Download Biotech & Genetic Engineering PP

Frontiers of Biotechnology
Manipulating DNA

Biotechnology is used to identify people, produce
transgenic organisms and clones, study diseases and
evolution, and create medical treatments for people with
life threatening diseases.
Techniques to Manipulate DNA

Scientists must be able to
work with DNA without
being able to see or handle
it directly.

Scientists use artificial
nucleotides, artificial genes,
chemical mutagens,
computers, enzymes,
bacteria, and many other
techniques to manipulate
DNA.
Spooled DNA
Restriction Enzymes

Restriction enzymes are enzymes that cut DNA molecules at specific
nucleotide sequences.


Any time the restriction enzyme comes across the specific nucleotide sequence, it
cuts the DNA.
This allows scientists to work with small pieces of DNA at a time.


Restriction enzymes are produced naturally by bacteria to cut the DNA of invading
viruses.
Restriction enzymes can either make clean cuts (blunt ends) of the DNA or
leave “sticky ends”

The “sticky ends” are staggered cuts in the DNA, that allow the DNA to reform
easily.
Restriction Maps

Gel Electrophoresis

Once DNA has been cut by
restriction enzymes, it is placed
into a gel electrophoresis plate.


Gel electrophoresis uses an electrical
current to separate a mixture of
DNA fragments from each other.
A positive electrode is set at one end,
and a negative electrode is set at the
opposite end.


Because DNA has a negative charge,
the fragments move toward the
positive end.
The larger fragments move slower
than the smaller fragments, therefore
the length of the DNA fragment can
be estimated by the distance it travels
through the gel in a certain period of
time.
Restriction Maps

Restriction maps use gel
electrophoresis to show
the lengths of DNA
fragments between
restriction sites in a
strand of DNA.

Restriction maps are used
to study mutations.


They will show if
nucleotides have been
added or deleted from a
particular strand of DNA.
Or, a mutation may lead to
a restriction site, and the
DNA would not be cut in
the same place.
Copying DNA



Forensic scientists use DNA from cells
in a single hair at a crime scene to
identify a criminal.
Doctor’s test a patient’s blood to
quickly detect the presence of bacteria
that causes Lyme disease.
Scientists compare DNA from
different species to determine how
closely the species are related.

If the original DNA from any of these
sources is too small to accurately study,
the samples of DNA must be increased,
or amplified, so that they can be
analyzed.
Polymerase Chain Reaction

PCR is a technique that produces millions—or even billions—of copies of
a specific DNA sequence in just a few hours.


It is a very simple process.
There are four materials involved: the DNA to be copied, DNA polymerases,
large amounts of each of the four nucleotides (A, T, C, G), and two primers.


A primer is a short segment of DNA that acts as the starting point for a new strand.
Each PCR cycle doubles the number of DNA copies. The original piece of DNA
becomes two copies. Those two copies become four…ect.
PCR Process
1. Separating.

The container with all the reactants is
heated to separate the doublestranded DNA into single strands.
2. Binding.

The container is cooled and the
primers bind to their complimentary
DNA sequences. One primer binds to
each DNA strand. The primers bind on
the opposite ends of the DNA
segment being copied.
3. Copying.

The container is heated again and the
polymerases begin to build new
strands of DNA. Added nucleotides
bind to the original DNA strands by
complimentary base pairing. The
polymerases continue attaching
nucleotides until the entire DNA
segment has been copied.
DNA Fingerprinting

DNA evidence is used to convict a criminal, release an
innocent person from prison, or solve a mystery.

A couple of decades ago, the lines and swirls of someone’s
fingertip were a detective’s best hope for identifying someone.
Now, investigators gather biological samples and analyze DNA
for another kind of evidence: a DNA fingerprint.
DNA Fingerprinting


A DNA fingerprint is a kind of
restriction map.
It is a representation of parts of an
individual’s DNA that can be used
to identify a person at a molecular
level.


People differ greatly in the number
of repeated non-coding sequences
of DNA.
DNA fingerprints can also be used
to show relationships between
family members.

