Genetic Engineering
Ch 15
“Real World Biology”
Ch 13-1 Changing the Living World
Selective Breeding
People select organisms with desired
characteristics to produce next generation
Takes advantage of naturally occurring
variation
Selective breeding of teosinte grass by
native Americans 6000 years ago led to
corn as we now know it
Selective Breeding
Hybridization
Cross dissimilar organisms
to bring together best of
both organisms
Ex: disease resistance +
increased yield
Benefits include hardier
plants
American botanist Luther
Burbank developed more
than 800 varieties of plants
using selective breeding
methods.
Selective Breeding
Inbreeding
Breeding a line of organisms with similar
characteristics
Ex: dog breeds
Risks- decreased genetic variation and
increased susceptibility for certain
diseases/disorders
Ex: hip dysplasia
Selective Breeding: Ligers
http://www.bing.com/videos/search?q=lige
rs&view=detail&mid=5F109EBB5D6E6243
677C5F109EBB5D6E6243677C&first=0&
FORM=NVPFVR&adlt=strict
Increasing Variation
Process used to
increase the variation
normally present in
nature
But why?
 Biotechnology is the
application of a technological
process, invention, or method
to living organisms.
Increasing variation
Can be accomplished through mutations
Mutations are usually random, but can be
induced via radiation and chemical
exposure
Potential to yield few beneficial mutants
with desirable characteristics not found in
original population
Increasing Variation
Bacteria- can treat millions at a time
increasing chances of producing useful
mutants
Ex: oil-digesting bacteria
Increasing Variation
Plants-arresting chromosome separation
during meiosis to produce polyploids
Known to be more vigorous than diploid
relatives
13-2 Manipulating DNA
Mutations are random
Having a way to alter DNA in a very
specific way to achieve a particular result
has huge advantages
Scientists can now use the knowledge of
DNA structure and its chemical properties
to study and change DNA molecules
Tools of Molecular Biologists
Genetic engineering allows biologists to
rewrite the DNA code of an organism
Modern techniques employed can
Extracting DNA from cells
Cutting it into smaller pieces
Identifying sequences of bases in DNA (genes)
Making unlimited copies
Finding Genes
Started with Douglas Prasher (1987)
Prasher wanted to find a specific gene in a jellyfish
that codes for a molecule called green fluorescent
protein, or GFP
• GFP is a natural protein that absorbs energy from light
and makes parts of the jellyfish glow
Prasher thought that GFP from the jellyfish could be
linked to a protein when it was being made in a cell
• bit like attaching a light bulb to that molecule
Finding Genes (GFP specifically)
Prasher compared part of the amino acid sequence of the
GFP protein to a genetic code table
 was able to predict a probable mRNA base sequence that would
code for this sequence of amino acids
Then used a complementary base sequence to “attract” an
mRNA that matched his prediction and would bind to that
sequence by base pairing.
 After screening a genetic “library” with thousands of different
mRNA sequences from the jellyfish, he found one that bound
perfectly
Finding Genes
To find the actual gene that produced GFP,
Prasher took a gel in which restriction
fragments from the jellyfish genome had been
separated and found that one of the fragments
bound tightly to the mRNA
That fragment contained the actual gene for GFP
This method is called Southern blotting, after its
inventor, Edwin Southern.
 These mice are glowing because scientists inserted a gene found in certain
bioluminescent jellyfish into their DNA. That gene is a recipe for a protein
that glows green when hit by blue or ultraviolet light. The protein is present
throughout their bodies. As a result, their skin, eyes and organs give off an
eerie light. Only their fur does not glow.
Finding Genes- Southern Blot
Analysis
Finding Genes
Today it is often quicker and less expensive for
scientists to search for genes in computer
databases where the complete genomes of
many organisms are available.
Richard Resnick: Welcome to the
Genomic Revolution
http://www.ted.com/talks/richard_resnick_
welcome_to_the_genomic_revolution.html
In this accessible talk from TEDxBoston,
Richard Resnick shows how cheap and
fast genome sequencing is about to turn
health care (and insurance, and politics)
upside down.
Copying DNA (specific genes)
 First step is a polymerase chain reaction (PCR)
 Heat a piece of DNA
• separates its two strands
 DNA cools and added primers bind to the single strands
 DNA polymerase starts copying the region between the
primers
• These copies can serve as templates to make still more
copies.
Polymerase Chain Reaction
Once biologists find
a gene, a technique
known as
polymerase chain
reaction (PCR)
allows them to make
many copies of it.
1. A piece of DNA is
heated, which
separates its two
strands.
Polymerase Chain Reaction
2. At each end of the
original piece of DNA, a
biologist adds a short
piece of DNA that
complements a portion
of the sequence.
 These short pieces are
known as primers
because they prepare, or
prime, a place for DNA
polymerase to start
working.
Polymerase Chain Reaction
3. DNA polymerase
copies the region
between the primers.
These copies then serve
as templates to make
more copies.
4. In this way, just a few
dozen cycles of
replication can produce
billions of copies of the
DNA between the
primers.
Copying DNA
It is relatively easy to extract DNA from cells
and tissues.
 The extracted DNA can be cut into fragments
of manageable size using restriction enzymes.
