BC08 — Biotechnology & Its Applications

📖 BC08 · CDS General Knowledge — Biology CDS Level

Biotechnology applies biological systems to create products and solve problems. CDS tests the basics — what restriction enzymes do, what Bt cotton is, how recombinant insulin is made. These are low-yield but easy-scoring questions if you prepare the key facts.

📌 CDS Focus: Restriction enzymes = "molecular scissors" that cut DNA at specific sequences; plasmids = vectors (carry foreign DNA into host cell); Bt cotton = gene from Bacillus thuringiensis inserted — makes plant resistant to bollworm pest; Humulin = human insulin produced by recombinant bacteria (E. coli); gene therapy = correcting genetic defects by inserting normal genes.

1. Tools of Biotechnology

ToolWhat it doesAnalogy Restriction enzymesCut DNA at specific palindromic sequences ("recognition sites"); produce sticky ends for joining"Molecular scissors" — cut at a very specific location DNA ligaseJoins (seals) cut DNA fragments together; creates recombinant DNA"Molecular glue / stapler" Plasmids (vectors)Small circular DNA in bacteria; used to carry foreign gene into host cell"Molecular trucks/vehicles" PCRPolymerase Chain Reaction; amplifies (makes many copies of) a small DNA segment rapidly"Molecular photocopier" Gel electrophoresisSeparates DNA fragments by size using electric current; smaller fragments travel farther"Molecular sieve"

2. Key Applications

🍁 Agricultural Biotechnology

Bt cotton: Gene from Bacillus thuringiensis (Bt) inserted — produces Cry protein, toxic to cotton bollworm. First GM crop approved in India (2002).
Golden Rice: Beta-carotene (Vitamin A precursor) gene inserted; addresses Vitamin A deficiency in developing nations.
Bt brinjal: Pest-resistant brinjal; controversial in India.
GM crops = Genetically Modified crops; aim: higher yield, pest resistance, drought tolerance

💊 Medical Biotechnology

Humulin (recombinant insulin): Human insulin gene inserted into E. coli bacteria; bacteria then produce insulin. First recombinant DNA drug (1982).
Gene therapy: Inserting a normal copy of a defective gene to cure genetic diseases (e.g., SCID).
Vaccines: Recombinant vaccines (Hepatitis B vaccine made using yeast); subunit vaccines.
Monoclonal antibodies: Used for diagnosis and targeted cancer therapy.

📝 CDS PYQs — Biotechnology

Q1. Bt cotton is resistant to pest attack because: CDS PYQ

(a) It produces a toxin from an inserted bacterial gene(b) It has thicker cell walls(c) It produces insecticides sprayed externally(d) It has no cellulose

✔ Answer: (a) Toxin from inserted bacterial gene

Bt cotton contains a gene from Bacillus thuringiensis (a soil bacterium) that encodes a Cry protein (crystal protein). When ingested by cotton bollworm larvae, the Cry protein is activated in the alkaline insect gut, binds to gut cells, and kills the insect. Human and mammalian guts are acidic, so the protein is harmless to humans. First approved GM crop in India (2002) — approved by GEAC (Genetic Engineering Appraisal Committee).

Q2. Restriction enzymes are used in genetic engineering as: CDS PYQ

(a) Molecular glue to join DNA fragments(b) Molecular scissors to cut DNA at specific sites(c) Carriers of foreign DNA(d) Primers for DNA replication

✔ Answer: (b) Molecular scissors

Restriction endonucleases (restriction enzymes) recognise specific palindromic DNA sequences and cut both strands — like molecular scissors. They create "sticky ends" that allow complementary DNA fragments to be joined. First isolated from bacteria (they evolved to cut viral DNA). Example: EcoRI cuts at sequence G↓AATTC. DNA ligase (glue) then joins the cut ends together to create recombinant DNA.

🧠 Quick Memory Chart — BC08

📊 Biotech Tools

Restriction enzyme: molecular scissors
DNA ligase: molecular glue
Plasmid: vector (molecular truck)
PCR: amplifies DNA (molecular copier)
Gel electrophoresis: separates by size

🍁 Agriculture

Bt cotton: gene from Bacillus thuringiensis
Cry protein: kills bollworm larvae
Approved in India: 2002
Golden Rice: beta-carotene (Vit A)
GM = Genetically Modified

💊 Medicine

Humulin: insulin from E. coli (1982)
Gene therapy: inserts normal gene
SCID: first gene therapy target
Hep B vaccine: recombinant (yeast)
Monoclonal antibodies: targeted therapy

📝 Practice Exercise

E1. The first genetically engineered drug used in humans was:

(a) Penicillin(b) Humulin (recombinant insulin)(c) Aspirin(d) Paracetamol

E2. PCR (Polymerase Chain Reaction) is used to:

(a) Cut DNA at specific sites(b) Join DNA fragments(c) Make millions of copies of a DNA segment(d) Separate proteins by size

Answers:
E1 → (b) Humulin [approved by FDA in 1982; produced using recombinant E. coli] | E2 → (c) Make millions of copies [PCR uses repeated heating-cooling cycles with DNA polymerase to exponentially amplify target DNA]

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