Recombinant DNA Technology & Genetically Modified Organisms (GMOs)
Genetic Engineering: A gene manipulation technology that alters the genetic constitution of an organism by introducing, removing, or modifying specific DNA sequences to produce desirable traits.
Recombinant DNA Technology: Combines DNA molecules from two different species to create a transgenic organism or produce useful biomolecules (e.g., human insulin production).
Key Tools:
Restriction Enzymes: Molecular scissors that cut DNA at specific nucleotide recognition sequences, creating "sticky ends".
DNA Ligase: Molecular glue that joins the target human gene fragment with plasmid DNA at complementary sticky ends.
Vector (Plasmid): Small, circular double-stranded DNA from bacteria used to transfer foreign target genes into host organisms.
Steps in Human Insulin Production:
Isolate the human insulin gene and target bacterial plasmid DNA.
Cut both human DNA and plasmid DNA using the same restriction enzyme.
Join the insulin gene with the linearized plasmid using DNA ligase to form recombinant plasmid DNA.
Insert recombinant plasmid into host Escherichia coli bacterial cells (Transformation).
Screen and clone transgenic bacteria in industrial fermenters to produce human insulin protein at commercial scale.
Genetically Modified Organisms (GMOs) & Genetically Modified Food (GMF): Organisms whose genomes have been artificially modified using genetic engineering.
Examples: Golden Rice (engineered with beta-carotene genes to treat Vitamin A deficiency), Bt Corn (resistant to corn borer insect pests), Roundup Ready Soybeans (herbicide-resistant).
13.2 Biotechnology
Applications, Forensics, and Bioethics
DNA Profiling (DNA Fingerprinting): Technique used to identify individuals based on unique repeating non-coding DNA sequences (Short Tandem Repeats, STRs).
Steps: DNA extraction $\rightarrow$ Polymerase Chain Reaction (PCR) amplification $\rightarrow$ Cutting with restriction enzymes $\rightarrow$ Gel electrophoresis separation $\rightarrow$ Southern blot / Radioactive probe visualization.
Applications: Solving crime scenes in forensic investigations, paternity testing, identifying human remains, confirming biological kinship.
Gene Therapy: Treatment or prevention of genetic disorders by inserting normal, functional genes into host cells to replace or repair mutated, non-functional genes (e.g., treating Severe Combined Immunodeficiency, SCID, and Cystic Fibrosis).
Bioremediation: Use of biological agents (microorganisms, plants, or fungi) to degrade, neutralize, or remove environmental pollutants from contaminated soil or water (e.g., using Pseudomonas bacteria to break down oceanic oil spills).
Bioethics & Safety Issues:
Ethical Concerns: Unintended allergen transfers in GMFs, loss of agricultural biodiversity through crop monoculture, gene flow to wild weeds creating "superweeds", animal welfare issues, genetic discrimination in insurance/employment based on DNA profiles.