Transcript The Good, the bad and the ugly of Genetic Engineering

The Good, the bad and the
ugly of Genetic Engineering
• Genetic engineering is the human
manipulation of the DNA code of
an organism in order to:
–Make transgenic organisms
–Clone an organism
–Perform Gene therapy
Transgenic Organisms
• Organisms which express a gene
from another organism
• Insert gene of interest into another
organism, receiving organism now
makes the protein from that gene
Practical applications
• Plants with “insecticide” genes
• Cows with extra copies of growth
hormones
• Insulin making bacteria
And most importantly…… (haha)
Practical applications?
• Cool Glow-in-the-dark Mice!!
Going back to the insulin made by
bacteria
• Diabetes: dysfunctional Insulin
gene; no or low amounts of insulin
protein made
– we can force bacteria to make
insulin for us
• Bacteria have circular pieces of DNA
called Plasmids
• They can replicate, transcribe and
translate any genes on the plasmid
• In plasmids there are also specific
sequences called restriction sites
restriction site
• Restriction enzymes recognize the
sites and cut the DNA at that site
• Each restriction enzyme recognizes
and cuts a different sequence
Examples:
Rest. Enzyme
Rest. Site
EcoRI
GAATTC
Hind III
AAGCTT
BamH1
GGATCC
Restriction enzymes recognize the
sites and cut one strand of the DNA
at that site
G AATTCGACTAGCGAT
GTGGATCGATCTTAA GCTGATCGCTA
CACCTAGCTA
• How many pieces do you get?
G
GAATTC
AATTC
GACTAGCGAT
GACTAGCGAT
GTGGATCGATCTTAAGCTGATCGCTA
GTGGATCGATCTTAA
GCTGATCGCTA
CACCTAGCTA CACCTAGCTA
• Single stranded ends are “sticky”
–Want to bind to complimentary bases
G
GTGGATCGATCTTAA
CACCTAGCTA
AATTCGACTAGCGAT
GCTGATCGCTA
• We can take advantage of this and
insert any gene we want into the
breaks
• Example: The Insulin gene
insulin
• What enzyme can we use to “seal
the gaps” between plasmid DNA and
insulin DNA?
insulin
Put plasmid back into bacteria (a
process called transformation)
Bacteria will transcribe and translate
our insulin gene even though the
insulin protein doesn’t do anything
for a bacterial cell.
Then we can take out the insulin
protein and use it to treat diabetics.
Same basic procedure, many
different transgenics!
• Giving cows extra copies of the
growth hormone gene
• Giving plants the gene that insects
have to ward off other enemy insects
• Giving mice the gene that jelly fish
use to fluoresce
Cloning
• Creating an
organism that
is genetically
identical to its
parent.
Cloning
• Mammals usually fuse info from
two parents (sexual reproduction)
• Cloning takes all the
chromosomes from 1 parent.
Sheep 1 Take 1 body
cell (udder)
Sheep 2
Take 1 egg
cell
Extract
Nucleus
Remove
nucleus
Inject
nucleus
into Egg
Zap to
stimulate
cell
division
Implant
embryo into
surrogate
sheep
(sheep 3)
Wait for Dolly to be
born
Which sheep is Dolly identical to??
Why?
Which sheep have to be female?
Snuppy
Human Genome project
What it did do: Tell us each an
every nucleotide of the human
genome (all 3.2 billion)
What it did not do: Tell us what it all
means!!!
Human Genome project
Now we have to break it down
and determine:
- which pieces are genes
- which pieces are junk
- what info the genes hold.
DNA finger printing
• Used to compare two people’s
DNA
• Used in paternity cases
• Used for crime scene analysis
DNA finger printing
DNA finger printing
• Based on the idea that
EVERYONE’s DNA is unique,
like a fingerprint
• BUT related individuals will have
more similarities
How to do a DNA fingerprint
• Get a sample of DNA and digest it
with restriction enzymes
How to do a DNA fingerprint
• If everyone’s DNA is unique, the
enzyme will cut each persons
DNA differently
• Example:
• TCATGAATTCATTGCCGAATTCCGTGAATCCAGAATTCGGACTA
• TCATGAAGTCATTGCCGAATTCCGTGAATCCAGACTTCGGACTA
How to do a DNA fingerprint
• Run cut up DNA on through
electrophoresis
• Click here for animation
How to do a DNA fingerprint
• Small pieces travel fast and move
further down the gel slab.
• Large pieces move slower and
stay closer to the injection point.
Gene Therapy
• Taking genetic testing one step
further
• Gene therapy tries to FIX the genetic
problem
How do we fix a gene?
Take a virus that
naturally
infects the
type of cells
that are
deffective.
How do we fix a gene?
Remove all the
virus’s DNA.
Replace it with
correct copy of
deffective
gene
Possibilities?
1. Cystic fibrosis
2. Hemophilia
3. Cancer