Chapter 8 – Gene Transfer & Genetic Engineering
Dr. Isaac M. Hagenbuch
University of South Carolina, Columbia
• Gene transfer significance
• Selective Breeding
- Plants
Shake pollen into flower
Wild Wheat: being cultivated by humans at 8,500BC
- then Einkorn wheat, then Emmer wheat, and now Bread Wheat at 1350BC
- Wild Wheat was thin, bread wheat is thicker (genetically engineered by selective
breeding)
• Animals
- Jacob sheep (2-6 horns)
Ancient breed
• Gene transfer: movement of genetic material between organisms
Multicellular eukaryotes: gene transfer involves sexual reproduction (vertical)
• