6.2 Genetic Engineering

6.2 Genetic Engineering

Genetic Engineering

Altering the sequence of
DNA molecules


Important in developing
drugs


Insulin


Human insulin produced by
bacteria



Somatropin

Genetic Engineering Pioneers


1970s
–

Stanley Cohen (plasmids) and
Herbert Boyer (restriction enzymes)


Experiments for selecting,

recombining and transforming

new genes into bacteria


Techniques are still used in

molecular biology labs


One of the most important discoveries in
biomedical research



1978
–

“
Genentech
”

biotechnology company
produced somatostatin


http://www.dls.ym.edu.tw/lesson/bacgen.files/10
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20.gif

Somatropin

A drug that is identical to
human growth hormone
(somatotropin)


Treats growth deficiency from
dwarfism and Turner
’
s syndrome


First human hormone produced
by genetic engineering


safe
and abundant production


Somatropin

production

Excise human growth
hormone gene using
restriction
endonucleases

Signal sequence is
removed

Insert gene after the
lac

promoter in a
plasmid transformed
into
E. coli

cells

E. coli

are grown in
media containing IPTG
(isopropyl
thiogalactoside)

Somatropin production (cont
’
d)

IPTG is an inducer of the
lac

promoter but is
not consumed by
E.coli

Control production of hormone


Presence of IPTG


somatropin production


Absence of IPTG

no

somatropin production

Somatropin is then isolated from bacteria and
sold to patients

lac
Z


lac
Y



lac
A

somatropin

RNA
polymerase

lac
I protein

IPTG

mRNA

Somatropin,
ß
-
galactosidase,
permease, transacetylase are
synthesized