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Biotechnology
Genetic engineering
• Involves manipulating the DNA of one organism
in order to insert the DNA of another organism
• Examples
• Inserting a gene for bioluminescence into
various organisms, which can be used to
study gene expression, cellular processes,
disease development, and selecting traits
which may be beneficial to humans
• Uses:
• To increase or decrease the expression of
specific genes in selected organisms
• Applications in human health (disease
prevention, preventing spread of infectious
diseases) and agriculture
• Genes can be manipulated to show
desirable traits
• Genome – all of the DNA in an organism
• Can contain millions and millions or
nucleotides
• In order to study a specific gene, DNA
tools can be used to manipulate DNA and
to isolate genes from the rest of the
genome
• Examples – restriction enzymes, gel
electrophoresis
• Recombinant DNA technology – A new DNA
molecule created by combining DNA from
two different sources
• Used to create recombinant DNA to study
individual genes and genetically
engineered organisms and in the
treatment of certain diseases
• Requires large quantities (how done – see
next slide)
• How large quantities of recombinant DNA is
made:
• Requires a carrier, or vector, such as
viruses and plasmids (small, circular,
double-stranded DNA molecules that
occur naturally in bacteria and yeast cells)
• Plasmid and DNA fragment can be joined
to make recombinant DNA
• Vector transfers the recombinant DNA into
a bacterial cell called a host cell
• Host cell then makes large quantities of
the recombinant DNA to be made
• Transgenic organisms – organisms that are
genetically engineered by inserting a gene
from another organism.
• Animals, plants and bacteria used for
research, medical, and agricultural
purposes
• Ex. of transgenic animals:
• Mice, fruit flies, and worms used to study
diseases and develop treatments
• Livestock produced to improve food supply
and human health
• Goats engineered to secrete a protein used to
prevent human blood from forming clots
during surgery
• Fish that grow faster
• Working to produce chickens & turkeys that
are resistant to disease; transgenic organisms
may someday be a source of organs for
transplants
• Ex. of trangenic plants:
• Plants have been engineered to be resistant to
insect or viral pests, such as soybeans, corn,
cotton, and canola
• Developing peanuts and soybeans that do not
cause allergic reactions, rice plants with
increased iron and vitamins that could decrease
malnutrition in Asian countries, and plants that
can survive extreme weather conditions
• Other possible crops include bananas with
vaccines for diseases like hepatitis B and plants
that produce biodegradable plastics
• Ex. of transgenic bacteria:
• Produce insulin, growth hormones, and
substances that dissolve blood clots
• Can slow the formation of ice crystals on
crops to protect them from frost damage,
clean up oil spills more efficiently, and
decompose garbage
• Human genome project (HGP)
• Completed in 2003
• Goal was to determine the sequence of the
approximately three billion nucleotides that
make up human DNA and to identify all of the
human genes
• How done?
• Each of the 46 chromosomes was cleaved
• Several restriction enzymes were used to
produce fragments with overlapping
sequences
• Fragments were combined with vectors to
create recombinant DNA
• Recombinant DNA was cloned to make many
copies, then sequenced with machines
• Computers analyzed the overlapping regions to
generate one continuous sequence
• After HGP was done, they discovered that less
than 2% of all of the nucleotides in the human
genome code for all of the proteins in the body –
same amongst all humans
• Genome is filled with long stretches of repeated
sequences that have no direct function – called
noncoding sequences – makes each of us unique.
• Gel electrophoresis – an electric current is used to
separate DNA fragments according to the size of
the fragments
Video
• DNA is loaded on the negatively charged end of
a gel
• An electric current is applied
• DNA fragments move toward the positive end of
the gel
• Smaller fragments move faster
• Unique pattern is created
• Can be used for identification; to study DNA
fragments of various sizes
• Portions of the gel containing each band can be
removed and studied
• DNA fingerprinting – involves separating the
noncoding sequences using gel
electrophoresis in order to observe the
distinct banding patterns that are unique to
every individual
• Can be used by forensic scientists to
identify suspects and victims in criminal
cases, to determine paternity, to identify
soldiers killed in war, and to free innocent
people who have been wrongfully accused
• Gene therapy
• A technique to correct mutated genes that
cause human disease
• Done by inserting a normal gene into a viral
vector. Target cells in the patient are
infected with the virus, and the recombinant
DNA material is released into the affected
cells
• Once in the cells, the normal gene inserts
itself into the genome and begins
functioning
• Recent trials involve diabetes, cancer, retinal
disease, and Parkinson’s
• Stem cell research:
• Some cells in the body can give rise to ANY
tissue type (totipotent)
• Some cells can only give rise to a few tissue
types (multipotent)
• Totipotent cells may be used to regrow lost
limbs, regenerate nerve cells, or produce
important chemicals for humans (such as
insulin)
• Source of stem cells is often human
embryos – controversial
• Cloning: making 2 organisms with identical DNA
• How done?
• Egg cell is taken from a female donor
• Chromosomes are removed from the
donor egg so the egg has no DNA
• Cells taken from donor whose DNA is to be
cloned – given chemicals to forget their
specialized roles
• Donor cell is fused with egg cell
• Egg cell is implanted into a female carrier
• Egg develops into an embryo that has the
same DNA as the donor
• Possible uses for cloning:
• Cloning transgenic animals for medical
study
• Cloning stem cells for research
• Reviving extinct or endangered
organisms
• Cloning organs for transplant
• Human cloning could even be
possible…yet is very controversial