2. Biotechnology

Genetic engineering is the manipulating and transferring genes from one organism to another to create a new DNA called recombinant DNA (rDNA).
Paul Berg introduced a gene of SV-\(40\) into a bacteria with the help of lambda phage. He is thus considered the "Father of genetic engineering".
 
Tools in Genetic Engineering:
 
1. Plasmids: Small circular extra-chromosomal DNA in bacteria that replicate independently and act as vectors in genetic engineering.
2. Restriction enzymes: Molecular scissors that cut DNA at specific palindromic restriction sites.
3. DNA ligase: Molecular glue that joins or seals DNA fragments to form recombinant DNA.
 
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Plasmid, Restriction enzymes and DNA ligase action (clockwise)
 
Process of genetic engineering:
 
1. Recombinant DNA formation: Desired DNA fragments are cut with restriction enzymes and joined with vectors (plasmids) using DNA ligase.
2. Gene cloning: The recombinant DNA is introduced into a host cell, where it replicates to produce many identical DNA copies. The newly formed DNA having integrated fragments of the antibiotic-resistant gene is known as recombinant DNA.
3. Gene transfer: The cloned gene is expressed in the host organism to produce useful products like enzymes, hormones, or vaccines.
 
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Steps involved in genetic engineering 
 
Cloning of animals - Dolly the Sheep:
 
1. Dolly, the first cloned mammal, was created in \(1996\) by Ian Wilmut using somatic cell nuclear transfer (SCNT) from a Finn Dorset sheep cell.
2. The nucleus from a somatic cell was inserted into an enucleated egg of a Scottish Blackface ewe and implanted into its uterus.
3. Dolly was genetically identical to the Finn Dorset sheep and demonstrated the possibility of cloning animals with desirable traits.
 
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Process of cloning Dolly through Somatic Cell Nuclear Transfer (SCNT)
 
Biotechnology in medicine:
 
Biotechnology uses living organisms or their components to develop products for human welfare, and through genetic engineering it produces recombinant therapeutic proteins such as insulin, human growth hormone, blood clotting factors, and vaccines for treating diseases.
 
Genetically engineered insulin:
  • Insulin, produced by β-cells of the pancreas, is first formed as proinsulin (A, B, and C chains), where the C-peptide is removed to produce active insulin.
  • In 1983, Eli Lilly produced recombinant insulin (Humulin) by inserting A and B chain genes into E. coli and later joining them with disulfide bonds.
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Synthesis of insulin from proinsulin
 
Gene therapy:
  • Gene therapy treats genetic disorders by replacing a faulty gene with a normal functional gene using recombinant DNA technology.
  • It is of two types: germline gene therapy (gene replacement in germ cells) and somatic gene therapy (gene replacement in body cells).
  • Currently, gene therapy is mainly applied to somatic cells to treat diseases such as SCID, Duchenne muscular dystrophy, and cystic fibrosis.
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Gene therapy
 
Stem cells:
  • Stem cells are undifferentiated cells with potency, capable of self-renewal and differentiation into specialised cells.
  • Two types: Embryonic stem cells (from blastocyst, can form any body cell) and Somatic/adult stem cells (found in bone marrow, umbilical cord, etc.).
  • Stem cell therapy uses stem cells to replace damaged tissues or cells in diseases such as Parkinson’s and Alzheimer’s.
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Embryonic stem cells, Adult stem cells, and stem cell therapy for leukemia
 
DNA Fingerprinting:
  • DNA fingerprinting, developed by Alec Jeffreys, identifies individuals by analyzing unique DNA sequences.
  • It uses VNTRs (Variable Number of Tandem Repeats) found in the\(\ 1%\) variable satellite DNA of the human genome.
  • Applications include forensic identification, paternity testing, diagnosis of genetic disorders, and population genetic studies.
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Steps involved in DNA fingerprinting
 
Genetically modified organisms (GMO):
  1. Genetic modification uses recombinant DNA technology to insert a transgene, producing transgenic (GM) plants and animals with desirable traits.
  2. Transgenic plants show better nutrition, higher yield, and pest resistance (e.g., Golden Rice with β-carotene, Bt crops resistant to insects).
  3. Transgenic animals are developed to improve livestock quality and produce therapeutic proteins (e.g., transgenic sheep and salmon).
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Bt cotton, Golden rice, Transgenic zebra fish larva and Transgenic sheep
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