SBI 4U Genetic Engineering


11 Δεκ 2012 (πριν από 5 χρόνια και 7 μήνες)

237 εμφανίσεις

Genetic Engineering is the altering the sequence of DNA molecules

Many new products have been developed through genetic engineering, such as

There is also a huge agricultural impact.


Frost damage decreased by introducing bacteria that have b
een engineered
to disable the crops from “ice nucleation factor” (which is a protein that is
found on bacterial coats that allows ice to seed and crystallize)

The growth hormone: somatropin is being synthesized.


It is a drug that is identical to the hu
man growth hormone: somatotropin.


It is used to treat human growth deficiencies that results from a genetic
mutation that causes dwarfism and Turner’s Syndrome.


Because it helps build muscle, it is used to
help AIDS patients.


There has been some controve
rsy recently
around the availability of somatropin and
athletes. It is a banned substance in sporting
events during international competitions.


Another form of the drug: bovine
somatotropin is used in some states to boost
milk production in cows, but it

is banned in

The Polymerase Chain Reaction

Polymerase chain reaction: amplification of DNA sequence by repeated cycles of
strand separation and replication.

Before PCR, we could not make numerous copies of the one gene fragment unless
it wa
s inserted into a plasmid.

PCR is a direct method of making copies of a desired DNA sequence.

The process is very similar to DNA replication.


Instead of using DNA helicase and DNA
gyrase, PCR uses heat to unwind the DNA
because at high temperatures (94

C), the
hydrogen bonds break and the strands separate.


Next, the two single strands can be used to build
complementary strands


Then, in PCR, DNA primers are used because
they are easily produced in the lab (whereas in
replication, we need to put down

RNA primers


We copy the DNA strand by laying down the 5’ to 3’ (starting on the 3’
side of the original DNA)


One of the DNA primers is known as the forward primer, and the other is
the reverse primer because they make DNA in opposite directions.


The temperature is brought down to 50

C and it allows for the primers
to stick (anneal) onto the original strands.


Once the primers have annealed, the

(DNA polymerase
that can stand high temperatures) can now build the complementary


The cycle then repeats itself.


There is an exponential increase in the number of targeted DNA.

PCR is useful in forensic investigations, medical diagnosis, genetic research

Only requires a small amount of D
NA to work

Used to detect HIV earlier than normal

Used to determine if fossilized specimen were closely related species.

Restriction Fragment Length Polymorphism

Polymorphism: any difference in DNA sequence, coding or non
coding, that can
be detected b
etween individuals

All individuals from the same species are said to be polymorphic unless they are
identical twins.

Polymorphisms happen in both coding and non
coding regions.

In coding areas, polymorphisms may be used to
identify specific mutations:
for example, a person
who carries the allele for sickle cell anemia carries a
different allele for

globin that gives red blood cell a
sickle shape compared to a person who does not have
the disease.

We can have polymorphisms in our non
regions to
o, and are exploited in forensic

Restriction fragment length polymorphism
(RFLP) analysis

is a technique where DNA regions
are digested using restriction endonucleases and
subjected to radioactive complementary DNA probes
to compare the di
fferences in DNA fragment lengths
between individuals.


the patterns that result after running these cut
DNA’s through a gel are usually represented
by a big smear because there is so much DNA
available it doesn’t separate well.


so we have to a procedure t
hat allows the
DNA in an electrophoresis gel to be
transferred to a nylon membrane while
maintaining the position of the DNA band
fragments: called
Southern blotting

we denature the DNA so it becomes
stranded and the negatively
charged DNA will stic
k to the blotting
nylon membrane.

The membrane is then immersed in a
solution that has radioactive
complementary nucleotide probes for
specifically chosen areas on the DNA

Nylon membrane is then placed against
ray film and the radioactive probes cause ex
posure on the film,
to see a pattern.

p. 298 # 1, 3, 4, 5

p. 300 # 8, 9.