Genetic Engineering

Download Report

Transcript Genetic Engineering

Genetic Engineering
Chapter 13 (Sections 1, 2 and 4)
13-1: Changing the Living World
• What is the purpose of selective breeding?
• Why might breeders try to induce
Selective Breeding
• Selective breeding is allowing animals with
desired characteristics to produce the next
– Humans use selective breeding to pass desired traits
on to the next generation of organisms
• Hybridization is the crossing of two dissimilar
organisms to bring together the best of both
• Inbreeding is the continued breeding of
individuals with similar characteristics and
Selective breeding has been used for
thousands of years to produce better crops
Hybridization can be used
to combine useful
characteristics from
different organisms
For Example: Horse +
Donkey = Mule
Crossing a male lion
and a female tiger
produces a liger.
(Reverse the sexes
and you get a Tigon)
Inbreeding can be
used to maintain
desired characteristics
Increasing Variation
• Breeders can increase the genetic variation in a
population by inducing mutations (the ultimate
source of variability)
• Breeders increase the mutation rate with radiation
or chemicals
• Scientists have been able to develop useful
strains of bacteria, and produce polyploidy
(many sets of chromosomes) in plants (stronger
and larger plants)
Polyploidy results in
larger fruits, flowers,
and plants
13-2: Manipulating DNA
• Scientists use their knowledge of the
structure of DNA and its chemical
properties to study and change DNA
• Different techniques are used to extract
DNA from cells, to cut DNA into smaller
pieces, to identify the sequence of bases in a
DNA molecule, and to make unlimited
copies of DNA
The Tools of Molecular Biology
• Genetic engineering is making changes to the
DNA code of a living organism
The Tools of Molecular Biology
• Cutting DNA: Restriction enzymes cut
DNA at specific sequences of nucleotides
• PCR – Polymerase Chain Reaction can
make multiple copies of the cut sequence
The restriction enzyme EcoR I, for example, finds the sequence CTTAAG on
DNA. Then, the enzyme cuts the molecule at each occurrence of CTTAAG. The
cut ends are called sticky ends because they may “stick” to complementary
base sequences by means of hydrogen bonds.
The Tools of Molecular Biology
• DNA extraction: Cells are opened and the
DNA is separated from other cell parts
The Tools of Molecular Biology
• Separating DNA: Gel electrophoresis
separates pieces of DNA based on their size
– Used to compare genomes or locate genes
* Using the DNA Sequence *
• Once DNA is in a manageable form, its
sequence can be read, studied, and even
• Knowing the sequence of an organisms DNA
allows researchers to:
– Study specific genes
– Compare genes from different organisms
– Discover the function of different genes and gene
* Using the DNA Sequence *
• Recombinant DNA makes it possible to take a
gene from one organism and attach it to the DNA
of another organism
• Polymerase Chain Reaction (PCR) is used to make
copies of a particular gene
• PCR permits early diagnosis of malignant
diseases such as leukemia and lymphomas,
which is currently the highest developed in
cancer research and is already being used
13-4: App. of Genetic Engineering
• Genetic engineering makes it possible to
transfer DNA sequences, including whole
genes, from one organism to another
• Luciferase an enzyme that allows fireflies
to glow, has been inserted into tobacco
plants, causing them to glow in the dark
Bioengineers have also developed salmon that grow to market weight
in about half the typical time, disease-resistant cows and catfish
needing fewer antibiotics, and goats whose milk might help ward off
infections in children who drink it.
This little piggy’s manure causes less pollution. This
little piggy produces extra milk for her babies. And this
little piggy makes fatty acids normally found in fish, so
that eating its bacon might actually be good for you.
•The Department of Agriculture's Agricultural Research
Service genetically engineered the cow at left to
produce an antimicrobial protein to resist infection with
Staphylococcus aureus
•Researchers at the University of Missouri-Columbia
genetically engineered the pig at right to serve as a
model of cystic fibrosis in humans.
Transgenic Organisms
• Transgenic organisms have genes from other species
• Because they reproduce rapidly and are easy to grow,
transgenic bacteria now produce many important
substances for health and industry
– insulin, growth hormone, clotting factor, etc
• Transgenic animals have been used to study genes and
improve the food supply
– Mice with human immune systems, livestock with extra growth
hormone genes
• Transgenic plants can produce natural insecticides, or
resist weed-killing chemicals
•GTC Biotherapeutics created the transgenic goat at right
as part of a project with researchers at the University of
Pennsylvania to refine strategies for genetic engineering
• A clone is a member of a population of
genetically identical cells produced from a
single cell
• Dolly the sheep was cloned by
– (1) removing the nucleus of an egg cell
– (2) inserting the nucleus from an adult cell
– (3) placing the embryo into a foster mother to
• Cows, pigs, mice and other mammals have been
• Cloning humans is scientifically possible, but
raises serious ethical and moral issues
Therapeutic cloning
• also called "embryo cloning," is intended
for medical use
• The embryonic stem cells that this type of
cloning produces can be used to create skin
for burn victims, organs for transplant
patients, or cells for those with spinal cord