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Introduction to
"Biotechnology"
Biotechnology generally refers to the use of microorganisms to produce certain
chemical compounds. Long before the term "biotechnology" was coined for the
process of using living organisms to produce improved commodities, people were
utilizing living micro-organisms to produce valuable products. A list of early
biotechnology applications follows below.
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Proving bread with leaven prehistoric
period
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Fermentation of juices to alcoholic
beverages prehistoric period
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Knowledge of vinegar formation from
fermented juices prehistoric period
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Cultivation of vine before 2000 BC
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Manufacture of beer in Babylonia and
Egypt 3rd century BC
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Wine growing promoted by Roman Emperor
Marcus Aurelius Probus 3rd century AD
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Production of spirits of wine
(ethanol) 1150
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Vinegar manufacturing industry 14th
century
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Discovery of the fermentation
properties of yeast by Erxleben 1818
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Description of lactic acid
fermentation by Pasteur 1857
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Detection of fermentation enzymes in
yeast by Buchner 1897
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Discovery of penicillin by Fleming
1928/29
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Discovery of many other antibiotics
from about 1945
Since then "biotechnology" has rapidly
progressed and expanded. In the mid-forties, scale-up and commercial production
of antibiotics such as penicillin occurred. The techniques used were (a)
isolation of an organism producing the chemical of interest using
screening/selection procedures, and (b) improvement of production yields via
mutagenesis of the organism or optimization of media and fermentation
conditions. This type of "antique" biotechnology is limited to chemicals
produced in nature. It is also limited by its trial-and-error approach, and
requires a lengthy timeframe (years or even decades) for yield improvement.
About two decades ago, biotechnology became much more of a science (rather than
an art). Regions of DNA (called genes) were found to contain information that
would lead to synthesis of specific proteins (which are strings of amino acids).
Each of these proteins have their own identity and function; many catalyze
(facilitate) chemical reactions, and others are structural components of
entities in cells. If one now is able to express a natural gene in simple
bacteria such as Escherichia coli (E. coli), a bacterium living in intestines
that has become the model organism for much of biotechnology, one can have this
bacterium make a lot of the protein coded for by the gene, regardless its
source. The techniques used for this development include (a) isolation of the
gene coding for a protein of interest, (b) cloning of this gene into an
appropriate production host, and (c) improving expression by using better
promoters, tighter regulation, etc.; together these techniques are known as
recombinant DNA techniques. These will be discussed at some length in the
course.
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The commercial implications are that
a large number of proteins, existing only in tiny quantities in nature, can now
be mass-produced if needed. Also, the yields of (bio)chemicals to be produced
can be increased much faster than was possible with classical fermentation.
These modern biotechnology techniques started with the expression of human genes
such as that coding for insulin, but have since been extended to mammalian,
microbial, and plant genes. Also, the spectrum of "bioreactors" (organisms used
for production) recently has been broadened to include a variety of animals and
plants. As we will see, perceived needs and marketability, the researchers'
imagination, ethics, and governmental regulations essentially are the major
factors in setting the stage and boundaries for developments in biotechnology.
About a decade ago, "protein engineering" became possible as an offshoot of the
recombinant DNA technology. Protein engineering differs from "classical"
biotechnology in that it is concerned with producing new (man-made) proteins
which have been modified or improved in some way. The techniques involved in
protein engineering are more complicated than before, and involve (a) various
types of mutagenesis (to cause changes in specific locations or regions of a
gene to produce a new gene product), (b) expression of the new gene to form a
stable protein, (c) characterization of the structure and function of the
protein produced, and (d) selection of new locations or regions to modify as a
result of this characterization.
In the mid-eighties and early-nineties, it has become possible to transform
(genetically modify) plants and animals that are important for food production.
"Transgenic" animals and plants, including cows, sheep, tomatoes, tobacco,
potato, and cotton have now been obtained. Genes introduced may make the
organism more resistant to disease, may influence the rate of fruit ripening, or
may increase productivity. As this approach leads to release of genetically
altered organisms into the environment, this part of biotechnology is quite
strictly regulated at government levels. Recent advances in this area of modern
biotechnology are numerous, and some will be highlighted in this course.
Below is an overview of recombinant DNA based biotechnology:
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1953 Double helix structure of DNA is
first described by Watson and Crick.
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1973 Cohen and Boyer develop genetic
engineering techniques to "cut and paste" DNA and to amplify the new DNA in
bacteria.
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1977 The first human protein (somatostatin)
is produced in a bacterium (E. coli).
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1982 The first recombinant protein
(human insulin) appears on the market.
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1983 Polymerase chain reaction (PCR)
technique conceived.
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1990 Launch of the Human Genome
Project (HGP), an international effort to sequence the human genome.
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1995 The first genome sequence of an
organism (Haemophilus influenzae) is determined.
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2000 A first draft of the human genome
sequence is completed.
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2005 Over 40 million gene sequences
are in GenBank, and genome sequences of hundreds of prokaryotes and dozens
of eukaryotes are finished or in draft stage.
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