Download Biology

13–2
Manipulating DNA
A. The Tools of Molecular Biology
1. DNA Extraction
Homogenization: Cell walls, membranes, and nuclear material are
broken
Emulsification: Soap and enzymes break down membranes and
emulsify lipids and proteins.
Precipitation: Alcohol is layered on top of the solution. DNA is not
soluble in alcohol and precipitates either in the alcohol or at the
interface between the alcohol and the rest of the mixture.
Collection: DNA can be pulled up from the interface or alcohol with a
paper clip or glass rod.
13–2
Manipulating DNA
2. Cutting DNA
“Restriction Enzymes”
Cut DNA at precise locations,
Cut a specific sequence of nucleotides
13–2
Manipulating DNA
2. Cutting DNA “Restriction Enzymes”
Cut DNA at precise locations, Cut a specific sequence of nucleotides
Recognition
sequences
DNA
sequence
Restriction enzyme
EcoRI cuts the DNA
into fragments.
Sticky end
13–2
Manipulating DNA
2. Cutting DNA “Restriction Enzymes”
Cut DNA at precise locations, Cut a specific sequence of nucleotides
Recognition
sequences
DNA
sequence
Restriction
enzyme EcoRI
cuts the DNA
into fragments.
Sticky end
13–2
Manipulating DNA
3. Separating DNA
DNA plus
restriction
enzyme
Power
source
Longer
fragments
Mixture of
DNA
fragments
Shorter
fragments
Gel
Electrophoresis
13–2
Manipulating DNA
B. Using the DNA
Sequence
1. Reading the Sequence
2. Cutting and Pasting
3. Making Copies
13–2
B.
Manipulating DNA
Using the DNA Sequence
1. Reading the Sequence
2. Cutting and Pasting
3. Making Copies
Fluorescent
dye
Single strand
of DNA
Strand broken
after A
p324
Power
source
Strand broken
after C
Strand broken
after G
Strand broken
after T
Gel
13–2
B.
Manipulating DNA
Using the DNA Sequence DNA polymerase adds
complementary strand
1. Reading the Sequence
2. Cutting and Pasting
DNA heated to
3. Making Copies
separate strands
DNA fragment to
be copied
p325
PCR
cycles 1
DNA
copies 1
2
2
3
4
5 etc.
4
8
16 etc.
13–2
B.
Manipulating DNA
Using the DNA Sequence DNA polymerase adds
complementary strand
1. Reading the Sequence
2. Cutting and Pasting
DNA heated to
3. Making Copies
separate strands
DNA fragment to
be copied
p325
PCR
cycles 1
DNA
copies 1
2
2
3
4
5 etc.
4
8
16 etc.
13–3
Cell Transformation
Sneaking In
You probably have heard of computer
viruses. Once inside a computer, these
programs follow their original instructions
and override instructions already in the
host computer. Scientists use small
“packages” of DNA to sneak a new gene
into a cell, much as a computer virus
sneaks into a computer.
13–3
Cell Transformation
Sneaking In
1. Computer viruses enter a computer attached to
some other file. What are some ways that a file
can be added to a computer’s memory?
2. Why would a person download a virus
program?
3. If scientists want to get some DNA into a cell,
such as a bacterial cell, to what sort of molecule
might they attach the DNA?
CELL TRANSFORMATION
Essential Questions
•What happens during cell transformation?
•How can you tell if a transformation experiment has
been successful?
In 13.2 we talked about manipulating DNA
How do we get it back into the cell?
TRANSFORMATION- a cell takes in
DNA from outside the cell.
The DNA becomes part of the cell’s DNA
REMEMBER - Griffith’s experiment
TRANSFORMING BACTERIA
In 13.2 we talked about manipulating DNA.How do we get it back into the cell?
TRANSFORMATION- a cell takes in DNA from outside the cell.
