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14 Δεκ 2012 (πριν από 4 χρόνια και 8 μήνες)

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Copyright © 2012 John Wiley & Sons, Inc. All rights reserved.

GENE TRANSFER AND
GENETIC ENGINEERING

CHAPTER 8


Copyright © 2012 John Wiley & Sons, Inc. All rights reserved.

Gene transfer


Vertical


DNA transfer to progeny




Lateral (horizontal)


Donation of DNA across the same generation


Copyright © 2012 John Wiley & Sons, Inc. All rights reserved.

Advantages of Genetic Diversity


Gene pools




Selective pressure




Evolution not extinction

Copyright © 2012 John Wiley & Sons, Inc. All rights reserved.

Transformation
-

History


Griffith (1920s)




Killed versus un
-
killed strains




“Transforming
principle”

Copyright © 2012 John Wiley & Sons, Inc. All rights reserved.

Transformation


Mechanism


Naked DNA
uptake





Significance


Recombinant
genotypes are
created


Copyright © 2012 John Wiley & Sons, Inc. All rights reserved.

Transduction


Mechanism


Viral particles carry
bacterial DNA from one
cell to another




Significance


Recombinant bacteria
with new genetic makeup
are created


Copyright © 2012 John Wiley & Sons, Inc. All rights reserved.

Conjugation


Mechanism


F plasmid directs pilus
formation between
bacteria


Duplicated plasmid
passes to second cell



Significance


Gene transmission
between bacterial cells


Common method of
antibiotic resistance
transfer


Copyright © 2012 John Wiley & Sons, Inc. All rights reserved.

Plasmid Types


F plasmid


Pilus formation genes



Resistance plasmids


Heavy metals


Antibiotics




Bacteriocin plasmids

Copyright © 2012 John Wiley & Sons, Inc. All rights reserved.

Plasmid Types


Virulence plasmids


C. tetani

neurotoxin


Salmonella


Tumor
-
inducing plasmids


Plasmid genes are transferred from
bacterium to plant tissue


Plant cell tumors make nutrients for
bacterial use


Plasmid encodes plant hormones


Plasmids conferring novel catabolism


Gasoline degradation


Nitrogen
-
containing compounds

Copyright © 2012 John Wiley & Sons, Inc. All rights reserved.

Protoplast Fusion


Cell wall removal with
genome fusions



Nocardia


Cephalomycin
antibiotic



Aspergillus



Yeasts

Copyright © 2012 John Wiley & Sons, Inc. All rights reserved.

Recombinant DNA Technology


Gene cloning




Restriction Endonucleases



DNA Ligase




Selection systems

Copyright © 2012 John Wiley & Sons, Inc. All rights reserved.

Recombinant DNA Applications


Medical


Humulin


Growth hormone


Industrial


Amylase for
S.
cerevisiae


Agricultural


N
2

fixation in non
-
legumes


Potatoes with insect
resistance





Copyright © 2012 John Wiley & Sons, Inc. All rights reserved.

Hybridomas


Monoclonal
Antibodies
(Mabs)



Diagnostics




Therapeutics

Copyright © 2012 John Wiley & Sons, Inc. All rights reserved.

Safety Issues


Safeguards and findings


ELSI


Environmental


Nutritional


“Emotionalism” ??


ASM statement



Concerns


Limited knowledge


Bioterrorism