What is genetic

gooseliverBiotechnology

Oct 22, 2013 (3 years and 7 months ago)

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What is genetic
engineering?


Genetic engineering, also known as
recombinant DNA
technology
, means altering the genes in a living
organism to produce a
Genetically Modified Organism
(GMO)

with a new genotype.




blunt end





sticky end

Once the recognition site is found
Hae III
will
cleave the DNA at that site

These cuts produce

“blunt ends”

The names for restriction enzymes come from:



the type of bacteria in which the enzyme is found


the order in which the restriction enzyme was
identified and isolated.


Eco
RI

for example

R

strain of
E.co
li

bacteria

I

as it is was the first
E
.
coli
restriction enzyme to
be discovered.


Links

Other genetics links

14

Agrobacterium tumefaciens


Agrobacterium
tumefaciens causes
crown gall disease by
first transferring part of
its DNA into an opening
in the plant. The DNA
then integrates itself
into the plant's genome
and causes the formation
of the gall.

Genetic Engineering of
Animals and Food Crops

I.
Pharming definition

Use of animals/ plants as chemical factories to produce
commercial quantities of pharmaceutical products


(protein drugs only)

transfer human gene to animal/ plant and harvest protein
to use as a drug

II. Food Biotechnology

Background:




GM foods have been produced in the U.S. since the early
1990s.


The most common GM foods are soybeans, corn, canola,
and cotton.


As of 2006 in the U.S. 89% of soybeans, 83% of cotton
and 61% of corn was genetically modified.

II. Food Biotechnology

B. Engineering Herbicide Resistance: “Roundup™ Ready” crops


1.
Problem
:


Many herbicides are not selective for weeds only and therefore also kill off crop plants.


Roundup, a common herbicide, works by binding to and blocking an enzyme that is involved in
amino acid synthesis.


2.

Product
:

“Roundup™ Ready” corn, soybeans, cotton and canola


3.

Procedure
:

manipulate the plant so that it over expresses (produces more protein than it normally would) the
aroA gene, which codes for the enzyme that is blocked by Roundup.


4.

Result
:

Crop plants are resistant to treatment with Roundup, so it kills the weeds without causing them
harm.


An added benefit is that these crops requires decreased treatment with herbicides by 25%.


II. Food Biotechnology

C.
Engineering Insect Resistance: “Bt” crops


1.
Problem
:


Insects are common pests that kill many crops plants.


2.

Product
:


“Bt” corn, tomatoes and cotton



(Bt sprays have been used in the US since the 60s and are used in organic farming as a pesticide)


3.

Procedure
:



Insert the cryB gene from the bacteria Bacillus Thuringiensis (Bt) into the crop plants.



This gene produces a toxin that selectively kills only specific types of insects (the European corn
borer).


4.

Result
:


crop plants are resistant to insects that normally kill them.



An added benefit is that these crops require decreased treatment with insecticides.


II. Food Biotechnology

C.
Engineering Insect Resistance: “Bt” crops

4.
Result
:



crop plants are resistant to insects that normally kill them.



An added benefit is that these crops require decreased treatment with insecticides.


5. The
Starlink

controversy:



In 2000 Aventis used a different version of the cry transgene and transferred it into corn.



The use of this transgenic corn was limited to livestock feed/industrial use and NOT human food
consumption due to concerns over possible allergens in the corn.



Somehow the Starlink corn contaminated the food chain and was found in taco shells.

II. Food Biotechnology

D.
Engineering Frost Resistance: “Ice Minus” crops

1.
Problem
:


Many plants can not tolerate the formation of ice crystals and die or are damaged by frost.


2.
Product
:


“Ice Minus” Bacteria


3.
Procedure
:


Make a mutant form of this bacteria that lacks the protein that causes the ice crystals to form.



The mutant bacteria is then sprayed on crops.


4.
Result
:


Less frost damage to crops.

II. Food Biotechnology

E.
Engineering Fruit Ripening: “Flavr Savr” Tomatoes

1.
Problem
:


Fruits/vegetables taste better if allowed to ripen on the vine, but are more prone to rotting
during shipping and have a shorter shelf
-
life.


2.
Product
:


“Flavr Savr” Tomatoes (1985
-

the first genetically modified food!)


3.
Procedure
:


Make a tomato with a mutation in the gene that causes ripening. The result is a slow
ripening tomato.


4.
Result
:


Flavr Savr tomatoes could be vine
-
ripened, improving flavor, but did not rot quickly and
had a longer shelf life



This product was a good idea but was a flop! Society was not ready for GM foods and the
product was more fragile, requiring specialized shipping containers (which were expensive).


II. Food Biotechnology

F.
Engineering Nutritional Quality: “Golden Rice”

1.
Problem
:

Around 3 billion people eat rice as their staple food. Approximately 10% of this population is at
risk for Vitamin A deficiency (which can cause blindness) due to their poor diets.



2.
Product
:


“Golden Rice”


3.
Procedure
:


4 genes were inserted into rice, which created a biosynthetic pathway for Vitamin A, where it
did not exist before.



4.
Result
:


Golden Rice produced Vitamin A but not enough of it to solve the problem. A person would
need to eat 9kg a day of the rice to obtain enough Vitamin A in their diets. Scientists are still
working on this product.


What is genetic engineering


Various kinds of genetic modification are possible:


inserting a foreign gene from one species into
another, forming a
transgenic organism
;



altering an existing gene so that its product or
volume is changed



or changing gene expression so that it is it is not
translated
Knock out gene
.

Basic steps in genetic engineering

1.
Isolate the gene

2.
Insert it in a host using a vector (virus, plasmid, or
artificial chromosome)


Produce as many copies of the host as possible


Separate and purify the product of the gene


Transfer gene into target organism

Basic steps in genetic engineering


Recombinant DNA
-

Key component Genetic
engineering the DNA that results from gene
splicing.


Transgene
-

foreign DNA that is to be transferred
into a host


Vector
-

vehicle used to transfer the transgene to
host


gene gun


plasmid


virus