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 non-favorable 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-SIMILARindividuals

• 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

• 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!