12.3 Bacteria, Viruses, and Biotechnology (p.405-411) SBI3U1-02 ...


14 déc. 2012 (il y a 9 années et 1 mois)

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12.3 Bacteria, Viruses, and


Jackie Do


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

Recorded history is part of human history that has
been written down or recorded by the use of

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

Figure 12.19

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

Genetic Engineering

Biologists can now alter the DNA of an organism directly

The 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:

Cut out a section of DNA from the first organism

Combine this DNA with the DNA from another

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

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

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