Recombinant DNA and Genetic Engineering

butterbeanscubaBiotechnology

Dec 12, 2012 (4 years and 7 months ago)

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Chapter 11


Genes are isolated, modified, and inserted
into an organism


Same or different organism



Made possible by Recombinant DNA
technology


Cut up DNA and recombine pieces



1. Get DNA and recombine it


Restriction enzymes



2. Copy it


Cloning


PCR



3. Analyze it


Sequencing


Molecular Fingerprinting



Plasmid: a small circle of
bacterial DNA



Foreign DNA inserted into
plasmid




Plasmid delivers DNA into
another cell


Used to Amplify a
specific region of
DNA.



Requires:


DNA as template



DNA polymerase



Cycles of heating
and cooling


Tandem Repeats


Short regions of DNA that differ substantially
among people



Many sites in genome where tandem
repeats occur



Each person carries a unique combination
of repeats


DNA is cut and then separated based on
size of the DNA


“Stained” and pattern of sizes is viewed


Identify or rule out criminal suspects


Identify bodies


Determine paternity



Transgenic
means?



Use bacterial
cloning vectors
to insert
foreign gene
(Ti plasmid)


foreign gene

in plasmid

plant cell

Resistant to herbicides Insect resistance



Genetically engineered
foods are widespread in
the US



Cut costs, reduce
herbicide and pesticide
use, enhance yields



What effect will they
have on humans?


Scientists transferred
daffodil genes into rice



Rice with beta
-
carotene may
help prevent vitamin A
deficiencies



Opponents fear unforeseen
consequences of creating
genetically modified
organisms


Terminator gene


Seeds from transgenic plants will be steril
e



Traitor gene


Seeds from transgenic plants require yearly
application of chemical to turn them “on” again


Produce medically valuable proteins


INSULIN!!!!



Breakdown environmental contaminants



Designed to survive only under narrow
conditions


Early experiments in mice


Injection of human growth
-
hormone gene
produced giant mice



“Knockout mice”


Study defective gene in mice instead of humans



Effects of transgenic animals seen in
agriculture, medicine, and industry.


Agriculture


Breeding and Quality


cows with more milk, sheep
with more wool, pig/cattle with more meat



Industry


Goats that make spider silk



Medicine


Goats


antithrombin


Rabbits


IL
-
2 for immune system


Cattle


collagen for skin grafts



Human organs are in
short supply


Pig organs are similar,
but human body rejects
them as foreign


Knockout pig genes that
trigger rejection


Can interspecies
transplants introduce
new diseases to humans?



Sequence all the
bases in human
DNA (3 billion!)


Finished in 2003


20,000 genes


Now what?


Even with the human genome fully
sequenced, it is still not easy to manipulate



Viruses used to insert genes into cultured
human cells



Very difficult to get modified genes to
work where and how they should


Retroviruses


Contain RNA that is injected
into host cell along with enzymes.


Reverse Transcriptase converts the RNA to DNA.


Integrase inserts the DNA into the host genome


Adenoviruses


Contains DNA that is put in
the host nucleus and transcribed.


Designed to cure “bubble babies”


Immune system can’t fight infection


Eugenic engineering


Selecting for “desirable” human traits



Creation of “designer” babies



Who should decide what genetic traits can
or should be altered?