 These restriction fragments can then be
separated according to size, using gel
electrophoresis or another similar technique
Gel Electrophoresis
http://learn.genetics.utah.edu/content/labs/
gel/http://learn.genetics.utah.edu/content/l
abs/gel/
http://learn.genetics.utah.edu/content/labs/gel/
Recombinant DNA Technology
It is a form of genetic engineering that cleaves
DNA into small fragments and inserts those
fragments into a host organism
Host may be the same or a different species
Transgenic Organisms
Organisms who have incorporated foreign
DNA in their chromosomes and use this
new DNA as their own
Mr. Green Genes
http://www.youtube.com/watch?v=k_Z6M3
mDt9Q&safe=active
How to Produce a Transgenic Organism
Step 1: Isolate the gene in the foreign
DNA that you want to insert
Ex: isolate the gene for beta carotene in a
daffodil so you can then add it to rice
Step 2: Cut it out of the chromosome (in
daffodil) using restriction enzymes.
Restriction enzymes are bacterial
proteins that have the ability to cut both
strands of the DNA molecule at a specific
nucleotide sequence
Resulting fragments can have blunt ends
or sticky ends
In biology, sticky end and blunt end are the two possible configurations resulting from
the breaking of double-stranded DNA. DNA exhibits a stabilizing interaction between
complementary base pairs, providing specificity to the pairing of two strands of DNA. If
two complementary strands of DNA are of equal length, then they will terminate in a
blunt end, as in the following example:
5'-CpTpGpApTpCpTpGpApCpTpGpApTpGpCpGpTpApTpGpCpTpApGpT-3'
3'-GpApCpTpApGpApCpTpGpApCpTpApCpGpCpApTpApCpGpApTpCpA-5'
However, if one strand extends beyond the complementary region, then the DNA is
said to possess an overhang:
5'-ApTpCpTpGpApCpT-3'
3'-TpApGpApCpTpGpApCpTpApCpG-5'
If another DNA fragment exists with a complementary overhang, then these two
overhangs will tend to associate with each other and each strand is said to possess a
sticky end:
5'-ApTpCpTpGpApCpT
pGpApTpGpCpGpTpApTpGpCpT-3'
3'-TpApGpApCpTpGpApCpTpApCpGp
CpApTpApCpGpA-5'
becomes
5'-ApTpCpTpGpApCpT pGpApTpGpCpGpTpApTpGpCpT-3'
3'-TpApGpApCpTpGpApCpTpApCpGp CpApTpApCpGpA-5'
Some Commonly used REs
EcoRI (eco r one)
HindIII (hindi three)
BamHI (bam h one)
TaqI (tack one)
Step 3: Cut host’s DNA with the same RE
so cut ends will match up
When DNA from two different organisms
joins up- recombinant DNA is formed
Vectors
Getting DNA from one organism into
another requires a vector
The vector introduces the new DNA into the
host cell
Bacterial DNA is often used as a vector
Bacterial DNA
Bacteria contains plasmids- small rings of
DNA separate from the bacterium’s larger
circular chromosome
The foreign DNA is inserted into the
plasmid by cleaving both using the same
restriction enzyme
Sticky ends match up and foreign DNA
becomes part of plasmid
Gene Cloning
Plasmid with foreign DNA (Now
considered recombined DNA) is inserted
into a bacterial cell
Plasmids can replicate within the cell and
can produce up to 500 copies in the cell
Soon Tons of Copies!
Bacteria clones the recombinant DNA
Clones-genetically identical copies
How?
Bacterial cells themselves will reproduce
quickly, each with hundreds of copies of
the recombinant DNA inside (plasmid +
foreign DNA)
Introduction into Host Cell
Plasmid is then inserted into a host’s
chromosome where it will be replicated
each time the cell replicates along with the
organism’s other chromosomes
The host cell can transcribe/translate that
recombinant DNA into protein just like all
other proteins coded in its DNA
Cloned Coyotes
http://www.youtube.com/watch?v=x0EGgy
mKh3A&safe=active
 South Korean scientist Hwang Woo-Suk (L) and Vasily Vasiliev (R),
vice director of North-Eastern Federal University of Russia's Sakha
Republic, exchange agreements during a signing ceremony on joint
research at Hwang's office in Seoul. The research collaboration
agreement will help Russian and S.Korean scientists to recreate a
woolly mammoth which last walked the earth some 10,000 years
ago
Should we clone Neanderthals???
A U.S. scientists says we are now capable
of cloning a Neanderthal baby by
introducing Neanderthal genome material
into a human stem cell and implanting it
into a surrogate mother. The theory is,
cloning a Neanderthal would increase
human diversity and show us new ways of
thinking or even curing disease.
But what of the moral and legal issues?

Ellen Jorgensen: Biohacking -- You
can do it too
http://www.ted.com/talks/ellen_jorgensen_
biohacking_you_can_do_it_too.html
We have personal computing, why not
personal biotech? That’s the question
biologist Ellen Jorgensen and her
colleagues asked themselves before
opening Genspace, a nonprofit DIYbio lab
in Brooklyn devoted to citizen science,
where amateurs can go and tinker with
biotechnology.