Gene Technology
I. Genetic Engineering
A. Basic Steps of Genetic Engineering
1. Genetic Engineering – Manipulation of DNA for
practical purposes
2. Restriction enzymes – enzymes that cut DNA into
fragments that have short sticky ends.
3. Steps in a Genetic Engineering Experiment
a. Cut DNA (using restriction enzymes)
b. Recombinant DNA is produced
c. The gene is copied
d. Cells are selected and screened for gene of interest
4. Cutting DNA and Making Recombinant DNA
a. Restriction enzymes are used to generate
“sticky”ends.
b. Sticky ends allow DNA fragments from different
organisms to join together to form recombinant
DNA.
5. Cloning, Selecting and Screening Cells
a. Recombinant DNA is inserted into host cells.
b. Each time the cells reproduce, the gene of
interest is copied.
c. The cells are then screened to indentify cells that
have the recombinant DNA.
B. Confirmation of a Cloned Gene
1. Gel Electrophoresis – uses an electric field within a
gel to separate DNA fragments by their size.
2. Specific genes can be indentified with DNA or RNA
probes using the Southern Blot technique
Gel Electrophoresis
C. DNA fingerprinting
1. A DNA fingerprint is a restriction fragment
electrophoretic pattern made from biological samples.
a. DNA is extracted and cut into segments using
restriction enzymes and are separated by
electrophoresis.
b. The segments are radioactively tagged to produce a
visual pattern known as a radiograph or “DNA
fingerprint” on X-ray film
2. DNA fingerprints are used to identify suspects at a
crime scene, paternity or genetic disorders.
3. It depends on the fact that no two people, except
identical twins, have exactly the same DNA sequence.
II. Human Applications of Genetic Engineering
A. The Human Genome Project
1. An effort to determine the nucleotide sequence and map
the contents of every gene on each human chromosome.
2. Large amounts of DNA do not encode for proteins
3. Human cells contain about 30,000 to 40,000 genes
B. Genetically Engineered Drugs and Vaccines
1. Genetic engineering is used to manufacture human
proteins for use as drugs.
2. Genetic engineering is used to manufacture virus
components for making safer and more effective
vaccines
Genetically
Engineered
Human Insulin
III. Genetic Engineering in Agriculture
A. Improving Crops
1. Plants can be genetically engineered to have
desirable characteristics; including increased yields
and resistance to herbicides and destructive pests
2. Plants can also be designed to have improved
nutrition value; such as rice enriched with iron and
vitamin A.
B. Risks of Genetically Modified Crops
1. There may be unforseen negative effects of using
genetically modified crops that are immune to
herbicides and there may be a possibility of causing
allergies.
2. There may be a possibility of GM genes being
introduced into foreign organisms
Genetically modified strawberry
A gene was added which causes it
to be blue.
Pizzamatoes – tomatoes which
have been genetically modified to
exhibit characteristics of basil,
garlic and oregano.
C. Gene Technology in Animal Farming
1. Genetically engineered growth hormone can increase
milk production in dairy cows and weight in cattle and
hogs.
2. Transgenic animals have foreign DNA introduced to
their cells.
a. Human genes could be introduced into farm animals
which could produce human proteins in their milk
b. Genes from spiders have been introduced into goats
who produce milk which has spider silk proteins
D. Cloning from Adult Animal cells
1. Cloning of farm animals from adult cells was first
accomplished in 1997 when Dolly, a sheep, was born to
a surrogate mother.
2. Various other animals have since been cloned; cats,
cattle, dogs, goats, horses, and rhesus monkeys
3. Cloning has not been perfected. There are problems
which are due to the fact that genetic imprinting
(preparation) occurs in the sperm and egg cells prior to
fertilization. Cloned cells do not undergo this process
and many cloned animals have developmental
problems.
Dolly
Scotland's Dolly the sheep was
the world's first cloned
mammal.
CC
Left - Cell Donor
Middle - Cloned Dog
Right - Surrogate Mother
Rhesus monkey
The End