Biology · Biotechnology and Its Applications · NEET
Genetically engineered insulin, sold as Humulin, is human insulin made by bacteria (E. coli) using recombinant DNA technology, not taken from any human body. Before this, insulin was extracted from the pancreas of slaughtered cattle and pigs, which sometimes caused allergy in patients. Memory hook: "Humulin = HUMan insulin from a microbe" — same human protein, safe, and made in unlimited amounts.
Eli Lilly (1983) inserted human insulin A- and B-chain genes into E. coli plasmids; the chains were made separately, extracted, and joined by disulphide bonds to form mature human insulin (Humulin).
Your doubts, answered
Is genetically engineered insulin the same as the insulin our body makes?
Yes. The bacterium is given the human genes for insulin chains, so the protein it makes has the exact same amino acid sequence as human insulin. That is why it is called 'human insulin' even though a microbe produced it. It works better and is safer than insulin taken from other animals.
Why was animal insulin (from cattle and pigs) replaced?
Insulin from other animals is a slightly different (foreign) protein. NCERT states that animal-source insulin caused some patients to develop allergy or other reactions to the foreign protein. Genetically engineered human insulin removes this problem because it matches our own insulin exactly.
Does E. coli make human insulin on its own?
No. E. coli cannot make insulin naturally. Scientists insert the human insulin gene sequences into the plasmid (a small circular DNA) of E. coli. Only then does the bacterium read those genes and produce the insulin chains. The bacterium is just a factory.
Which company first produced genetically engineered insulin?
Eli Lilly, an American company, in 1983. They prepared two DNA sequences for the A and B chains of human insulin, put them into E. coli plasmids to make the chains separately, then combined the chains by forming disulphide bonds. This is a favourite NEET fact (asked directly in NEET 2025).
Why can insulin not be given as a tablet (orally)?
Insulin is a protein (peptide hormone). If swallowed, the digestive enzymes and stomach acid would break it down into amino acids before it could act, so it would not work. That is why insulin is given by injection, and this 'why' reasoning is a common NEET-style question.
⚠️ The NEET trap ✗ Genetically engineered insulin is extracted from the human pancreas. ✓ It is human insulin synthesised by E. coli (a bacterium) using recombinant DNA technology — not extracted from any pancreas. The old, replaced method extracted insulin from the pancreas of cattle and pigs. 🧠 'Genetically engineered' means MADE by a microbe, not EXTRACTED from an organ. If an option says extracted from human/animal pancreas for Humulin, reject it.
Real NEET questions
NEET 2025
Which of the following genetically engineered organisms was used by Eli Lilly to prepare human insulin?
A · Virus
B · Phage
C · Bacterium ✓
D · Yeast
Solution: In 1983 Eli Lilly introduced the DNA sequences coding for the A and B chains of human insulin into plasmids of E. coli (a bacterium) to produce the insulin chains. So the genetically engineered organism was a bacterium.
NEET 2019
Which of the following features of genetic code does allow bacteria to produce human insulin by recombinant DNA technology?
A · Genetic code is not ambiguous
B · Genetic code is redundant
C · Genetic code is nearly universal ✓
D · Genetic code is specific
Solution: Because the genetic code is nearly universal, the same codons specify the same amino acids in humans and in bacteria. So a human insulin gene is read correctly by E. coli, letting the bacterium make authentic human insulin.
NEET 2016
Which of the following statements is not correct?
A · The functional insulin has A and B chains linked together by hydrogen bonds ✓
B · Genetically engineered insulin is produced in E. coli
C · In man insulin is synthesised as a proinsulin
D · The proinsulin has an extra peptide called C-peptide
Solution: The A and B chains of insulin are linked by disulphide bridges, not hydrogen bonds, so this statement is incorrect. The other three are true: genetically engineered insulin is made in E. coli, insulin is first made as proinsulin, and proinsulin has an extra C-peptide.
Solved Biotechnology and Its Applications NEET PYQs
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Humulin is the commercial name for genetically engineered human insulin — human insulin produced by E. coli bacteria using recombinant DNA technology and used to treat diabetes.
Who made the first genetically engineered insulin and when?
Eli Lilly, an American company, in 1983.
Which organism is used to produce genetically engineered insulin?
E. coli, a bacterium. Human insulin gene sequences are inserted into its plasmids.
Why is genetically engineered insulin better than animal insulin?
It is identical to human insulin, so it does not cause the allergy or immune reactions that foreign animal insulin sometimes did, and it can be made in large amounts easily.
Is genetically engineered insulin given as a tablet?
No. Insulin is a protein and would be digested in the stomach, so it is given by injection.
