Transcript GENETIC MODIFICATION and pGLO
GENETIC ENGINEERING
BIOLOGY 2/2A MOTZKO
Flavr Savr (1994) Combined tomato antisense (mutated) DNA to prevent the ripening process
GENETIC ENGINEERING
Recombinant DNA = utilizing DNA from two different sources
Transgenic DNA = utilizing DNA from two different species
Hence, all transgenic DNA is recombinant but not all recombinant DNA is transgenic
Fast Growing Salmon (2010)
Combines eel pout and salmon DNA to produce fish that grows 2x fast
A Cleaner Pig Sty (2012)
Combines E.coli, mouse and pig DNA to produce swine that produce 70% less phosphorus waste
And A Less Gassy Cow (2009)
Bioengineered cows produce 25% less methane gas as a byproduct of rumination
Venomous Cabbage (2002)
Combines scorpion and cabbage DNA to create vegetable that is poisonous to caterpillars but not to humans
A Banana A Day…
Banana saplings infected with virus carrying DNA codes for immunity to Hepatitis B. Vaccine then passed to humans via eating bananas
The Incredible,
Edible Egg (2007) Bioengineered British chickens lay eggs that contain monoclonal antibodies used to fight arthritis and multiple sclerosis
Evergreen (or not so green)
(2003) Colorado State bioengineers evergreens that change color when under attack from insects or when environmentally stressed.
Biosteel (2000)
University of Wyoming Study combines DNA of orb-weaving spiders with goats to produce large quantities of spider-silk in lactating females.
Fluorescent Feline Clones (2007)
South Korean experiment seeks to utilize bioluminescence to show that gene expression can be regulated. If so, felines could be created that express human diseases for research purposes.
WHAT?
A bacterial transformation Forcing a bacterial cell to transcribe and translate a sequence of foreign DNA into protein
WHY?
To create a transgenic organism (contains DNA from two different species) To show how genes are organized, controlled and expressed To demonstrate how artificial selection affects the evolution of a population
WHO?
Bacteria: Escherichia coli HB101
Source of Foreign DNA:
Aqueoria victoria
(naturally bioluminescent jellyfish)
Aequorea victoria
Why Escherichia coli?
Prokaryotic
No introns
Rapid growth
Non-pathogenic
HOW?
The jellyfish gene for bioluminescent protein (GFP) has already been spliced into a ring of DNA called a plasmid
E.coli forced to absorb these plasmids through a combination of chemicals and heat shock
Contents of pGLO Plasmid
Amp = gene coding for beta lactamase (makes E.coli HB101 resistant to the antibiotic ampicillin )
araC = gene coding for arabinase, an enzyme that allows E.coli HB101 to metabolize the sugar arabinose GFP = gene that codes for Green Fluorescent Protein
pGLO Operons
Beta Lactamase = codes for an enzyme that breaks down the antibiotic ampicillin Arabinase = codes for enzyme which helps hydrolyze the sugar substrate arabinose
How Do We Get The pGLO Plasmid Into E.coli HB101?
Four Testing Groups (Control & Independent Variables)
Four Test Groups Plates
1 LB (luria broth)
2 LB + Ampicillin (antibiotic)
1 LB + Ampicillin + Arabinose (sugar)
Contents of Each Vial
Vial 1 (for LB – and LB/amp-) gets 1 loop of bacteria, transformation solution but NO pGLO
Vial 2 (for LB/amp + and LB/amp/ara +) gets 1 loop of bacteria, transformation solution and pGLO
Transformation Solution
Bacterial plasma membrane will have its semi permeability altered through use of dilute CaCl 2 solution
Heat Shock
42 degrees C for 50 seconds, then back to ice
Luria Broth & Plating
Supply cells with Luria broth for recovery from stress After recovery, pour half of DNA – vial onto LB- and half onto LB/amp – Pour half of DNA + vial onto LB/amp+ and half onto LB/amp/ara+ plate
Incubation
Incubate at enteric (37 C) temperatures for 24-72 hours
HOW IS OUR GENOME A BUREAUCRACY?
Operon System
A series of structural and regulatory genes arranged in a manner such as to produce various proteins only when needed by the cell
A more efficient way to arrange and manage gene expression
Only 3-5% of genes need to be expressed at any given time
Operon Components
Promoter Region
= Place where RNA polymerase binds to DNA strand to start the transcription of genes into mRNA
Operator
: Location adjacent to promoter where repressor protein binds, blocking RNA polymerase from binding to the
promoter
Structural Genes promoter
region : The genes that are transcribed when RNA polymerase can bind to the
Repressor Gene
: codes for repressor protein to block the
operator
region
Inducible System
Inducible System: structural genes can only be transcribed when a specific substrate is present
Ex: Lactose operon (Jacob & Monod)
What Is Required To Induce Each Operon To Code For Its Protein?
Operon Function
When the substrate is absent, the repressor protein is produced and blocks access to the promoter of the operon When the substrate is present, the repressor is inhibited and the unblocked promoter can be accessed
If Function Dictates Form, How Can Recombinant DNA Be Expressed?
Antibiotic Selection Process
Not all bacteria will absorb the plasmids. We will kill off those that fail to absorb the plasmids by placing some of bacteria in environments containing the antibiotic ampicillin.
Those bacteria that survive must have picked up the pGLO plasmid because it contains the gene beta- lactamase, which destroys the antibiotic.
Inducing GFP Production
Not all the bacteria that have absorbed the pGLO plasmid will produce GFP.
To induce/force the bacteria to produce GFP, they must also be forced to produce the enzyme arabinase.
Why? Because the GFP gene was inserted into the plasmid adjacent to the arabinase gene.
If you “turn on” the arabinase gene, you will “turn on” the GFP gene by default.
Transformation Efficiency
Def: How many E. coli cells picked up the pGLO plasmid relative to the amount of pGLO plasmid to which they were exposed (expressed in trasnformants/µg)
Calculate transformation efficiency for LA+ and LAA+ plates (as they were the only ones exposed to plasmid)
Use pp. 43-48 in your pGLO manual