Principles of biotechnology
Biotechnology uses living organisms or their enzymes to make useful products. It rests on two core techniques: genetic engineering and bioprocess engineering.
What biotechnology means
Biotechnology is the use of live organisms, or enzymes taken from them, to make products and processes useful to humans. Making curd, bread or wine with microbes is old biotechnology. Today the word mostly means using genetically modified organisms to make products on a large scale. In vitro fertilisation, making a gene in the lab, developing a DNA vaccine and correcting a faulty gene are all part of it. The European Federation of Biotechnology defines it as joining natural science with organisms, cells, their parts and molecular analogues to give products and services.
The two core techniques
Genetic engineering makes the right cell; bioprocess engineering grows it in bulk.
Why genetic engineering, and why an origin of replication
Asexual reproduction keeps genetic information the same; sexual reproduction creates variation. Traditional hybridisation often carries unwanted genes along with the wanted one. Genetic engineering moves only the desired gene (or set of genes) into the target organism. But a piece of foreign (alien) DNA cannot multiply on its own in the progeny cells. It multiplies only if it is linked to a DNA sequence called the origin of replication (ori), where replication starts. Making many identical copies of a DNA in this way is called cloning.
The first recombinant DNA (Cohen and Boyer, 1972)
- 1A piece of DNA carrying an antibiotic resistance gene was cut out of a plasmid using restriction enzymes, the 'molecular scissors'.Restriction enzyme
- 2A native plasmid of Salmonella typhimurium was cut with the same kind of enzyme.A plasmid is a small, circular, self-replicating DNA outside the bacterial chromosome
- 3★The gene was joined to the plasmid by DNA ligase. This new circular DNA, made in vitro, is recombinant DNA.DNA ligase
- 4The recombinant DNA was put into Escherichia coli, a bacterium closely related to Salmonella.
- 5★It replicated using the host's DNA polymerase and made many copies: the cloning of the antibiotic resistance gene in E. coli.
★ key step
Three basic steps in genetically modifying an organism
The process of recombinant DNA technology, in order
Each box is a later topic in this chapter. Learn the order: it is a common 5-mark question.
Human insulin, the hepatitis B vaccine and many enzymes for Indian food and textile industries come from bioprocess engineering. Even curd and idli batter rely on microbes, the oldest form of biotechnology.
2 marks: “Name the two core techniques that made modern biotechnology possible. What does each involve?” Genetic engineering: altering DNA or RNA, introducing it into a host and changing the host's phenotype. Bioprocess engineering: keeping sterile conditions so only the desired microbe or cell grows in large quantities to make antibiotics, vaccines, enzymes.
3 marks: “How was the first recombinant DNA made? Why could the alien DNA multiply in E. coli?” Cohen and Boyer, 1972. Antibiotic resistance gene cut from a plasmid with restriction enzymes; joined to a native plasmid of Salmonella typhimurium by DNA ligase; put into E. coli. The plasmid had an origin of replication, so it replicated with the host's DNA polymerase: cloning.
5 marks: “List the steps of recombinant DNA technology in order. Explain any three, naming the tool used at each.” Isolate DNA; cut with restriction enzyme; isolate the fragment by gel electrophoresis; ligate into a vector with DNA ligase; transfer into a competent host; culture in a bioreactor; downstream processing. Explain three with their enzyme or tool.
Biotech stands on two legs: genetic engineering changes the gene, bioprocess engineering grows it big and sterile.