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Genetic Engineering
Changing the world…
Why would we?
• Genetic Engineering, to engineer (or
make) genes, is a new and profitable
science that is as controversial as it is
amazing!
• To make or alter genes in any way, for the
benefit of humanity is a classic definition of
genetic engineering.
Hybrid Farming
Breeding Strategies
• One of the simplest and most profitable
type of genetic engineering is to
selectively breed.
• By selecting the most productive plants or
animals to produce the next generation,
people have found that the productivity of
domesticated species can gradually be
increased.
Dogs of All Sizes
Dogs of All Sizes
But where did dogs originate?
How did we get their genes to
start off?
Selective Breeding
• Selective breeding is simply selecting a
few individuals to serve as parents for your
next generation.
• This is not technically engineering new
genes, but it does alter that natural gene
flow
• By selectively altering the gene flow, we
can not only create favorable traits in
organisms, but it also can alter how often
the trait is observed.
Selective Breeding
• It is through selective breeding that we
have nearly all of the food items we
currently eat.
• Fruits, Meat, Flowers, Plants, Grass, if it
has different “types” it is like the product of
some form of breeding strategy (Most
often selective breeding)
Inbreeding
• Very often, inbreeding is the way
selective breeding starts.
• It is the easiest and fastest way to
selectively increase the likelihood of a trait
in offspring
• Inbreeding is when you cross organisms
with similar characteristics (often times the
organisms are closely related)
Inbreeding
• Dogs, as well as a multitude of other organisms,
are inbred to increase the likelihood of their
enjoyable traits.
• However, inbreeding has its risks. With an
increased chance of gaining favorable recessive
traits, you also increase your chance of nonfavorable traits.
• Remember, when a dominant and a recessive
trait cross, you only see the dominant… But
crossing the offspring of that organism, you have
a 1 in 4 chance of seeing a pure bread recessive
organism
Hybridization
• Hybridization is the crossing of NON-SIMILAR
individuals
• This usual involves crossing members of
different (but related) species
• The hybrids often contain favorable traits from
both parents and are hardier (this phenomena is
known as hybrid vigor)
• All commercial corn (as well as most crops) are
hybrids.
• Current corn crops make 10 times the corn!!!
Liger
Tigon
Making Ninja Turtles???
• We know that mutations are incredibly
dangerous, and 9 times out of 10 result in
death, so WHY is it that we spend millions
of dollars trying to force mutations?
• The problem with selective breeding is
that it is ALWAYS confined to genes that
are already found within a population
• Mutations, dangerous as they may be,
offer endless possibilty
Mutations
• If a breeder wants to try and get a new
trait into a population, but doesn’t want to
wait for the tides of time and chance to
give it, a mutation must be caused.
• Mutations can be caused by agents or
substances called mutagens.
• Mutagens (such as radiation or chemicals)
can occasionally cause favorable traits to
enter a population
Genetic Engineering
• In the last 2 decades molecular biologists
have developed a powerful new set of
techniques that affect DNA directly.
• For the first time biologists can engineer a
set of genetic changes directly into an
organisms DNA
• This new form of manipulation has now
taken on the term Genetic Engineering,
more so than selective breeding
Genetic Engineering
Genetic Engineering
• That was a picture of a tobacco plant that
has the chemical within a firefly in it.
– It has been engineered so that its cells can
produce the chemical.
Genetic Engineering Techniques
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Restriction Enzymes
DNA Recombination
DNA Insertion
DNA Sequencing
Transgenic Bacteria, Plants, and Animals
Cloning
Gel electrophoresis
Genetic Engineering Techniques
• Restriction Enzymes:
– Genes can be cut at specific DNA sequences by
proteins known as Restriction Enzymes
• (We know over 75 different restriction enzymes)
– Each recognizes and cuts DNA at a particular
sequence (area of Bases)
• They are INCREDIBLY accurate, they will ONLY
cut the area that they recognize
• This amazing ability allows us to cut DNA into
fragments so that we can isolate it, separate it,
and/or analyze it.
Genetic Engineering Techniques
• DNA RECOMBINANT:
– Literally means “combined DNA”
• DNA fragments cannot function all by
themselves.
• They must be part of the genetic material
of living things cells before the genes they
contain can be activated.
• In this, second step of genetic
engineering, the DNA fragment must be
put into a hosts cells
Genetic Engineering Techniques
• DNA RECOMBINANTS:
– An example, DNA fragments (cut by
restriction enzymes) may be combined with
bacterial DNA so that they can later be
inserted into a bacterial cell
– The small, circular DNA molecules in bacteria
(called plasmids) can be removed and cut
with a restriction enzyme.