The children have similar DNA
fingerprints to each other, but they
are not identical. Also, their DNA
fingerprints are combinations of the
DNA fingerprints of the parents.
DNA Fingerprinting and Identification

The reliability of DNA identification
relies on probability.

Ex. Suppose that 1 in every 500 people has
three copies of the repeat at location A.



That means that any person has a 1 in 500
chance of having a matching DNA fingerprint
for that region of their chromosome.
Then, suppose that 1 in 90 people has six
copies of the repeat sequence at location
B, and 1 in 120 people has ten copies of
the repeat sequence at location C.
Individual probabilities are multiplied by
each other to find total probability.
Therefore, when the three separate
probabilities are multiplied, suddenly the
chance that two people have the same
DNA fingerprint is very small.

1/500 x 1/90 x 1/120 = 1/5,400,000 = 1
chance in 5.4 million people.
Uses of DNA Fingerprinting

DNA fingerprinting can be used to
convict a criminal or set an
innocent person free.



The Innocence Project has
successfully released 249 wrongly
convicted people from jail using
DNA fingerprinting.
DNA fingerprinting can be used to
identify familial relationships
(paternity).
DNA fingerprinting is also used to
study biodiversity in an area,
identify genetically engineered
crops, and to follow migration
patterns of native species.
Larry Fuller spent 18 years in
prison, after being wrongfully
convicted of aggravated rape in
1981. Fuller was excluded as the
rapist after advanced DNA testing.
He was released in January 2007.
Genetic Engineering

Glowing mice are used in cancer
research, glowing plants are used to
track genetically modified crops,
and in 1999, British researchers
introduced glowing yeast cells.

The glowing yeast cells can detect
pollution in an environment.

Under normal conditions, the cells do
not glow, but when they come into
contact with certain chemicals, they
glow.

This indicated areas that need to be
cleaned up.
Cloning

A clone is a genetically identical copy of
a gene or of an organism.

Cloning can be a natural process.


Plants can clone themselves, bacteria produce
genetically identical copies of themselves, and
identical twins are clones of each other.
To clone a mammal, scientists swap
DNA between cells with a technique
called nuclear transfer.



1. An unfertilized egg is taken from an
animal, and the egg’s nucleus is removed.
2. The nucleus of a cell from the animal to
be cloned is implanted into the egg.
3. The egg is stimulated, and if the transfer
is successful, the egg will begin dividing.
Dolly: The First Clone

Born July 5th, 1996 in
Endinburgh, Scotland—was the
fist cloned mammal (cloned
from a mammary gland, and
named after Dolly Parton)


She was the only lamb who
survived to adulthood, out of 227
attempts.
She gave birth to 6 lambs, and
died at the age of 6 due to lung
disease.
The Future of Cloning

In January 2009, scientists in Spain
successfully cloned a Pyrenean Ibex—a
species declared extinct in 2000.



They used skin cells preserved in liquid
nitrogen.
The Ibex died shortly after birth due to
physical defects in its lungs.
The possibility of cloning other
endangered or extinct species (like the
wooly mammoth or dinosaurs) is closer.

This still does not increase genetic
diversity in breeding pools however, and
does not help loss of habitat.
Genetic Engineering

Genetic research relies on cloning,
but not of entire organisms.



Instead, the cloning of individual
genes is used to make a copy of
one segment of DNA.
In some cases, scientists insert
cloned genes from one organism
into an entirely different organism.
Genetic engineering is when you
change an organism’s DNA to give
an organism new traits.

Genetic engineering is only
possible because the genetic code
is shared by all organisms.
Recombinant DNA

Recombinant DNA is DNA that contains
genes from more than one organism.


To create recombinant DNA, scientists
often used plasmids located in bacteria.
 Plasmids are closed loops of DNA
within the bacteria that are easily
manipulated.
Scientists are using recombinant DNA to:




Try to create crop plants that produce
medicines and vitamins.
Try to create vaccines against HIV.
Make hormones like HGH, insulin, and
oxytocin.
Use in gene therapy.
 ETC!
Transgenic Organisms

A transgenic organism has one or more genes from
another organism inserted into the genome.

