Ch#13 Genetic Engineering

Inquiry

•
Is it possible to grow all 5 different
varieties of apples on one tree?”

5
-
In
-
1 Apple Tree


This miracle of genetic science offers an entire
apple orchard
-

from a single tree! "Everbearing"
tree
-

apples for eating, apples for pies, apples for
applesauce and apples for freezing. Start
producing in the summer
---

continue right through
the fall. Beautiful apple blossoms in spring!
Require little space. Sub
-
zero hardy. Self
-
pollinating tree! Grafted on dwarfing, malling
number seven rootstock grow to 12 feet tall. Apple
varieties included are:
Red Delicious,
Yellow Delicious, Dark Red
Jonathan, Yates and Winesap.

Ch#15 Genetic Engineering

Selective Breeding
-

using animals with
desired characteristics to breed

•
Nearly all domestic animals & crops have
been produced by selected breeding

Luther Burbank

•
Helped to produce a
disease
-
resistant potato
to help fight the potato
blight in Ireland that
starved many people

•
He also developed more
than 800 strains and
varieties of plants


Technique #1
----
Hybridization

•
Crossing dissimilar individuals to bring
together the best of both organisms

•
Burbank often combined a
disease
resistant trait

with a
large

food
-
producing capacity

to greatly increase crop

productivity

Technique #2
----

Inbreeding

•
Continued
breeding of

individuals with similar


characteristics

•
Often used with purebreds


of dogs & cats & horses

•
Down side
-
-
a recessive allele for a
genetic defect can easily be passed on

•
Purebred animals often have poor
immune systems and other genetic
disorders


Increasing Variation

•
Breeders can increase
genetic variation in a
population
by inducing
mutations
, which
increase genetic variation

•
Variation in every
species increases that
chances of survival of
the species during
adverse conditions in
the world

Biotechnology

•
Biotechnology

is the application
of a technological process,
invention, or method to living
organisms to produce a desired
product.


Bacteria:
millions can be
exposed to
radiation

or
chemicals

at the same time
to increase mutations

Oil eating bacteria
caused by biotech

Plants

•
Chemicals have be used to prevent
chromosomes from separating during meiosis in
some plants

•
Resulting cells
have double or triple the # of
chromosomes

(polyploidy is usually fatal in
animals)

•
Polyploidy plants
may produce a stronger
species & has been used in citrus fruits &
bananas

Mutations Cartoon

Recombinant DNA

•
Scientists use different
techniques to extract DNA
from cells, cut it into
pieces, & identify gene
sequences to make copies

•
Genetic Engineering

is
making changes in DNA &
putting the modified code
back into the living
organism

15
-
2

Finding Genes

•
In 1987, Douglass Prasher studied the
jellyfish

•
He found the GFP gene (green flourescent
protein) absorbs energy from lights &
makes parts of the jellyfish glow

•
His method of discovering the gene is
called the
Southern blot technique

•
This gene is used to label proteins in living
cells

PCR

•
Polymerase Chain Reaction (PCR
)

is a
process to
make copies of a gene
using
primers

to mark the start & stop of the sequence
& DNA polymerase from a bacteria in a short
time

•
Primers
create a place for DNA polymerase to
start its work building new DNA strands.

•
Kary Mullis invented PCR by using bacteria,
Thermacus aquaticus
from the hot springs of
Yellowstone National Park

•
It is thermophilic & can withstand the heating
process

DNA Sequences

•
3 things needed for
PCR:

1.
Primers

2.
DNA polymerase

3.
Tagged nitrogen bases

•
Recombinant DNA

,
DNA from different
sources recombined in a
new sequence, in this lab
assembled DNA

Cell Transformation

•
When a cell takes in DNA
from outside the cell
making it a new
component of its DNA

•
Scientists use this
technique on bacteria in
the lab

•
A
plasmid

is a circular
DNA molecule found in
bacteria

Genetic marker

•
A
genetic marker
is a gene that makes it
possible to distinguish bacteria that carry
the plasmid from other bacteria

•
New antibiotics are being made because
bacteria have mutated that can resist older
antibiotics

•
These “
Antibiotic Resistant” bacteria
can
transfer this plasmid to other bacteria so
that they can be resistant, too

Transforming Plant Cells

•
Geneticists use bacteria to insert a plasmids for
certain foreign DNA into plants

•
These plants are then “
transgenic
” (having DNA
from more than one organism)

•
More recently, a gene has been introduced into
tomato that delays
overripening

and prolongs
shelf life of the fruit.


Transgenic Animal Cells

•
Many eggs are large enough to inject new DNA
directly into the nucleus

•
Enzymes in the nucleus then “repair” the DNA into
the chromosomes

•
The objective is to produce animals which possess
the transferred gene in their germ cells (sperm or
ova).
Such animals are able to act as "founder"
stock to produce many offspring that carry a
desirable gene or genes.

Cloning

•
A member of a population that is
genetically identical produced from a
single cell

•
In 1997, Scottish scientist Ian Wilmut
produced a cloned sheep “Dolly”

•
He fused
an egg with another adult
body cell DNA
& placed this embryo
into a foster mother to grow

•
Scientists are hoping to use this
technique to save endangered
species

•
Unfortunately,
Dolly was born
having cells that
were already the
same age as the
body cells used to
clone her, so she
did not live long

Applications of Genetic
Engineering

15
-
3

•
Ideally, genetic modification could lead to
better, less expensive, & more nutritious
food as well as less
-
harmful
manufacturing
processes

•
In the U.S., most of our
crops are GM

•
Plants resistant to pests,
herbicides, & viruses grow
better & yield larger crops

GM Animals

•
Animals have extra


growth hormone inserted to

produce livestock that grow


faster & produce leaner meat

•
There are sheep, pigs, &


cows that
produce human

proteins & antibodies in their milk


Spider genes were inserted
into goats to create silk in
their milk

Health & Medicine

•
Recombinant
-
DNA technology is the source of
some of the most important & exciting
advances in the prevention & treatment of
disease

•
Golden rice
contains increased amounts of
provitamin A (beta
-
carotene) that is an
essential vitamin

•
Deficiencies in provitamin A can include infant
blindness

Gene Therapy

•
The process of changing a gene to treat
a medical disease or disorder

•
This will be done by replacing a defective
gene with a healthy one or ‘fixing’ the
defective gene


The challenge is to be
reliable enough to ensure
that the DNA used in the
therapy does no harm to
the patient


Examining Active Genes

•
DNA microarray:
silicon chip
used to study thousands of
genes at once

•
DNA fingerprinting:
analyzes
sections of DNA that are
unique in each person

•
Forensics:
crime scene
evidence scientific study

Ethics & Impacts

•
Biotechnology has raised new issues

1.
Privacy
: patents for new biotech & the Genetic
Information Nondiscrimination Act to protect
individual DNA information

2.
Safety
: GM crops/animals have been available
for a decade & no problems so far, however
many are concerned that long term affects are
still unknown

15
-
4

Is this the future?

Cons of GM Foods

•
Many people are concerned about
unintended consequences of biotech

•
Small farmers who can’t afford GM seeds
may go out of business

•
Currently, no labels identify GM products

1.
foods may become allergenic or toxic

2.
may promote antibiotic resistance, making it
difficult to treat human disease

3.
GM crops may cross
-
pollinate with other
plants

Concerns