Genetic Engineering


16 déc. 2012 (il y a 9 années et 1 mois)

463 vue(s)

Genetic Engineering

What is genetic engineering?


process of changing an
organism’s genetic material to
produce a new and useful result

results in a transgenic

(organism containing
recombinant DNA)

Tobacco Plant that
has had a firefly gene
inserted into its cells,
so it “glows”.

Why make transgenic plants
and animals?

Food production

Make plants that are resistant to pesticides and/or diseases


ready crops, crops resistant to certain viruses)

Engineer food to stay fresh longer and ripen at the store

Engineer some animals to grow larger without using antibiotics or
growth hormone.

Protein production

Cows and goats could produce human proteins in milk

Even plants can be used to produce human proteins

Vitamin A in “golden rice”

Medical Research

Use the “glow” gene to follow the expression of another gene.

Edible vaccines.

How does genetic engineering work?

The desired (“donor”) gene is isolated
from the organism’s DNA using a
restriction enzyme

Bacterial plasmid (“cloning vector”) is
cut with

restriction enzyme

Sticky ends of desired gene and plasmid should be

Ligase (an enzyme) is added to help seal
sticky ends of plasmid and desired gene

Last step: put the recombinant plasmid back
into the bacteria

Example: Insulin Production

Protein that codes for insulin production is
cut from human DNA using restriction
enzyme (EcoRI)

Example: Insulin Production

Plasmid (from
is also cut with EcoRI

Sticky ends are now
exposed on both
human DNA and
plasmid DNA

Example: Insulin Production

Ligase seals sticky ends
of desired DNA and
plasmid DNA

Recombinant DNA is
inserted into a

Bacterium divides,
producing 100’s of
bacteria with the
desired gene.

Why insert recombinant DNA into a bacterium?

Bacteria reproduce rapidly (some every
20 minutes)

Inserted gene (e.g. insulin) is copied
(cloned) whenever bacteria make a copy of
the plasmid

Results in a large amount of desired
protein (insulin) in just a few days

How can you insert recombinant DNA into
a host cell?


use electricity, heat,
or CaCl

to “shock”
cell into taking up


inject plasmid DNA
directly into cell
using microneedle

How can you insert recombinant DNA into
a host cell?

Gene gun:

tiny gold pellets
with recombinant
plasmid DNA and
“shoot” into cell

How can you insert recombinant DNA into
a host cell?

Viral vectors:

Desired gene is placed
into viral DNA and used to “infect” an
organism’s cells without causing disease
(virulence gene removed)