Download Biotechnology Cloning of a Gene Cloning a human gene

Cloning of a Gene
Biotechnology
Recombinant DNA Technology
• Cloning is the production of identical
copies through asexual means.
• Cloning occurs naturally in new plant
shoots, bacterial colonies, and identical
human twins.
• Gene cloning is the engineering and thus
production of many identical copies of a
genes
Cloning a human gene
• Recombinant DNA contains DNA from
two or more different sources.
– Recombinant DNA can be the recombination
of parents DNA to form a hybrid offspring
(you and I are an example of a hybrid)
• A plasmid can be used as a to insert
foreign DNA into a cell
– A plasmid is a small ring of DNA transmitted
between bacteria that live close to one
another
Cloning of a Gene
• Restriction enzymes “cut” the
recombinant DNA and the source DNA at
a specific sequence, leaving “sticky”
ends, that allow a portion of source DNA
to be inserted into the vector DNA.
• Bacterial cells take up recombinant
plasmids and clone the new DNA
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The Polymerase Chain Reaction
The Polymerase Chain Reaction
• The polymerase chain reaction (PCR)
produces many copies of a single gene or
piece of DNA.
• PCR requires DNA polymerase and a
supply of nucleotides for the new DNA
strands.
• PCR is a chain reaction because the
targeted DNA is repeatedly replicated as
long as the process continues.
Analyzing DNA Segments
• The entire genome of an individual can be
cut by restriction enzymes to yield
variable fragment lengths.
• Gel electrophoresis separates fragment
lengths and the use of probes results in a
pattern unique to the individual,
sometimes called a DNA fingerprint.
Cloning of a Gene
– A DNA fingerprint resembles that of one’s
parents because it is inherited.
• It’s possible to identify a person who has
committed a crime, identify a cancer gene,
or tell who is related to whom by
performing a DNA fingerprint.
• Since PCR can amplify the smallest
amount of DNA, a single sperm, or one
cell on a toothbrush, provides enough
DNA to be identified by comparison with
sample DNA.
Biotechnology Products
Transgenic Bacteria
• Today, bacteria, plants, and animals are
genetically engineered to make
biotechnology products.
• Organisms that have had a foreign gene
inserted into them are called transgenic
organisms.
• There are now transgenic bacteria,
transgenic plants, and transgenic
animals.
• Recombinant DNA technology is used to
produced transgenic bacteria, which are
grown in huge vats called bioreactors.
• Transgenic bacteria are used to produce:
insulin, human growth hormone, tissue
plasminogen activator, and hepatitis B
vaccine.
• They also add insecticidal toxins to
plants, reduce frost damage on plants,
degrade wastes, produce chemicals, and
help mine metals.
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Transgenic Plants
Transgenic Animals
• Foreign genes are added to protoplasts
using an electric current.
• Foreign genes in cotton, corn, and
potatoes have given them pest
resistance; soybeans are made resistant
to herbicide for no-till farming.
• Transgenic plants produce human
hormones, clotting factors, and
antibodies in their seeds; one weed has
even been engineered to produce plastic
granules.
• Foreign genes can be inserted into animal
eggs.
• Gene pharming uses transgenic farm
animals to produce pharmaceuticals in
their milk.
• Animals may produce drugs for the
treatment of cystic fibrosis, cancer, and
blood diseases.
Transgenic animals
Cloning Transgenic Animals
• Cloning of mammals was once
considered impossible, but has now been
accomplished with sheep, calves and
goats.
• A 2n nucleus from a bioengineered
animal is inserted into enucleated eggs
from a donor.
• A surrogate mother gives birth to the
cloned animals.
Animal Organs as Biotechnology
Products
• Scientists are genetically engineering
pigs to serve as organ donors for humans
who need transplants.
• Transplants of organs across species is
called xenotransplantation.
• Researchers are trying to make organs
less antigenic to humans.
The Human Genome Project
The Human Genome Project has two
goals:
(1) to construct a map that shows the
sequence of bases on all the human
chromosomes and
(2) to construct a map that shows the
sequence of genes along all the
human chromosomes.
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The Base Sequence Map
Genetic map of chromosome 17
• The first goal has been completed and
researchers know the sequence of three
billion base pairs after 15 years of
research.
• The two agencies that completed the task
are The International Human Genome
Sequencing Consortium and Celera
Genomics, a private company.
The Base Sequence Map
• A gene map could help discover mutant
genes and lead to the development of
medicines to treat these disorders.
• Germline therapy, that is done before a
child is born, may eventually be possible.
• Many ethical questions surround how
human genome maps should be used.
Gene Therapy
• Gene therapy is the insertion of genetic
material into human cells for the
treatment of a disorder.
• A patient would be given healthy genes to
make up for any faulty genes.
• Many researchers are trying to cure
cancer by inserting genes to make
healthy cells tolerant of chemotherapy or
use a gene (p53) to bring about the death
of cancer cells.
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