Biotechnology

Biotechnology applies biological systems and organisms to solve practical problems — particularly in medicine, agriculture, and industry. The PMDC MDCAT 2026 syllabus focuses on biotechnology in health care: recombinant DNA technology, production of insulin and human growth hormone, vaccines, and gene therapy. Expect 1-2 MCQs per paper.

PMC Table of Specifications. The PMDC syllabus restricts this chapter to Biotechnology and Health Care — recombinant DNA, genetic engineering, pharmaceutical applications, gene therapy, and DNA fingerprinting.

Biotechnology and Health Care

Biotechnology is the use of living organisms (or their parts and products) to make commercially useful goods or services. Genetic engineering is the deliberate modification of an organism's DNA to give it new traits.

Key tools

Restriction endonucleases: Enzymes that cut DNA at specific recognition sequences (e.g., EcoRI cuts GAATTC). Often produce sticky ends that anneal to complementary fragments.
DNA ligase: Joins two DNA fragments together by forming a phosphodiester bond.
Vector: A DNA molecule (commonly a bacterial plasmid or a viral genome) used to deliver a foreign gene into a host cell.
Recombinant DNA: A DNA molecule formed by joining DNA fragments from two different sources.
PCR (polymerase chain reaction): In-vitro amplification of a DNA segment using Taq polymerase, primers, and thermal cycling. Invented by Kary Mullis (Nobel 1993).
Gel electrophoresis: Separation of DNA fragments by size in an agarose gel under an electric field. Smaller fragments travel faster.

Recombinant insulin production (Humulin, 1982)

The first genetically engineered human therapeutic.

Human insulin gene is isolated and cut with a restriction enzyme.
A bacterial plasmid is cut with the same enzyme to give matching sticky ends.
DNA ligase joins the insulin gene into the plasmid, forming recombinant DNA.
The plasmid is inserted into E. coli, which is grown in fermenters.
Bacteria express insulin, which is purified for diabetic patients.

Recombinant insulin replaced the older porcine and bovine insulin, which often caused allergic reactions.

Recombinant vaccines

The hepatitis B vaccine is produced by inserting the HBsAg (hepatitis B surface antigen) gene into yeast. The yeast secretes the antigen, which is purified and used as a safe, non-infectious vaccine. Other recombinant products: human growth hormone (somatotropin), erythropoietin, factor VIII (haemophilia), interferons.

Gene therapy

Insertion of a functional gene into a patient's cells to treat a genetic disorder. Somatic gene therapy targets body cells (not heritable). Germline gene therapy targets gametes/embryos (heritable; banned in humans). Most often delivered by retroviral or adenoviral vectors. Pioneered for ADA-SCID ("bubble boy" disease) in 1990.

DNA fingerprinting (DNA profiling)

Developed by Sir Alec Jeffreys (1984). Uses variable number tandem repeats (VNTRs) or short tandem repeats (STRs) that differ between individuals. Each person (except identical twins) has a unique pattern. Applications: paternity testing, forensic identification, mass-disaster victim ID.

Stem cell therapy

Stem cells are unspecialised cells capable of self-renewal and differentiation. Sources: embryonic stem cells, adult/somatic stem cells, induced pluripotent stem cells (iPSCs). Used or studied for leukaemia (bone marrow transplant), Parkinson's disease, spinal cord injury, type-1 diabetes.

Diagnostic biotechnology

ELISA detects antigens or antibodies (HIV screening, COVID-19 antibody testing). PCR detects pathogen DNA/RNA at very low copy numbers (TB, HCV, COVID-19). Monoclonal antibodies produced by hybridoma technology are used in pregnancy tests, blood-typing, and targeted cancer therapy (e.g., trastuzumab).

Applications — quick list

Recombinant insulin, growth hormone, factor VIII, erythropoietin, interferons.
Recombinant vaccines (hepatitis B, HPV).
Gene therapy for ADA-SCID, cystic fibrosis trials, sickle-cell disease.
DNA fingerprinting in forensics & paternity.
PCR & ELISA in disease diagnosis.
Tissue engineering & stem-cell transplants.
Pharmacogenomics — personalised medicine based on genotype.

Common trap. A vector in biotechnology is the carrier DNA (plasmid or virus) — not the disease-transmitting mosquito of parasitology. Examiners often write a question about plasmids and offer "mosquito" as a distractor.

Memory aid. "Cut, Copy, Paste, Express" — cut the gene with a restriction enzyme, copy it with PCR, paste it into a plasmid with ligase, and express it in a host cell. That's the entire recombinant-DNA workflow.

Diseases targeted by biotech therapies

Diabetes mellitus — recombinant insulin.
Dwarfism (pituitary) — recombinant human growth hormone.
Haemophilia A — recombinant clotting factor VIII.
Anaemia (renal failure) — recombinant erythropoietin.
Hepatitis B / cervical cancer (HPV) — recombinant subunit vaccines.
ADA-SCID, sickle-cell disease, beta-thalassaemia — gene therapy.

Worked MCQs

Five MCQs that capture the high-yield testing patterns for this chapter.

Q1. Which enzyme is used to cut DNA at specific nucleotide sequences?

DNA ligase
Restriction endonuclease
Reverse transcriptase
DNA polymerase

Restriction endonucleases (e.g., EcoRI, HindIII) recognise palindromic sequences and cleave both strands, often producing sticky ends. DNA ligase joins fragments back together.

Q2. The first commercially produced recombinant human protein was:

Growth hormone
Factor VIII
Insulin
Erythropoietin

Recombinant human insulin (Humulin) was approved in 1982 by the FDA — the first commercial product of recombinant DNA technology in medicine.

Q3. Which technique amplifies a small DNA sample into millions of copies?

Gel electrophoresis
ELISA
Polymerase chain reaction (PCR)
Western blotting

PCR uses thermostable Taq polymerase, primers, and cycles of denaturation, annealing, and extension to exponentially amplify a target DNA segment. Invented by Kary Mullis in 1983.

Q4. Bacterial plasmids are most often used in genetic engineering as:

Antibiotic substitutes
Restriction enzymes
Vectors carrying foreign genes
Replacements for chromosomal DNA

Plasmids are small, circular, self-replicating DNA molecules that exist independently of the bacterial chromosome. They can be cut, joined with foreign DNA, and reintroduced into bacteria — making them ideal cloning vectors.

Q5. Gene therapy for severe combined immunodeficiency (SCID) most commonly uses which type of vector?

Bacterial plasmid
Retrovirus
Bacteriophage
Yeast artificial chromosome

Retroviruses (and adeno-associated viruses) are the standard gene-therapy vectors for human cells because they integrate the corrective gene stably into the host genome. The first successful human gene therapy (1990) treated ADA-SCID using a retroviral vector.

Quick Recap

Biotechnology = use of organisms or their products for human benefit.
Tools: restriction enzymes (cut), ligase (join), plasmids (vectors), PCR (amplify), gel electrophoresis (separate).
Recombinant insulin (1982) was the first biotech drug; produced in E. coli.
Recombinant vaccines: hepatitis B, HPV.
Gene therapy uses viral vectors to deliver corrective genes; somatic only is approved.
DNA fingerprinting (Jeffreys, 1984) uses VNTRs/STRs for forensic and paternity testing.
ELISA + PCR = backbone of modern infectious-disease diagnosis.

Test yourself. Take a timed practice test or browse topic-wise MCQs to lock these concepts in.