Genetic engineering – recombinant DNA technology

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11 Δεκ 2012 (πριν από 4 χρόνια και 11 μήνες)

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Notes


Genetic eng
ineering


recombinant DNA technology

Biology


-

1

-

MD 032503


Genetic engineering


recombinant DNA technology







[BDL Ch. 13.2, p. 349
-
353 and zebra book, Ch. 11.2 & 11.3, p. 192
-
195]


Selective breeding

-

breeding of animals or plants to produce certain desired traits in the next
generation of offspring


Genetic engineering



the use of special biochemical techniques to identify, study or modify genes



Genetic engineers use a chemical process involving enzymes to transfer genes between
organisms
-

combining DNA from the genes of different organisms



Ex.


can biotechnically produce genetically engineered insulin



Genetic engineering can be a better alternative thatn selective breeding



Faster and more reliable method for increasing frequency of a specific allele in a population than
selective breeding



Some
techniques involve




Recombinant DNA



DNA with components from different organisms



Cut /
“cleave”

DNA and insert small fragments from one organism to another



Recombine DNA fragments from different sources



Take gene form one organism and transfer them into

another organism




Transgenic organism



organisms that contain foreign DNA



Organism with the inserted DNA will use the foreign DNA as its own




Example


transfer genes from humans into bacteria and then use bacteria to produce proteins
useful to humans



e.
g.


insulin and human growth hormone



bacterial cells reproduce quickly


this is an advantage



Sometimes transfer genes into yeast (unicelluar fungus) instead of bacteria since yeast is
eukaryotic and can and can translate DNA from other eukaryotes.









[Overhead


Recombinant DNA technique]



E.g


production of Hepititis B vaccine



e.g


insertion of genes into multi
-
cellular plants and animals, plants given chemicals to resist
weed
-
killing chemicals


3 steps

1.

isolate the foreign DNA fragment (
cleave

D
NA,
restriction enzyme
)

2.

attach the DNA fragment to a vehicle

3.

transfer of the vehicle into the host organism

Notes


Genetic eng
ineering


recombinant DNA technology

Biology


-

2

-

MD 032503





vector



carrier of genetic material



bacteria contains vectors called
plasmids



Plasmids



small circular pieces of DNA within bacteria



Use plasmid
s to move DNA into the cell



Can also use viruses to transfer DNA into cells




Restriction enzymes




[Overhead


Formation of Recombinant DNA]



1970s discovered DNA
-
cleaving enzymes



proteins that cut DNA at a specific series of base pairs / nucleotide sequen
ce



“cleave” (cut) the plasmid



cuts the DNA into fragments



results in fragments of different lengths



cleave both strands of the DNA at specific nucleotide sequences




restriction enzymes cut nucleotide sequences at
palindromes



palindrome



words or sentence
s that read the same forward or backward
-

ex. mom dad



same sequence on both strands of DNA, runnning in opposite direction

-
GAATTC
-













-
CTTAAG
-



a specific restriction enzyme cuts the DNA at specific locations



restriction enzyme EcoR1 cle
aves GAATTC between the G and A

--
G AATTC
--












--
CTTAA G
--



single
-
stranded sequences of DNA are left dangling at the ends of a fragment



there are hundreds of different restriction enzymes









BamH1 recognizes GGATCC, cuts betwn 2 Gs









Hind III recognizes AAGCTT, cuts betwn 2 As

Gene clonig



Clones



genetically identical copies



Each identical recombinent DNA molecules is a
clone



New DNA gets replicated inside the host


as if it were the host’s DNA







[Overhead


Cloning of Recombina
nt DNA in Bacteria]

Ex.
-

Human insulin production



Fragments then combined with another enzyme called
DNA ligase
, causing the gene for human
insulin to be inserted into the bacterial plasmid



A bacterium that contains the plasmid will produce human insulin



need large volumes of insulin


use billions of cloned cells to reproduce lare volumes of insulin


Notes


Genetic eng
ineering


recombinant DNA technology

Biology


-

3

-

MD 032503


Exercises:


Bioprobe

[zebra book p. 195]

#1
-
3



BDL Problem Solving Lab 13
-
2

[BDL p. 355]



BDL Section Assessment p. 356