Ex. The gene for human insulin can be put into plasmids. The
plasmids are inserted into bacteria. The transgenic bacteria
make human insulin which can be collected and used to treat
people with diabetes.
Transgenic Plants

Scientists create transgenic plants
by inserting a gene into a bacteria’s
plasmid and having the bacteria
infect a plant. The infected plant will
then incorporate the new gene
into its DNA.


This technique has allowed
scientists to give plants new traits,
such as resistance to frost, diseases,
and insects.
 This increases crop yields, more
food is produced more quickly
and cheaply.
Genetically modified (GM) foods,
are now common in the United
States.
Transgenic Animals

Transgenic animals are difficult to make. It take many trials (hundreds)
before a transgenic animal will form correctly to adulthood.

The advantage with transgenic animals is that the transgenic gene will be present
in ALL of their DNA, including in their reproductive cell. So, transgenic traits will
be passed on to the next generation.
Transgenic mice are often used as models to study human development and
disease.
 They are used to study cancer (oncomice), diabetes, brain function and
development, sex determination, etc.

Other mice are called “gene knockout” mice.


These mice are used to student gene functions and point mutations.
Concerns About Genetic Engineering

There are concerns regarding human health and the
environment.

People routinely eat GM foods without knowing it. Scientists
have not been able to discover any adverse health effects so
far.

Critics claim that not enough research has been done on possible
allergic reactions or other unknown side effects.




Another concern is that GM plants may cause bees and butterflies to go
extinct (by transgenically producing pesticides).
Transgenic plants may also cross-pollinate with wild natural plants.
Finally, transgenic plants may decrease genetic diversity in crops and leave
them more vulnerable to new diseases or pests.
Another concern is about the ethics of genetic
engineering in the first place.
Genomics

Genomics is the study of genomes,
which can include the sequencing of
all of an organism’s DNA.



This is how we know that humans and
chimpanzees share 99-98% of their DNA.
Comparing DNA from many people at
one time helps researchers find genes
that cause disease, and it helps them
understand how medication works.
Biologists study DNA of different
species to learn how closely related
they are to each other and to
extrapolate how far back in the
evolutionary time line they diverged.
DNA Sequencing

All genomic studies begin with DNA sequencing.

This is determining the order of DNA nucleotides in genes or
in genomes.

PCR is one method.

Humans do not have the largest genome.Vanilla plants, crested newts, and
lungfish are among the many organisms who have a larger genome than us!
The Human Genome Project

There are 30,000-40,000 genes in the human
genome.


Each gene represents about 100,000 DNA
bases.
The Human Genome Project has two goals:
1. To map and sequence all of the DNA base pairs
of the human chromsomes.
2. To identify all of the genes within the sequence.
 Right now, the Human Genome Project is
working on the HapMap—the study of how
DNA sequences vary among people.
 This will hopefully identify genetic
differences that play a part in human
diseases.
Bioinformatics

Bioinformatics is the use of computer databases to
organize and analyze biological data.

Bioinformatics give scientists a way to store, share, and find
data.
Genetic Screening

Genetic screening is the process of testing DNA to
determine a person’s risk of having or passing on a
genetic disorder.


It often involved both pedigree analysis and DNA tests.
There are tests for about 900 genetic disorders, including
cystic fibrosis, Duchenne’s muscular dystrophy, and breast
cancer.
Gene Therapy

Gene therapy is the replacement of a
defective or missing gene, or addition
of a new gene, into a person’s genome
to treat a disease.


Scientists will often use de-natured
viruses to introduce the new gene to
the body.
 There have been a few successful
cases of gene therapy wiping out
diseases.
There are many experiments going on
with gene therapy.


Scientists are trying to insert genes into
the immune system that stimulated the
immune system to attack cancer cells.
Another method is to insert “suicide”
genes into cancer cells.