selection of transformant and recombinant colonies in the selective antibiotic medium.

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Vectors for cloning in plant and animals

Agrobacterium tumefaciens, a pathogen of several dicot plants is able to deliver ‘T-DNA’ to transform normal plant cells into a tumor and direct these tumor cells to produce the chemicals required by the pathogen. The tumor inducing (Ti) plasmid of Agrobacterium tumefaciens is modified into a cloning vector. Similarly, retroviruses delivering desirable genes into animal cells are capable to transform normal cells into cancerous cells. So after that DNA fragment has been ligated into a suitable vector it is transferred into a bacterial plant or animal host to multiply.

Competent Host (for transformation with recombinant DNA)

• The DNA has to be made competent by treating them with a specific concentration of a divalent positive ion like calcium. 

• This increases their efficiency with which the DNA enters the bacteria through its cell wall. These bacteria are then subject to heat shock. 

• The competent bacterial cells are put into ice, incubated with the rDNA at 42°C and then put back into ice immediately. 

• This forces the recombinant DNA to enter the competent cells. Other ways include micro injection, biolistics or gene gun.

Check  Mobile Apps and Online Resources for Preparing NEET 2021

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Process of Recombinant DNA Technology

The following steps facilitate recombinant DNA technology,

1. Isolation of genetic material: To start the process, the DNA needs to be isolated by breaking open the cell membrane.Treating the cells with enzymes like lysozyme (bacteria), cellulase (plant cells), and chitinase (fungus) can help in carrying this out. The RNA and proteins are removed by treating with ribonuclease and protease respectively. The pure form of DNA procured through precipitation via chilled ethanol. This results in the collection of fine threads of DNA in suspension.

2. Cutting of DNA at specific locations: Agarose gel electrophoresis checks the progression of a restriction enzyme digestion. After cutting the source and the vector DNA, the cut out gene of interest from the two are joined using ligase enzyme. This prepares the recombinant DNA.

3. Amplification of gene of interest using PCR: Polymerase chain reaction (PCR) uses two sets of primers and the enzyme DNA polymerase to amplify the target gene. The enzyme extends the primers using the nucleotides provided in the reaction and the genomic DNA as template. For repeated amplification, a thermostable DNA polymerase (from Thermus aquaticus) is used.

4. Insertion of recombinant DNA into the host organism: Competent recipient cells take up the ligated DNA. Only transformed cells grow while the untransformed recipient cells die out.

5. Obtaining the foreign gene product: After cloning the targeted gene, the conditions are optimized to induce the expression of the target protein. This results in the production of recombinant protein.

6. Downstream processing: After large scale production of the expressed protein and before it is ready for marketing as finished product; processes like separation and purification are undergone. This is collectively referred to as downstream processing. Suitable preservation, thorough clinical trials, strict quality control testing follows thereafter.

Sample Question

Ques. What is the name of the enzyme obtained from Thermus aquaticus?

1. Taq polymerase

2. Cellulase

3. Thermus aquaticus

4. None

Solution: The enzyme is called Taq polymerase.

Must Read: 

• NEET Study Notes for Biomolecules
• NEET Study Notes for Reproduction
• NEET Study Notes for Biological Classification

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Applications of Biotechnology

Applications of Biotechnology in Agriculture

• Genetically Engineered Crops

• Example - Golden Rice, Bt. cotton

• Pest resistant tobacco plant

• Virus resistant plants

• Flavr Savr Tomato

Applications of Biotechnology in Medicine

• Production of antibiotics, vaccines, enzymes, and proteins

• Digestive enzymes

• Gene Therapy

• Molecular Diagnostics

• Transgenic Animals

Applications of Biotechnology in Industry

• Large scale production of fructose

• Production of biopesticide

• Production of aquatic species

Environmental Applications of Biotechnology

• Bioremediation

• Waste Management

• Energy Production

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Previous Year Questions with Answers

Ques 1. From the following statements identify the incorrect statement that describes the characteristics of the enzyme Restriction Endonuclease.

1. Enzyme cut DNA molecule at an identified position within the DNA.

2. Enzyme binds the DNA at specific sites and cuts only one of the two strands.

3. Enzyme cut the sugar-phosphate backbone at specific sites on each strand.

4. The enzyme recognizes a specific palindromic nucleotide sequence in the DNA.

Ans: B.

Ques 2. What is the correct order of steps in Polymerase Chain Reaction?

1. Denaturation, Extension, Annealing.

2. Annealing, Extension, Denaturation.

3. Extension, Denaturation, Annealing.

4. Denaturation, Annealing, Extension. 

Ans: D.

Ques 3. DNA fragments are

1. Negatively charged

2. Neutral

3. Either negatively or positively charged depending on their size

4. Positively charged. 

Ans: A.

Ques 4. During the gel electrophoresis, what is the criterion for DNA fragments movement on agarose gel? 

1. The smaller the fragment size, the farther it moves.

2. Positively charged fragments move to the farther end.

3. Negatively charged fragments do not move.

4. The larger the fragment size, the farther it moves.

Ans: A.

Ques 5. Stirred tank bioreactors have been designed for

1. Purification of product.

2. Addition of preservatives to the product.

3. Availability of oxygen throughout the process.

4. Ensuring anaerobic conditions in the culture vessel. 

Ans: C.

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Preparation Tips and Study Plan

NEET is not too far away. The revised examination date is 13th September 2021. It was known to all that the exams would be held in July but due to the ongoing pandemic, it has been delayed. By now the aspirants are prepared to appear for NEET. Follow these steps before the exams and you will excel.

• Know your syllabus

The Biology section has the most number of questions and hence, the maximum marks attached. 90 questions (45+45 in Zoology and Botany) come in the Biology part. Half of the total marks, that is, 360 out of 720, come from this part. So, it is wise that this section is prepared well. Check NEET Biology Syllabus

• Concentrate on weaker sections

It is not possible for everyone to be good at everything. Some are strong in one and weak in another. Be wise and chalk out the topics that you are strong in and the ones in which you are weak. Give importance to all topics. Do not skip any chapter just because you don’t like it or are weak in it. Seek help from your teachers regarding these chapters. Dedicate more time to the weak areas. Read How to Prepare Biology Topic Wise?

• Study Material

It is important that you refer the right books while preparing for any exam. Trueman’s Elementary Biology Volume I & II and A.C. Dutt for Botany are some useful books. Follow NCERT textbooks and ‘Objective NCERT at your Fingertips for NEET’, because about 80-85% of questions are framed from these. Avoid studying too many books; there are high chances of confusing things. Check NEET 2021 Important Books

• Study routine

Prepare a timetable for your study and adhere to it. Allot time for mock tests and evaluate your progress. Dedicate time to your weak points. Manage your time very wisely.

• Practice test papers

Practice previous year questions, sample papers, and mock tests available online or offline. This will help in time management under pressure, to understand the question pattern, their difficulty level, and chapter-wise weightage.

• Prepare notes

Prepare short notes so that you can revise them easily. Use analogies to retain more information. Revise these whenever possible; you are bound to remember the concepts.

• Take care of your health

It is necessary to take care of your health. Marathon study sessions can be stressful. Take scheduled breaks, listen to some music, or solve a puzzle, and come back. Maintain a regular sleep cycle; it will help you increase your concentration power.