Introduction

Biotechnology is the set of technologies that use living cells and/or biological molecules to make useful products for the benefit of mankind. The word combines bio (biological systems or processes) and technology (methods, systems and devices used to make useful products).

Examples:
- Making curd (dahi) from milk using Lactobacillus bacteria
- Production of bread, cheese, wine and beer by fermentation
- Production of human insulin using rDNA technology in _E. coli_
- Development of Bt cotton for insect resistance

Ancient biotechnology and modern biotechnology differ mainly in their basis and level of control.

Ancient biotechnology:
- Began long ago, around the Paleolithic era
- Based on traditional practices and trial and error
- Included domestication, selective breeding, and fermentation
- Examples: cultivation of wheat and barley, domestication of sheep, goat and cattle, making bread, cheese, wine, beer, curd
- People used the processes without knowing the microbial or biochemical basis

Modern biotechnology:
- Developed with advances in cell biology, molecular biology, genetics and biochemistry
- Based mainly on recombinant DNA (rDNA) technology
- Uses controlled manipulation of genes and biological systems
- More precise, efficient and targeted
- Examples: production of human insulin in bacteria, gene therapy, Bt cotton, Golden Rice, edible vaccines

Thus, ancient biotechnology involved natural processes used traditionally, while modern biotechnology uses scientific and genetic methods to obtain improved and novel products.

Biopharmaceutical production is an important application of biotechnology in medicine.

- rDNA technology is used to develop biopharmaceuticals with therapeutic value.
- Useful protein molecules are expressed in heterologous systems such as microorganisms and transgenic plants.
- A common example is human insulin, produced in _E. coli_ and _Saccharomyces cerevisiae_ for the treatment of diabetes.
- Human growth hormone is another example produced using microbial host systems.
- Some therapeutic proteins are also expressed in the milk of transgenic sheep and goats.
- The FDA has approved production of a blood anti-coagulant in milk of transgenic goats for human use.
- Biotechnology is also being used to develop drugs against hepatitis, cancer and heart diseases.

Gene therapy is a biotechnology-based treatment in which a required gene is delivered into a patient's cell to replace the function of a defective gene.

Applications:
- Useful for diseases caused by gene defects such as cystic fibrosis, thalassemia and Parkinson's disease
- The first attempt was by Martin Cline in 1980 for β-thalassemia
- The first successful report was in 1990 when Ashanthi De Silva was treated for Adenosine Deaminase deficiency (ADA-SCID)
- Neovasculgen was approved by Russia in 2011 for peripheral artery disease
- Gendicine was the first commercial gene therapy product approved for cancer treatment in China in 2003

So, gene therapy is used to treat inherited and some other genetic disorders by correcting the faulty gene function.

Abiotic stress resistance means resistance to non-living environmental stresses such as cold, salt, drought and herbicides.

Examples from the chapter:
- Chilling resistance was introduced into tobacco by introducing the gene for glycerol-1-phosphate acyl-transferase from _Arabidopsis_.
- Roundup-ready soybeans were developed so that they are unaffected by glyphosate herbicide.
- Such plants can survive stressful conditions better and can also help in selective weed control.

These biotechnological approaches improve crop survival and productivity under unfavorable conditions.