Ch#13 Genetic Engineering

deadstructureBiotechnology

Dec 14, 2012 (4 years and 8 months ago)

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Inquiry


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-
In
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-

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---

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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