Download Genetic Engineering

We have been manipulating DNA
for generations!
• Selective breeding
– Allowing only those animals/plants with
desired characteristics to produce the next
generation (foods, vaccines, bidegeneration,
antibiotics, vitamins)
Animal Breeding
Breeding Food Plants

“Descendants” of the wild mustard
 the “Cabbage family”
Corn from tiosinte plants
Using mutations to increase
genetic diversity
Selective breeding/artificial breeding would
not be possible if it were not for the large
amounts of diversity
 Biologists/geneticists can increase this
diversity by causing mutations in a DNA
sequence

 Ex: using this technique scientists have
developed several different kinds of helpful
bacteria
○ Bacteria that can digest oil and were once used to
clean up oil spills
How Can We Do This?

We manipulate the DNA!
 Genetic engineering-making changes in the
DNA code of a living organism
Can an animal gene be put into a
plant or vice versa?
YESSSS!!!!
 Steven Howell and his associates
isolated the gene that allows fireflies to
glow (luciferase), and inserted it into
tobacco cells. When these cells were
grown into a plant, the entire plant glew
in the dark.

Transgenic Organisms

Bacteria
 Used most often because of how quickly
they reproduce
 Genes are spliced in the bacterial DNA;
bacteria produce proteins that are coded for
in gene; cheap and in great abundance
○ Ex: Insulin
 People with insulin-dependent diabetes are now
treated with pure human insulin produced by human
genes that were inserted into bacteria
Gene splicing
Transgenic Animals
Genes from humans have been inserted
into mice to improve their immune
systems so that we can use them to test
the effects of diseases on the human
immune system
 Growth hormone is added to have
animals grow faster, produce leaner
meat
 Blood clotting factor mass produced in
pigs

Mice from the same litter
Transgenic plants





In 2000, 52 percent of soy bean and 25
percent of corn grown in the U.S. was
transgenic or genetically modified
GMO (Genetically modified organisms)
Contain genes that produce natural
insecticides so that they don’t have to
sprayed
Some contain genes that prevent them
from being killed by weed killers
Some strawberries and other fruits contain
anti-freezing agent found in arctic flounder
What’s next?
Plants may soon be used to produce
human antibodies that can be used to
fight disease
 Foods that may be resistant from rot
 Chicken that is immune to the bacteria
that cause food poisoning
 Exists already-rice containing Vitamin A
which our body produces, increases
health of millions around the world

What about humans?
Is it ethical to genetically modify
humans?
 Should we be able to alter a human’s
DNA?
 Should there be boundaries drawn?

What already exists?

The Human Genome Project
 Contains over 6 billion basepairs
 That is 6,000,000,000 A,T, G, and C’s
 E.Coli (a bacteria) contains 4,639,221 bps

In 2000 a working copy of the human
genome was essentially complete
 Allows us to look at the human DNA
sequence and determine where specific
genes are located
Genetic Testing

Genetic testing is now used for:
 Carrier screening, or the identification of unaffected individuals








who carry one copy of a gene for a disease that requires two
copies for the disease to manifest;
Confirmational diagnosis of symptomatic individuals;
Determining sex;
Forensic/identity testing;
Newborn screening;
Prenatal diagnostic screening;
Presymptomatic testing for estimating the risk of developing
adult-onset cancers;
Presymptomatic testing for predicting adult-onset disorders.
Some genetic tests are already available, although most
of them are used in developed countries. The tests
currently available can detect mutations associated with
rare genetic disorders like cystic fibrosis, sickle cell
anemia, and Huntington’s disease.
Gene Therapy

Because of the Human Genome Project,
we may soon be able to
 Cure genetic disorders by gene therapy
 An absent or faulty gene is replaced by a
normal, working gene
 This way, the body can make the correct
protein or enzyme it needs, which eliminates
the disorder.
Cloning
Dolly the sheep was cloned in 1997.

Clone-member of a population of
genetically identical cells produced from
a single cell
Researchers hope
that cloning will
enable them to make
copies of transgenic
animals and even
help save
endangered species.
-Many suffer from
genetic defects and
health problems.
Cloning in Fruits
Grafting-tissues of one plant are
inserted into those of another in order to
get desired characteristics
 Example: Apples
 Some apples cannot be grown from
seeds. So they use grafting as a way to
clone those apple types

How’s cloning work?
Cloned cows, pigs, sheep, dogs, and mice have been produced.
Stem Cells

Cells that have the ability to form any
type of cell, which could therefore, be
used to grow any type of cell that is
needed.
What do you think?

Is the use of stem cells ok?

How should they be limited, if used at
all?

What are the potential benefits and
dangers?
Biotechnology

What can be done with DNA?
 Polymerase Chain Reaction (PCR)
 Testing for Specific Alleles
 DNA Fingerprinting
Things to think about?

Who controls your DNA?
 Use by the U.S. Department of Defense?
 Employers using it to discriminate against
people carrying certain genes?

Do Genetically Modified foods need
stricter controls?
 Pg 330
How do forensic scientists figure out who
committed a crime from a single drop of blood or
a single hair?

Polymerase Chain Reactions
 Makes mass copies of a specific gene
 DNA is heated to different temperatures in
order to break strands apart, primers are
added, and DNA polymerase is added to
make copies
 DNA polymerase came from bacteria in the
hot springs in Yellowstone National Park
PCR
DNA Fingerprinting
Helps identify individuals
Does not focus on cell’s
most important genes
because they are all so
similar in every human
 Instead focuses on
sections of DNA that
have little or no known
function but vary widely
from person to person



Restriction enzymes-enzyme that cuts
DNA at a specific sequence of
nucleotides
1) DNA is collected and run through
PCR to increase sample of DNA
 2) Restriction enzymes are added that
locate specific sequences in the human
DNA and cut DNA into fragments of
various lengths

3) These different size samples are
loaded into an agarose gel where they
bands are separated using an electrical
current.
 4) A buffer is placed in the
electrophoresis chamber before the
DNA is run to provide a stable pH and
help conduct the electrical current.
 Agarose gel-a pourous gel used to
separate different strands of DNA


DNA has a negative charge!!!

When the DNA is placed in the gel and
the gel in run, which direction will the
DNA travel?
The smaller bands of DNA will travel the
farthest down the gel, because they can
easily travel through the agarose.
 The gel is stained and the DNA
fragments are compared.
