Transcript BIOTECHNOLOGY -intentional manipulation of

Do you agree or disagree with these statements:
1. I have eaten food that contains genetically modified
(GM) crops.
2. GM foods should be available, as long as they are
tested before they are sold for human consumption.
3. The risks of GM foods outweigh the possible benefits.
4. GM foods will help provide a sustainable food supply.
5. I am concerned about eating GM foods.
6. Farmers should grow corn that is genetically modified
to resist insects that damage cornfields.
• Genetically modified organisms
(GMOs) are organisms whose genes
have been directly manipulated by
scientists, often by inserting or deleting
one or more genes. Inserted genes are
typically from another species.
BIOTECHNOLOGY
-intentional manipulation of genetic material of an organism
•
• The only difference between living
organisms is the amount and order of
the four nucleotide bases of DNA.
Genome: the entire sequence of DNA
Gene: the part of the code that
corresponds to a protein
*genes can be transferred from one
organism to another*
BIOTECHNOLOGY
The intentional manipulation of genetic material of an organism
Why would we want to do this?
• To study cellular processes of an organism
– E.g. Glowing gene from jellyfish to tobacco plant
• To give one organism the trait(s) of another
– E.g. Anti-freeze from fish blood into
strawberries to survive through early frosts
• Should Canada allow farmers to grow
genetically modified food plants?
– Bt corn
– Terminator soya
Tools of Biotechnology
1. Plasmids: manipulating bacteria
Manipulating Bacteria:
The Making of a Plasmid
Plasmid:
- a small circular piece
of extra-chromosomal
bacterial DNA, able to
replicate
- bacteria exchange
these plasmids to share
DNA
- E.g. antibiotic
resistance genes
• Since plasmid is made of DNA it can code
for genes, ex. antibiotic resistance, and
can carry specific sequences of DNA
• Specific DNA
sequences can be
recognized by
enzymes called
restriction
endonucleases
Restriction Endonucleases/Restriction Enzymes
• enzymes that are
able to cut doublestranded DNA into
fragments at
specific recognition
sites in DNA
sequences
Ex. EcoRI:
5’-GAATTC-3’
3’-CTTAAG-5’
• Restriction enzymes can create “sticky ends
or “blunt ends”
Sticky Ends
• fragment end of a
DNA molecule with a
short single-stranded
overhang
Blunt Ends
• fragment end of a
DNA molecule with
no overhang
Once made, the ends can be re-joined together by
other enzymes ("enzyme glue")
To Make a Recombinant Plasmid:
Insert
1. Cut the plasmid and the
insert with the same
restriction endonuclease
to make complementary
sticky ends.
2. Combine the sticky ends
using ligase.
ligase: enzyme used to
join DNA together
3. Introduce the
recombinant plasmid into
bacteria.
Making a Recombinant Plasmid
Bacterial Transformation
• introduction of foreign DNA into a bacterial cell
• plasmid is used as a vector, a vehicle by which DNA
can be introduced into host cell
----
---+
+
- ++ - ++
-+ -+-+- +- -+
------
plasmid
+++++
phospholipid
bilayer
- ++ -++ Ca2+ ions
Following transformation bacteria are grown in
medium with antibiotic…
Only the bacteria that have the plasmid (and
therefore the antibiotic resistance) will survive.
Example plasmid:
Origin of Replication:
• where the plasmid starts to duplicate itself
• the specific sequence MUST NOT be cut by restriction
endonucleases or it won’t be able to replicate
Where do we get our insert sequence?
• From someone else’s DNA
– ex. fish gene in strawberries,
– jellyfish gene in plants
• Make it!
• In order to do these things, we need a way
to make many copies of the genes we want
Using Bacteria as Production Factories
•
•
•
•
easy to grow
no ethical issues
small genome
easy to manipulate
Making an insert:
Polymerase Chain Reaction
Common uses of biotechnology:
1. Making "stuff”
• proteins, enzymes, medication, etc. can be
produced by engineered bacteria!
• Food can be altered to have new traits
• Cloning (therapeutic and reproductive)
2. Genetic screening
• crime cases, relationship, genetic
screening, etc.
3. Gene Therapy
Therapeutic cloning
• used to produce tissue
that is identical to the
donor, to prevent
rejection
Reproductive Cloning
• creates an organism with the same
genetic material (DNA) as the
original organism – an EXACT
COPY of the donor
Dolly the Sheep
• the first cloned sheep
Ex. RFLP: Restriction Fragment Length
Polymorphism
Comparison of
different lengths
of DNA fragments
produced by
restriction
enzymes to
determine genetic
differences
between
individuals
Gene therapy
- desired gene is
inserted into cell's
nucleus using a
retrovirus as a carrier
- defective gene
replaced by functional
gene
Ex. ADA deficiency
- adenosine deaminase deficiency
- little immunity with low chances of recovery
- the T-cells of a four-year-old were
removed, modified and re-inserted to fix
her immune system