Q.Mention the chemical change that proinsulin undergoes, to be able to act as mature insulin.
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🔒 Start your 14-day free trial to unlock the full solution →Concept understanding — Recombinant Protein Therapeutics
Imagine you need a specific medicine—say, insulin for diabetes—but the only way to get it used to be from the pancreas of cows or pigs. That was expensive, risky (animal proteins could trigger allergies), and never quite identical to human insulin. Now, we can take the human gene that makes insulin, put it into a harmless bacterium or yeast, and let that microbe churn out perfect human insulin in huge vats. That is the core idea of recombinant protein therapeutics.
Recombinant means "made by combining DNA from different sources." Protein therapeutics means "a protein used as a medicine." So, recombinant protein therapeutics are medicines that are proteins, made by genetically engineered living cells, to treat or prevent disease.
The NCERT textbook (Class 12 Biology, Chapter 12, Biotechnology and its Applications) introduces this under "Biotechnological Applications in Medicine." It specifically mentions human insulin (Humulin) as the first recombinant therapeutic approved for human use. The textbook explains that the human insulin gene was inserted into E. coli bacteria, which then produced insulin identical to our own.
How does it work, step by step?
- Identify the gene that codes for the therapeutic protein (e.g., the gene for human insulin, growth hormone, or clotting factor).
- Insert that gene into a "vector" (a carrier DNA, often a plasmid from a bacterium) using restriction enzymes and DNA ligase.
- Introduce the vector into a host cell (usually E. coli bacteria, yeast, or mammalian cells). This host cell is now "transformed" – it carries the human gene.
- Grow the host cells in large fermenters. As they multiply, they follow the human gene's instructions and produce the human protein.
- Purify the protein from the culture. The final product is a pure, human-identical therapeutic protein, free from animal contaminants.
Why does this matter? (The "why" for a commerce/humanities student)
- Safety and Efficacy: Because the protein is exactly human, the body rarely rejects it. No risk of animal viruses or allergic reactions to animal proteins.
- Scalability: You can produce massive quantities in a lab, independent of animal supply. One batch of engineered bacteria can make more insulin in a day than thousands of pig pancreases.
- Cost (eventually): While initial R&D is expensive, mass production drives down cost, making life-saving drugs accessible to more people.
- New Treatments: It enables therapies that were impossible before—like monoclonal antibodies for cancer, or erythropoietin for anaemia in kidney patients.
The NCERT textbook emphasises that recombinant therapeutics are "relatively free from risk of infection and immune response" compared to products extracted from animals or human cadavers. This is the single biggest advantage: purity and human compatibility.
Examples you should know (from NCERT and common knowledge) …
Insulin is first made as a longer precursor, pro-insulin, which must be processed before it becomes functional — a key example in the NCERT Class 12 Biology chapter on biotechnology and its applications (genetically engineered insulin). …
Pro-insulin becomes mature insulin by the removal of the C-peptide (the connecting peptide), leaving the A and B chains linked by disulphide bonds.
Concept. Insulin is a peptide hormone made of two short polypeptide chains, A and B, held together by disulphide bridges. In humans (and mammals) it is synthesised first as a pro-hormone (pro-insulin) that needs processing to become fully mature and functional.
Why the change is needed. Pro-insulin contains an extra polypeptide stretch — the C-peptide — in addition to the A and B chains. This extra peptide is not present in the mature, functional hormone.
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- AP EAPCET 2026Set ap-2026-05-19-AN1 markMCQQ.Assertion (A): Cloned DNA are utilized in the commercial synthesis of hormones like insulin, interferon. Reason (R): Human insulin DNA sequences has two chains of A and B. They can be produced separately in E.coli and by creating disulfide bond human insulin can be formed (A) Both (A) and (R) are correct and (R) is the correct explanation to (A) (B) Both (A) and (R) are correct but (R) is not correct explanation for (A) (C) (A) is correct (R) is wrong (D) (A) is wrong (R) is correct
›Reveal solutionSolution
Recombinant human insulin (e.g., Humulin) really is made exactly as R describes — separate E. coli-expressed A and B chains joined by disulfide bonds — which is a valid explanation of why cloned DNA underlies commercial hormone production. Answer: (A).
Concept and Intuition
Before recombinant DNA technology, insulin for diabetics was extracted from slaughtered cattle/pig pancreases — a limited, expensive, and mildly immunogenic (non-human) source. Genetic engineering solved this by producing human insulin directly: since human insulin's mature form has two polypeptide chains (A chain and B chain) linked by disulfide bonds, Eli Lilly's approach (marketed as Humulin) prepared two separate DNA sequences corresponding to the A and B chains, inserted each into plasmids, and expressed them separately in E. coli. The two chains were then extracted and combined in vitro, allowing disulfide bonds to form correctly, yielding functional human insulin identical to the natural hormone.
