Download Genetic Engineering

Genetic Engineering
The principles of genetics are being used to change the world!
Chapter 13
Honors Living Environment
Mrs. Mascia
€
€
€
How are these
organisms different?
Are they the same
species?
Who
h is involved
l d with
h
making these
variations?
•
How are these
apples different?
•
Are they the same
species?
•
Who iis involved
Wh
i
l d with
i h
making these
variations?
Selective Breeding
•
•
Selective breeding,
g or artificial selection, is
when people take control and cross
organisms with selected traits.
Humans use selective breeding to pass
desired traits on to the next generation
of organisms.
– For example,
e ample domestic dogs are bred for
desirable physical characteristics and health
traits.
– For example,
example most crop plants are crossed for
desirable tolerances to temperatures and
diseases.
Selective Breeding (cont
(cont’d)
d)
€
American botanist Luther Burbank
developed the disease-resistant
Burbank p
potato in the late 1800s –
which aided in fighting the Irish potato
blight.
g
To do this, he used Hybridization.
y
Hybridization
Hybridization = the process of crossing
dissimilar individuals to bring together
the best of both organisms
g
€ Hybrids = make hardier individuals
€
Inbreeding
Inbreeding = the continued breeding of
individuals with similar characteristics
€ One major problem: Inbreeding is more
likely to cross two recessive alleles
producing genetic defects
€
Concept Map
Section 13
13-1
1
Selective
Breeding
consists
of
Inbreeding
Hybridization
which
crosses
which
crosses
Similar
organisms
Organism
breed A
Organism
breed B
Organism
breed A
which
Retains
desired
characteristics
Go to
Section:
for
example
for
example
Dissimilar
organisms
which
Combines
desired
characteristics
What about Variation?
Some scientists try to preserve the
diversity in our world
€ Other scientists try to increase the
diversity in our world = more variation!
€ Breeders can increase the genetic
variation in a population by inducing
mutations, which are the ultimate
source of genetic variability!
€
Mutations
Remember: Mutations are inheritable
changes in DNA
€ You can wait for mutations to occur
spontaneously, or you can increase the
rate of mutations by using radiation or
chemicals
€ Mutations can be harmful or desirable
to an organism!
€
Some Mutant Examples
€
New Bacteria: Scientists have been able to
develop hundreds of useful bacterial
strains with mutations.
y For
F example,
l bacteria
b t i th
thatt digests
di
t oilil and
d cleans
l
water after oil spills
€
New Plants: Scientists have been able to
develop drugs that prevent chromosomal
separation during meiosis in plants
(polyploidy )
(polyploidy.)
y For example, polyploid plants have many sets of
g and hardier
chromosomes and are often larger
This is all Genetic Engineering!
•
Genetic engineering
g
g changes
g the
arrangement of DNA that makes up a gene.
Genes can also be inserted into cells to change
how the cell performs
performs.
• For example, large volumes of medicines, such as
insulin, can be produced by bacteria given the insulin
gene or plants resistant to certain diseases can be
developed.
•
Biotechnology is a branch of science studying
genetic engineering
g
g
g and changing
g g the way
y we
interact with the living world.
Other Uses of Genetic Engineering
•
In the past, people bred for organisms with desired traits by
selective breeding, but now people can insert genes (DNA)
into cells to produce organisms with those same desired
traits by genetic engineering (Cell Transformation)
•
•
Gene therapy is a form of genetic engineering that inserts a normal allele
into a virus that attacks a target cell and inserts the normal allele into the
body cell.
Cloning is the process of making a new identical copy of an
organism from a single adult cell. Cloning can occur naturally
as identical twins, or by genetically engineering plants and
animals, endangered or extinct species, a deceased pet or
stem cells.
•
Stem cells are the cells that all of your cells “stem” from. Stem cells can be
used to determine the function of specific genes, manipulate genes, or make
new cells or tissue to treat injuries or diseases.
Let’ss Review
Let
€
Selective Breeding:
y Hybridization = dissimilar individuals
y Inbreeding = similar individuals
Let’ss Review
Let
€
Increasing variation:
y Mutations = alter/change DNA
y Polyploidy = interfers with meiosis by not
allowing chromosomes to separate.
Let’ss Review
Let
€
Genetic Engineering:
y Cell Transformation = insert foreign DNA into
a cell
y Cloning = use a single adult cell to produce
a genetically identical duplicate individual
€
What do you think are some of the pros
and cons of genetic engineering?
