Recombinant DNA: DNA from different
sources that would not normally be found
in biological organisms
Common "tools" used in
genetic engineering:
Restriction enzymes
(endonucleases, cut DNA),
DNA ligase ("glues" together
two pieces of DNA), reverse
transcriptase (retroviruses
[like HIV] produce reverse
transcriptase to copy their
RNA into DNA), plasmids
(circular self-replicating
molecules of DNA
Steps involved to genetically engineering
microbes to produce human proteins
1. Isolate cells that make the human
protein; 2. Isolate mRNA from they
cytoplasm of these cells; 3. Use
reverse transcriptase to make a DNA
copy of the mRNA; 4. Make this cDNA
double-stranded; 5. Assemble this
piece of DNA into a functional gene; 6.
Construct a "vector" to carry the DNA
into the host microbe; 7. Bacteria take
up plasmid + human gene; 8. Grow
large volumes of bacteria that have
this human "gene"; 9. Induce bacteria
to produce human protein; 10. Purify
the protein.
Genetically Engineered Plants
Herbicide resistance; pathogen
resistance; resistance to drought
or frost; increased shelf life;
improved nutrition; biofuel
production; useful by-product
production
Pros/Cons
Cost of seed & herbicide; growers
pay a "technology" fee and sign
agreements that they will not save
seeds from year to year; use of
more/less herbicides; transfer of
herbicide resistant genes to wild
relatives of crops potentially creating
'superweeds'
Terminator Plants:
seeds from the
transgenic plant do
not germinate;
value-added genes
PLUS terminator
gene complex
RIP genes
Saporin: a
ribosome
inhibiting
protein
Barnase: a
ribonuclease that
will eliminate
ribosome function
Traitor Plants: the
value-added genes are not
expressed unless a
particular chemical (an
inducer) is applied to the
crop. The inducer also
initiates the removal of the
value-added genes before
the second generation. Next
generation plants lack the
value-added genes.
Genetically Engineered Animals
Transgenic animals that
produce useful proteins in their
milk, eggs, or blood - "pharming"
Transgenic animals
that have improved
traits
Transgenic animals:
animals whose DNA
contains foreign genes