Step-by-Step Solution
- Assess assertion (A): cloned DNA is used to make hormones like insulin and interferon commercially — this is a true, well-documented application of biotechnology. A is correct.
- Assess reason (R): it describes the actual two-chain, separate-expression, disulfide-bond-formation method used for recombinant human insulin — this is also factually correct. …
- AP EAPCET 2025Set ap-2025-05-19-AN1 markMCQQ.Which of the following human proteins is used to treat emphysema ? (A) Alpha - 1 antitrypsin (B) Alpha - interferon (C) Alpha - lactalbumin (D) Adenosine deaminase
›Reveal solutionSolution
This tests recall of therapeutic recombinant proteins in biotechnology. The answer is (A) Alpha-1 antitrypsin.
Concept and Intuition
Alpha-1 antitrypsin (AAT) is a protease inhibitor normally secreted by the liver that protects the delicate elastic tissue of the lungs from being broken down by neutrophil elastase. When a person has a genetic deficiency of AAT, elastase goes unchecked and progressively destroys lung alveolar walls, causing early-onset emphysema. Biotechnological production of AAT (e.g., recombinant human AAT, historically produced in transgenic sheep or through cell culture) allows replacement therapy for patients with this deficiency.
Step-by-Step Solution
- Alpha-interferon — used as an antiviral/anticancer agent (e.g., hepatitis, certain cancers), not for emphysema.
- Alpha-lactalbumin — a milk whey protein, of nutritional/biochemical interest, not a therapeutic for emphysema.
- Adenosine deaminase — its deficiency causes SCID (severe combined immunodeficiency); ADA-gene therapy addresses that condition, not emphysema. …
- AP EAPCET 2024Set ap-2024-05-17-FN1 markMCQQ.The first transgenic cow Rosie milk is enriched with (A) Alpha lactalbumin (B) Dystrophin (C) Oxytocin (D) Human chorionic Gonadotropin
›Reveal solutionSolution
This tests a well-known biotechnology fact: Rosie, the first transgenic cow, produced milk fortified with human alpha-lactalbumin.
Concept and Intuition
Transgenic animals carry a foreign gene deliberately introduced into their genome, often to make them produce a useful protein in a body fluid such as milk ("biopharming" / molecular pharming). Rosie is the textbook example cited in NCERT biotechnology chapters: she was engineered to produce milk containing higher amounts of human alpha-lactalbumin, a whey protein that improves the nutritional balance of milk for human babies compared to natural cow's milk.
Step-by-Step Solution
- Recall the specific named example "Rosie" from biotechnology applications in the NCERT syllabus.
- Recall the associated protein: alpha-lactalbumin, chosen because it makes cow milk more similar in composition to human milk. …
- AP EAPCET 2021Set ap-2021-09-07-FN1 markMCQQ.Consider the following statements about therapeutic drugs. Which of the statements given below are correct?(i) The recombinant DNA technology is used for production of therapeutic drugs which are safe and effective(ii) It avoids unwanted immunological responses, commonly observed with similar products isolated from non-human sources(iii) About thirty recombinant therapeutics have been approved for human use in the world including India (A)(i) &(ii) only (B)(i) &(iii) only (C)(ii) &(iii) only (D) (i),(ii) & (iii)
›Reveal solutionSolution
All three statements about recombinant therapeutic drugs are correct: they are safe and effective, avoid immune reactions from non-human sources, and about thirty such drugs are approved globally including in India.
The question tests your understanding of recombinant DNA technology in medicine. The key idea is that by inserting human genes into bacteria or yeast, we can produce human proteins (like insulin, growth hormone, or clotting factors) that are identical to our own. This avoids the problem of using animal-derived products, which can trigger allergic or immune responses because they are slightly different from human proteins. The number of approved recombinant therapeutics is a factual point, but it's widely cited in textbooks as around thirty.
Let's examine each statement:
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Statement (i): "The recombinant DNA technology is used for production of therapeutic drugs which are safe and effective."
This is true. Recombinant drugs are produced in controlled systems (e.g., E. coli or yeast) and are highly purified. Because they are identical to human proteins, they are safer than older animal-derived products (e.g., pig insulin) and are clinically effective. Examples include human insulin (Humulin) and erythropoietin.
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Statement (ii): "It avoids unwanted immunological responses, commonly observed with similar products isolated from non-human sources."
This is also true. Before recombinant technology, insulin was extracted from pigs or cows. Many patients developed antibodies against these animal insulins because they differ slightly in amino acid sequence. Recombinant human insulin is identical to the human hormone, so it rarely triggers an immune response. The same applies to human growth hormone and factor VIII for hemophilia. …
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