That DNA becomes part of the cell’s DNA
REMEMBER - Griffith’s experiment
Transforming Bacteria
Foreign DNA attached to plasmid
Plasmid - small circular piece of natural DNA
•ensures DNA will be replicated
•contains genetic marker
such as resistance to antibiotic
(cells that survive antibiotic
Transforming Bacteria
Plasmid - circular piece of
bacterial DNA
Recombinant DNA just has to
be inserted into plasmid
Transforming Bacteria
Bacterial Transformation
Restriction
Enzymes:
Proteins that
cut the DNA in
a specific place
Recombinant
Plasmid
Bacterial Transformation
Bacterial Transformation
Section 13-3
Recombinant
DNA
Gene for human
growth hormone
Human Cell
o to
ction:
Sticky ends
Bacterial
chromosome
Plasmid
Gene for
human growth
hormone
Bacterial Transformation
Section 13-3
Recombinant
DNA
Gene for
human growth
hormone
Gene for human
growth hormone
Human Cell
Bacterial Cell
o to
ction:
Plasmid
Sticky ends
Bacterial
chromosome
DNA insertion
Bacterial cell for containing
gene for human growth
hormone
Transforming Bacteria
Foreign DNA attached to plasmid
Plasmid - small circular piece of natural DNA
•ensures DNA will be replicated •contains genetic marker
such as resistance to antibiotic (cells that survive antibiotic
have been transformed)
Transforming Plant Cells
In nature, bacteria insert plasmids into
plant cells and produce tumors
Researchers disable tumor producing gene
and introduce foreign DNA
Bacteria insert the foreign DNA into the plant
Transforming Plant Cells
In nature bacteria insert plasmid into plant cells that produces
tumors
Researchers disable tumor producing gene
and introduce foreign DNA
Bacteria insert the foreign DNA into the plant
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Sometimes possible to remove cell wall
and have plants take up DNA on their own
If transformation is successful, the
foreign DNA is integrated into one of
the host’s chromosomes.
If transformation is successful, the
foreign DNA is integrated into one of
the host’s chromosomes.
Transforming Animal Cells
Similar to plants
Sometimes possible to inject DNA into
egg cells
Usually contain marker gene
Recently developed techniques enable
genes to, “knock out” host gene
Transforming Animal Cells
Similar to plants
Sometimes possible to inject DNA into egg cells
Usually contain marker gene
Recently developed techniques enable genes to,
“knock out” host gene
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
13.4 Applications
of Genetic Engineering
•What are some examples of useful
transgenic organisms?
•What are the main steps involved in
cloning?
What are some examples of useful transgenic
organisms?
What are the main steps involved in cloning?
Applications of Genetic Engineering
In 13.2, we learned how DNA is
manipulated
In 13.3, we learned how foreign DNA
is inserted into host cells
Does this work between animals and
plants?
In 13.2, we learned how DNA is manipulated
In 13.3 we learned how foreign DNA is inserted into host cells
Does this work between animals and plants?
Transgenic Organisms
Contain genes from other organisms
Spurred growth of Biotechnology
Transgenic Microorganisms
Important products
•insulin •growth hormone
Human genes inserted into bacteria
Transgenic Microorganisms
Important products
•insulin •growth hormone
Human genes inserted into bacteria
Transgenic Animals
Mice given human genes to study
human immune system
Livestock given genes for extra growth
hormone
Poultry given genes to resist infection
Transgenic Animals
Mice given human genes to study human
immune system
Livestock given genes for extra growth hormone
Poultry given genes to resist infection
Transgenic Plants
Important part of food production NOW
•52% of soybeans •25%of corn in US
Built-in insecticides
Built-in weed control
A strain of rice with added vitamin A
13–4 Applications of
Genetic Engineering
Transgenic Organisms
Sometimes
DNA
directly
injected
QuickTime™
and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
“Knockout” genes
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.
Embryo
Cloned Lamb
The embryo develops
normally into a
lamb—Dolly
Go to
Section:
The embryo is placed in
the uterus of a foster
mother.
Foster
Mother
The
fused
cell
begins
dividing
normally
.
13–4 Applications of Genetic
Engineering: 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.
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 foster mother.
The embryo develops into a cloned animal.
13–4 Video: Clone Age
Copy these questions and use them to guide your
note taking during the video
1. What is a clone?
2. Give some examples of plants and animals that
have been cloned.
3. The video claims that there are human clones
walking among us. Explain how this could be
true.
4. Would a cloned human be the same as the
human he or she was cloned from? Explain