Pros and Cons of Genetic
Engineering
€
Pros
Better Taste,, Nutrition and Growth Rate
Crops like potato, tomato, soybean and rice
are currently being genetically engineered
to obtain new strains with better nutritional
qualities and increased yield. The
genetically engineered crops can be used
to impart a better taste to food.
Pest-resistant Crops and Longer Shelf life
Engineered seeds are resistant to pests
and can survive in relatively harsh climatic
conditions. It can thus result in fruits and
vegetables that have a greater shelf life.
Genetic Modification to Produce New
Foods
Genetic engineering in food can be used to
produce totally new substances such as
proteins and other food nutrients. The
genetic modification
f
off foods
f
can be used
to increase their medicinal value, thus
making homegrown edible vaccines
available.
€
Cons
May
y Hamper
p Nutritional Value
Genetic engineering in food involves the
contamination of genes in crops.
Genetically engineered crops may
supersede natural weeds. They may prove
to be harmful for natural plants
plants.
May Introduce Harmful Pathogens
Horizontal gene transfer can give rise to
new pathogens. While increasing the
immunity to diseases in plants, the
resistance genes may get transferred to the
harmful pathogens.
May Lead to Genetic Defects
Gene therapy in human beings can have
certain side effects. While treating one
defect, the therapy may lead to another.
Detrimental to Genetic
G
Diversity
Genetic engineering can hamper the
diversity in human beings. Cloning can be
detrimental to individuality.
In recent years, new varieties of farm plants
and animals have been engineered by
manipulating
p
g their g
genetic instructions to
produce new characteristics.
€ In
the past
past, variation was limited
to the variations already in nature
or random
d
variations
i ti
th
thatt resulted
lt d
from mutations.
€ Now, scientists can change DNA
and swap genes from one
organism to another, designing
new living things.
things
Molecular Biology Tools
Remember: Genetic engineering is
making changes to DNA
€ The steps include:
€
y DNA extraction (removal)
y Cutting DNA
y Separating DNA
y Making copies of DNA
DNA Extraction
€
Using a simple
chemical procedure,
cells are opened and
DNA is separated
and removed from
th other
the
th cellll parts.
t
€
Have you ever had to cut something very small at a precise
spot?
p
How did yyou determine where and how to cut it? What
did you end up with?
€1.
Look at the series off DNA nucleotides on your sheet off paper.
GTACTAGGTTAACTGTACTATCGTTAACGTAAGCTACGTTAACCTA
€2.
Look carefully at the series, and find this sequence of letters:
GTTAAC. It may appear more than once. Highlight the sequence
every time you see itit. How many occurrences of the sequence
GTTAAC can you find?
€3.
When you find it, divide the sequence with a mark of your
pencil. You will divide it between the T and the A. This produces
short
s
o t seg
segments
e ts o
of DNA. How
o many
a y ttimes
es would
ou d you cut tthe
e
DNA? How many fragments have 6, 10, & 15 bases?
Cuttingg DNA
€
DNA is too large to be analyzed, so it is
precisely
i l cutt iinto
t smaller
ll fragments
f
t
using restriction enzymes
y Each
E h restriction
t i ti enzyme cuts
t DNA att a
specific sequence of nucleotides
○ EcoRI codes for CTTAAG and cuts at GAATTC between the
G and the A
○ Bam I codes for CCTAGG and cuts at GGATCC between the
Gs.
○ Hae III codes for CCGG and cuts at GGCC between the G
and the C
○ Hind III codes for TTCGAA and cuts at AAGCTT between the
As
Restriction Enzymes
Recognition sequences
DNA sequence
Restriction enzyme
EcoRI cuts the DNA
i t fragments.
into
f
t
Sticky end
Restriction Enzymes
Recognition sequences
DNA sequence
Restriction enzyme
EcoRI cuts the DNA
into fragments.
Sticky end
Separating DNA
€
DNA fragments are separated and
analyzed using gel electrophoresis.
y DNA is placed at one end of a gel and an
electric current pulls negatively charged
DNA molecules toward the positive end of
the gel
g
y Smaller DNA fragments move faster and
farther across the gel
y Gel
G l electrophoresis
l
h
i iis used
d to compare DNA
of different organisms or identifying one
particular g
p
gene
http://www.dnalc.org/ddnalc/resources/electrophoresis.html
Gel Electrophoresis
Power
source
DNA plus restriction
enzyme
Longer
fragments
Shorter
fragments
Mixture of DNA
fragments
Gel
DNA Sequencing
€
Now that the DNA is in manageable form, the
DNA sequence can be read, studied or
changed to study specific genes, compared to
genes off different
diff
t organisms,
i
and
d one can ttry
to identify the function of the different genes.
