Genetic engineering - recombinant DNA technology

wirelessthrillBiotechnology

Dec 11, 2012 (4 years and 6 months ago)

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Notes



Genetic engineering


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 biot
echnically produce genetically engineered insulin



Genetic engineering
can be a better alternative tha
n selective
breeding




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



Notes



Genetic engineering


recombinant DNA technology

Biology


-

2

-

MD 032503


Recombinan
t DNA



DNA with components from different organisms



Cut /
“cleave”

DNA


-

insert small fragments from one organism to another




Take gene form one organism and tra
nsfer them into another





Recombine DNA fragments from different source
s


Transgenic organism



organisms that contain foreign DNA



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



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




e.g.


insulin and human gro
wth hormone



bacterial cells reproduce quickly


this is an advantage




Sometimes transfer genes into yeast (unicell
uar fungus)










[Overhead


Recombinant DNA technique]



E
xamples:



production of Hepititis B vaccine



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


3 steps

1.

isolate the foreign DNA fragment (
cleave

DNA,
restriction enzyme
)

2.

attach the DNA fragment to a vehicle

3.

transfer of the vehicle into the host organism




vector



carrie
r of genetic material



bacteria contains vectors called
plasmids



p
lasmids



small circular pieces of DNA within bacteria



u
se plasmids to move DNA into the cell



c
an also use vir
uses to transfer DNA into cells

Notes



Genetic engineering


recombinant DNA technology

Biology


-

3

-

MD 032503


Restriction enzymes



[Overhead


Formation of Re
combinant DNA]



1970s
-

discovered DNA
-
cleaving enzymes



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




“cleave”
(cut) the plasmid
,
cuts the DNA into fragments



results in fragments of different lengths



cleave both strands of
the DNA a
t specific nucleotide sequences



restriction enzymes cut nucleotide sequences at
palindromes



palindrome



words or sentences that read the same forward or
backward


ex.

mom



dad





same sequence on both strands of DNA, runnning i
n opposite
direction



-
GAATTC
-












-
CTTAAG
-




a specific restriction enzyme cuts the DNA at specific locations



restriction enzyme EcoR1 cleaves 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 diff
erent restriction enzymes





Ba
mH1 recognizes GGATCC, cuts betwee
n 2 Gs





Hind III recognizes AAGCTT, cuts betw
ee
n 2 As


Notes



Genetic engineering


recombinant DNA technology

Biology


-

4

-

MD 032503


Gene cloni
n
g



Clones



genetically identical copies



Each identical re
combinent DNA molecules is a
clone



New DNA gets replicated inside the host


as if it were the host’s DNA







[Overhead


Cloning of Recombinant DNA in Bacteria]


E
x
ample

-

h
uman 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



N
eed large volumes of insulin


use billions of cloned cells to
reproduce lar
g
e volumes of insulin