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APPLIED GENETICS
Humans have been using the concept of
inheritance long before they understood
modern genetics. Now that we have a better
understanding we have gone quite a few
steps further.
Selective Breeding
Choosing the organisms with the most
desirable traits for mating. The only way
this is possible is if all organisms of the
same species are not the same.
Variation = inherited differences
For example:
Dairy cows. Joe-bob-jimbo the farmer wants cows that
produce enormous quantities of milk. He recognizes that
some cows, for whatever reason (but if they’re not
genetic reasons this won’t work) produce more milk than
others. Each breeding season he only breeds those cows
that produce lots of milk hoping their calves will inherit
their mom’s enormous milk-making abilities. Eventually,
Joe-bob-jimbo will have cows that produce mucho milk.
When the individuals chosen for mating are closely
related it’s called inbreeding
Hybridization:
This is mating two different
species together.
Sometimes this makes
for a hardier organism.
The classic example is
the mule. The mule is
stronger and more
durable than either the
horse or the donkey (the
parent species). The
problem is, due to
chromosomal
mismatching, most
hybrids are sterile.
Genetic Engineering:
This involves the actual
manipulation of genes
Step 1. Isolate the desired gene.
Step 2. Combine that gene with the new
organism’s DNA
Step 3. Insert the combined DNA into the
organism.
Recombinant DNA
Because a section of DNA is cut out of one
genome and the combined with another
genome it is referred to as:
RECOMBINANT DNA
Because the process is so similar to video and
audio tape splicing, this type of genetic
engineering is called Gene Splicing.
Biosteel
Genetic engineers in Plattsburg, NY have spliced the
gene for the protein that makes up spider’s silk into
goat zygotes (zygoats?).
Ounce per ounce, spider’s silk has more tensile
strength than steel.
When the spider’s gene is expressed in goats they
don’t spin webs and swing around the city fighting
crime (Spidergoat, spidergoat, does whatever a
spidergoat does)
Biosteel
Instead, the silk protein is secreted in the
milk of the goat. The goats are milked and
the protein separated from the rest of the
milk.
The protein is used instead of Kevlar in
bullet-proof vests and other applications
needing strength and flexibility.
Humulin
Some people lack a functional gene for insulin
Made in the pancreas, allows cells to take up glucose
Supplemental insulin was provided by taking
it from camels and sheep
That makes the sheep and
camels grumpy and dead.
Plus, some people were allergic or
sensitive to camel and sheep proteins.
Humulin
Enter E. coli
They’re a little bit easier to grow than goats
We splice the gene for human insulin from a human cell.
We turn the strand of DNA into a loop called a plasmid.
Bacteria are quite used to taking up plasmids into
their own genome so this is very easy.
Now we have a bacteria that can synthesis human insulin!
Makes for much happier camels!
Humulin on the Regents Exam