Download DNA

DNA Technology
Techniques in DNA technology
Restriction enzymes
 Gel electrophoresis
 PCR – polymerase chain reaction
 Recombinant DNA


SCI.9-12.B-4.9 - [Indicator] Exemplify ways that introduce new
genetic characteristics into an
organism or a population by applying
the principles of modern genetics.
 Chemical
treatments cause cells
and nuclei to burst
 The DNA is inherently sticky,
and can be pulled out of the
mixture
 This is called “spooling” DNA
DNA Extraction
“Spooled” DNA
Cutting DNA
 Restriction
enzymes cut
DNA at specific sequences
 Useful to divide DNA into
manageable fragments
Electrophoresis
 DNA
can be
separated based on
size and charge
 The phosphate
groups are
negatively charged
 DNA is placed in a
gel and electricity is
run through
 Negative
DNA moves toward
the positive end
 Smaller fragments move
farther and faster
Electrophoresis
Electrophoresis
Copying DNA
 Polymerase Chain Reaction
 Also called PCR
 A method of making many copies of
a piece of DNA
SCI.9-12.B-4.9 - [Indicator] - Exemplify
ways that introduce new genetic
characteristics into an organism or a
population by applying the principles of
modern genetics.
• A DNA molecule is placed in a small
test tube
• DNA polymerase that can work at
high temps is added
Steps in Copying DNA
Steps in Copying DNA
 The
DNA is heated to
separate the two
strands
 Primers, short pieces of
DNA complementary to
the ends of the
molecule to be copied,
are added
• The tube is cooled, and DNA
polymerase adds new bases to the
separated strands
Copying DNA
PCR
Large amounts of DNA can be made
from a small starting sample

Genetic Engineers
can alter the DNA
code of living
organisms.

Selective Breeding

Recombinant DNA

PCR

Gel Electrophoresis

Transgenic
Organisms
Genetic Engineering

Breed only those
plants or animals
with desirable
traits

People have been
using selective
breeding for
1000’s of years
with farm crops
and domesticated
animals.
Selective Breeding

The ability to
combine the DNA
of one organism
with the DNA of
another
organism.

Recombinant DNA
technology was
first used in the
1970’s with
bacteria.
Recombinant DNA
1.
Remove bacterial DNA
(plasmid).
2.
Cut the Bacterial DNA
with “restriction
enzymes”.
3.
Cut the DNA from another
organism with “restriction
enzymes”.
4.
Combine the cut pieces of
DNA together with
another enzyme and
insert them into bacteria.
5.
Reproduce the
recombinant bacteria.
6.
The foreign genes will be
expressed in the bacteria.
Recombinant Bacteria
1. Bacteria can make human insulin or
human growth hormone.
2. Bacteria can be engineered to “eat”
oil spills.
Benefits of Recombinant
Bacteria
The DNA of plants and animals
can also be altered.
PLANTS
1.
2.
3.
disease-resistant
and insectresistant crops
Hardier fruit
70-75% of food
in supermarket is
genetically
modified.
1.Create
recombinant
bacteria with
desired gene.
2. Allow the
bacteria to
“infect" the plant
cells.
3. Desired gene is
inserted into plant
chromosomes.
How to Create a Genetically
Modified Plant
What do you think about eating
genetically modified foods?
TRANSGENIC
ANIMALS
1.
Mice – used to study
human immune system
2.
Chickens – more
resistant to infections
3.
Cows – increase milk
supply and leaner meat
4.
Goats, sheep and pigs –
produce human proteins
in their milk
Genetically modified organisms
are called transgenic organisms.
Transgenic Goat
Human DNA
in a Goat Cell
.
This goat contains a human
gene that codes for a blood
clotting agent. The blood
clotting agent can be
harvested in the goat’s milk.
Desired DNA
is
added to an
egg cell.
How to Create a
Transgenic Animal
PCR
Polymerase chain reaction
This process makes millions of copies of
DNA to use in DNA fingerprinting. If a
single hair is found at a crime scene, there
is not enough DNA for fingerprinting. So,
you take the DNA from the hair, put it into
the PCR machine and you get lots of DNA
to run tests on.
Gel Electrophoresis
Gel electrophoresis is a commonly used
method of separating molecules based
on their charge, size, and shape. It is
especially useful in separating charged
molecules of DNA and RNA. [When an
electric current is applied to the gel,
negatively charged molecules move
toward the positive end, and positively
charged molecules move toward the
negative end.] The charge, size, and
shape of a particular molecule all affect
the rate at which a molecule moves
through the gel.
DNA Fingerprinting
1.
2.
You first must have enough
DNA to run a fingerprint.
PCR or polymerase chain
reaction is used to make
enough DNA.
The DNA is then cut with
restriction enzymes. The
more enzymes you use, the
more accurate the results.
3. After the DNA is cut into small
pieces, it is separated on a gel. The gel
is sometimes made of agarose. The
DNA is put into little holes in the gel
called wells.
4. The gel is put into a electrophoresis
chamber. A liquid buffer is poured
over the gel and the electricity is
turned on.
5. The electricity is turned on and the
DNA fragments separate from each
other. The largest fragments are too
heavy to be carried far and the
smallest fragments are carried closer
to the other end.
Is the other end positively or negatively
charged?