Reading the DNA sequence:
€
€
€
€
Obtain a single
g stranded p
piece of an
organism’s DNA.
As it replicates with bases labeled with
color coded fluorescent dyes
dyes, the
replication stops, forming a fragment.
After all of the DNA has replicated, tiny
l b l d ffragments
labeled
t are lleft.
ft
The fragments are separated by gel
electrophoresis
e
ect op o es s a
and
d tthe
e patte
pattern o
of tthe
e co
color
o
coded fragments is read, telling scientists
the exact DNA sequence.
DNA Sequencing
Fluorescent
dye
Single strand
off DNA
Strand broken
after A
Power
source
Strand broken
after C
Strand broken
after G
Strand broken
after T
Gel
Cutting and Pasting
€
€
Now that the DNA
sequence is known,
it can be changed.
S i ti t can ttake
Scientists
k
a gene (piece of
DNA) from one
organism and
attach it to the DNA
off another
th organism
i
= Recombinant
DNA (combined
(co b ed
DNA)
Making Copies
€
Scientists need many copies of a gene
to study it, so they use a polymerase
chain reaction (PCR):
(
)
y Scientists add primers (short complementary
pieces of DNA) to both ends of the gene, the
double stranded DNA is separated into
single strands, then DNA polymerase makes
copies of the DNA between the primers
primers, and
each copy serves as another template.
PCR
DNA polymerase adds
complementary strand
DNA heated to
separate strands
DNA fragment
to be copied
PCR
cycles 1
2
DNA
copies 1
2
3
4
4
8
5 etc.
16 etc.
During transformation, a cell takes in DNA from
outside the cell, and the external DNA becomes
a part of the cell
cell’s
s own DNA
Plasmid
Is a small circular DNA molecule found
naturally in some bacteria.
€ The plasmid has a genetic marker which
is a gene that makes it possible to
distinguish bacteria that carry the
Plasmid (meaning the foreign DNA) from
those that don’t.
€
Bacterial DNA
Recombinant DNA/plasmid
Quick Review
€
Different enzymes
y
can be used to cut, copy,
py and
move segments of DNA.
€
Characteristics produced by the segments of DNA
may be expressed when these segments are
inserted into new organisms, such as bacteria.
€
Inserting, deleting, or substituting DNA segments
genes. ((mutations))
can alter g
€
An altered gene may be passed on to every cell
that develops from itit.
Transforming Bacteria
€
€
Bacteria can be transformed using
recombinant DNA.
Foreign
g DNA jjoins to a small circular DNA
called a plasmid, which are naturally found
in some bacteria.
y It serves as a bacterial origin of replication (it will
be replicated if it gets inside the bacterial cell)
y It has a genetic marker (a gene that is
distinguishable between bacteria with/without
the foreign DNA)
http://www.dnai.org/text/mediashowcase/index2.html?id=549
Making Recombinant DNA
Recombinant
DNA
Gene for human
growth hormone
Gene for human
growth hormone
Human Cell
Bacterial Cell
Bacterial
chromosome
Plasmid
Sticky
ends
DNA
recombinatio
n
DNA
insertion
Bacterial cell for
containing gene for
human growth hormone
http://www.bioteach.ubc.ca/TeachingResources/Applications/
GMOpkgJKloseGLampard2.swf
Transformingg Plant Cells
In nature, there’s a bacteria that can
insert a p
plasmid into p
plant cells,,
producing tumors. Scientists use this
same bacteria, but insert foreign DNA,
producing
d i a recombinant
bi
t plasmid
l
id th
thatt
can infect plants.
€ OR,
OR DNA can be injected into some
cells.
€ OR,
OR scientists can remove the cell wall
and allow plant cells to take up the DNA
on their own
€
http://www.bioteach.ubc.ca/TeachingResources/Applications/GMOpkgJKloseGLampard2
.swf
Transforming Plant Cells
€
Either way,
y, if transformation is successful,, the
recombinant DNA is integrated into one of the
chromosomes of the cell, the cell can be cultured
(to make more cells) to produce adult plants
plants.
Transforming Animal Cells
€
DNA can be injected into egg cells and
enzymes in the cell will insert the foreign
DNA into the chromosomes of that cell.
http://www.youtube.com/watch?feature=pla
yer_embedded&v=YXPnQvcqHkg#!
Are They “Designer”
Scientists?
€
Scientists can insert foreign
DNA that will recombine with
specific sequences in a host
chromosome, “knocking out”
or replacing the host gene
with
ith a new gene.
y Used to study specific functions
of genes,
genes possibly treat
disorders caused by single
genes (gene therapy), or
possibly
ibl design
d i b
babies,
bi
etc…
t
€
Using your knowledge of genetic engineering,
explain how the plant and dog glow.
