12.3 Bacteria, Viruses, and Biotechnology (p.405-411)

SBI3U1-02Jackie Do

Tina Giang

Foundation of Biotechnology• Biotechnology can be defined as manipulating

living organisms or their components to provide products or to serve useful purposes

• Biotechnology was used since the beginning of a record history. Recorded history is part of human history

that has been written down or recorded by the use of language

• Biotechnology is any commercial application of living organisms or their products that involves the direct manipulation of their DNA molecules

Figure 12.19An overview of genetic engineering. Bacteria play a central role in biotechnology.

Genetic Engineering• Biologists can now alter the DNA of an organism

directlyThe technique used to make these alterations

is known as genetic engineering.• An example of Biotechnology:

In order to take one gene from one organism and insert it into another organism, you need to:1. Cut out a section of DNA from the first

organism2. Combine this DNA with the DNA from

another organism3. Insert the combined DNA into another

organism Bacteria and viruses are often used to

perform these 3 steps

Bacteria and Recombinant DNA• The process of genetic engineering starts with cutting out a

section of DNA from the cell of an organism. In order to do this, scientists use restriction enzymes in which they act as chemical scissors.

• There are many different types of restriction enzymes and each type recognizes specific nucleotide sequence in DNA. As soon as an enzyme recognizes its sequence, it cuts the DNA at that point.

• Figure 12.20: Recombination of genes. This process happens in-vitro, outside the cell. Restriction enzymes cut both the plasmid DNA and the DNA to be inserted in the same nucleotide sequence on their DNA.

Bacteria and Recombinant DNA (cont.)• Bacteria contains plasmids. They are useful in

biotechnology because they provide a site for genetic recombination. Plasmids are removed from the bacteria and cut with the same restriction enzyme used to cut the DNA from the animal cell. As a result of this, the restriction enzyme creates `sticky ends`. These ends are complementary so the animal DNA `fits` into the plasmid.

• The process of inserting one set of genetic material into another is called gene splicing. The plasmid is now considered to be recombinant DNA because it has DNA from two organisms. This plasmid is also known as a cloning vector.

Application of Genetic Cloning• Once you have large amounts of recombinant

DNA through genetic cloning, this DNA can be used in different ways such as completing basic research on the DNA itself.

• For example, you can find biopharmaceuticals in the application of genetic cloning.

Viruses and Genetic Engineering

• Viruses can be used as cloning vectors similar to bacterial plasmids. Viruses are used instead of plasmids if the DNA strand to be manipulated is quite long. Using a virus as a cloning vector takes advantage of a virus` DNA, which is the goal of any cloning vector.

• Another possible use of viruses in biotechnology is in gene therapy. Figure 12.22: Genetically engineered viruses can be used to insert a normal allele into a human chromosome.

chromosomes