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

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SomatropinA 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

SomatropinproductionExcise human growth hormone gene using restriction endonucleasesSignal sequence is removedInsert gene after the lac promoter in a plasmid transformed into E. coli cellsE. 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.coliControl production of hormone Presence of IPTG somatropin production Absence of IPTGno somatropin production

Somatropin is then isolated from bacteria and sold to patients

lacZ lacY lacAsomatropin

RNA polymerase

lacI protein

IPTGmRNA

Somatropin, ß-galactosidase, permease, transacetylase are synthesized