A genetically modified virus was
used to inject the new genetic
code directly into a stem cell
nucleus.
l
Th t nucleus
That
l
was th
then
inserted into a de-nucleated egg
cell and placed in a surrogate
mother. An eating,
g, sleeping,
p g,
glowing (literally) puppy!!!
A firefly’s gene
(for the enzyme
luciferase) was
inserted into a
tobacco plant
cell, then that
cell was
cultured
producing
tobacco plants
that glow!!!
Transgenic
€
What does the word transgenic mean?
y Trans = across
y genic = the genes
Making organisms that contain genes
from other organisms
organisms.
€ Genetic engineering has spurred the
growth of a whole new branch of
biology: biotechnology!
€
Biotechnology
€
Knowledge of genetics is making
possible new fields of health care:
y Finding genes which may have mutations
that can cause disease will aid in the
development of preventive measures to fight
disease
di
y Substances, such as hormones and
enzymes from genetically engineered
enzymes,
organisms may reduce the cost and side
effects of replacing
p
g missing
g body
y chemicals.
Transgenic Microorganisms
€
Transgenic bacteria produce many
important substances for health and
industry,
y, because theyy reproduce
p
quickly and are easy to grow:
y Human forms of proteins, including insulin,
growth hormone, and clotting factor are being
produced.
Future Transgenic Microorganisms
€
In the future
future, transgenic microorganisms
may produce:
y Substances to fight cancer
y Raw materials for plastics or synthetic fibers
Transgenic Plants
€
Much of our food supply, especially beans
and corn, is transgenic or genetically
modified (GM).
y Many crop-grown GM plants now contain genes
that produce a natural insecticide or resistance
to chemicals or diseases
diseases.
€
One of the greatest GM plants developed
was a rice
i plant
l t th
thatt adds
dd vitamin
it i A to
t rice!
i !
This was HUGE for nations
with
ith starving
t i populations.
l ti
Future Transgenic plants
€
In the future
future, transgenic plants may
produce:
y Human antibodies that can fight diseases
y Foods resistant to rot and spoilage
Transgenic Animals
€
Used to study genes and
improve food supplies, for
example:
p
y Mice with immune systems
similar to humans are used to
study how diseases may affect
humans.
y Livestock
Li
t k with
ith extra
t growth
th
hormone genes grow faster
and
a
dp
produce
oduce leaner
ea e meat
eat
Future Transgenic Animals
€
In the future
future, transgenic animals may
produce/become:
y Chickens resistant to bacterial infections that
cause food poisoning
y Human proteins: for example, sheep and
pigs that produce human proteins in their
milk.
Stem Cells
Stem cells are derived from human
embryos before the cells differentiate.
€ The embryonic stem cells can combine
with nuclei of differentiated tissue
needed.
€ A new tissue can be cultured and used
to “heal”
heal a person by replacing damaged
tissue.
€
Future Stem Cells?
€
Future stem cells could be used in
treating:
y Parkinson
Parkinson’s
s Disease
y Alzheimer’s Disease
y Diabetes
y Spinal Cord injuries
Cloning
Clone = member of a population of
genetically identical cells produced from
a single
g cell
€ Cloning unicellular organisms is easy,
but it took a long time for scientists to
clone a multicellular organism.
€
y Sheep,
p, cows,, p
pig,
g, mice and other mammals
have been cloned
Cl i
Cloning
A body cell is taken from a donor animal.
An egg cell is taken from a donor animal.
The nucleus is removed from the egg.
egg
The body cell and egg are fused by electric shock.
The fused cell begins dividing, becoming an embryo.
The embryo is implanted into the uterus of a foster mother.
The embryo develops into a cloned animal.
Cloning of the First Mammal – Dolly!!!
A donor cell is taken from
a sheep’s udder.
Donor
Nucleus
These two cells are fused
using an electric shock.
Fused Cell
Egg Cell
The nucleus of the
egg cell is removed.
An egg cell is taken from
an adult female sheep.
Cloned
Lamb
The fused cell
begins dividing
normally.
Embryo
The embryo
develops
normally into a
lamb—Dolly
Foster
Mother
The embryo is placed
in the uterus of a foster
mother.
Future Clones?
€
€
€
C
Clones
are not necessarily
y transgenic,
g
, but
scientists hope to use cloning to make copies of
transgenic animals that produce genetically
engineered substances
substances.
In the future, cloning could possibly save
endangered species.
Or possibly humans??? Æ Ethical issues?!