– The cut ends are sticky to the foreign
fragment, and can allow for the formation of a
recombinant DNA molecule
Genetic Engineering Techniques
• DNA INSERTION:
– During the first 2 steps of genetic engineering, DNA
fragments containing the desired are obtained and
then inserted into DNA that has been removed from
the recipient cell (the cell where the DNA is going.)
• Forming recombinant DNA (New DNA)
– To insert the DNA into LIVING cells it is easiest to use
bacteria
• Bacteria in a solution of salt and the desired DNA will
eventually take up the DNA in its own DNA.
• These new bacteria are then cultured (grown) into a large
colony.
• The technical term for a large number of cells grown from a
single cells Clone. So this is DNA cloning.
• You don’t HAVE to use DNA but it is easiest.
Genetic Engineering Techniques
• DNA sequencing:
– Sequencing DNA is when you read the nitrogenous
bases (ATCG) along the length of the DNA fragment.
– Only one strand of the double helix is used to
sequence the DNA, but they do need multiples of the
used strand (So you clone it)
– The DNA is divided to 4 groups that undergo different
chemical treatments that break the pieces and reveal
the Base sequence.
– The pieces are separated by electrophoresis.
• (Page 323 Figure 13-6)
Electrophoresis
Gel electrophoresis
• During gel electrophoresis is cut with a
restriction enzyme into small pieces
• Because DNA has a slight negative
charge, different charges are placed at
either end of a gel containing tray.
• When the DNA is placed into the tray it will
slowly move across the gel (towards the +)
• Because the pieces are different sizes
they move at dif speeds.
Electrophoresis
DNA Fingerprinting
• The amazing complexity of the human
genome ensure that NO TWO
INDIVIDUALS are exactly the same.
• This biological “fact” (or more likely theory)
allows for a powerful new tool in criminal
investigations
• Now, finding bodily fluids and/or skin cells
at the scene of a crime or on a victim can
link a suspect to a crime with amazing
reliability.
Genetic Engineering Techniques
• Transgenic
– It is now possible to insert genes from one
organism into another.
– Organisms that contain such foreign genes
are said to be Transgenic.
– Trans- across or moved genes
Transgenic Organisms
• Transgenic Bacteria:
– When a gene coding for a human protein (like a
hormone or enzyme) is inserted into bacteria, the new
recombinant cells may produce LARGE amounts of
the protein.
– The human growth hormone, a hormone required for
growth and development, was incredibly rare before
genetic engineering.
– Now these transgenic bacteria (with the
corresponding foreign gene) are able to produce
enough growth hormone so that everyone who needs
it has all they need.
– Other proteins, like insulin (used in the treatment of
diabetes) and interferon (used to block viral growth
and battle cancer) are also made by transgenic
protein
What can we use this for?
Transgenic Organisms
• Transgenic Animals:
– DNA can be introduced into animal cells many
ways, including direct injection
– Growth hormones are used daily in many of
the cattle, fish, and poultry that we eat.
– We also use genetic engineering (DNA
Fragment Injection) to gain strains of AIDS
that we use to investigate the cure, further
research into the human immune system, and
many other medical researches.
Green Fluorescent Protein (GFP)
This transgenic animal is the result
of placing jellyfish genes in an
albino rabbit, and then bathing it in
UV light
Transgenic Organisms
CLONING
• In 1997 a Scottish scientist cloned a sheep
in which he named Dolly… since this time
we have cloned a multitude of organisms
(not including humans)
• To do this, the nucleus within an egg is
removed and replaced with the nucleus of
an adult cell.
• The cell is then placed into the
reproductive system a foster mother.
Making Dolly
Dolly’s life was cut short by cancer
only a few years following her
creation…
Cloning
Transgenic Plants
• It is through the process of genetic
engineering that we have most of the
plants that we use for food.
• Not only can we selectively breed more
productive organisms, but we can use
transgenic organisms to make plants that
are resistant to diseases, insects, drought,
winds, etc.
Human Genome
• Despite what many books may say we
HAVE actually mapped the ENTIRE
human genome.
• This was something that was originally
considered impossible, but as of 2003,
every transcribing base in the human DNA
strand is mapped, and at least to a
degree, understood
Genetic Engineering on Humans
• As we have discussed, there are multiple human
disorders that are treated by genetic
engineering.
• Everyday we advance further into the seemingly
limitless possibilities of genetic engineering.
• Regardless of whether or not genetic
engineering is ethically correct, it has amazing
scientific possibilities.
• Experimenting on humans ALWAYS has its
risks!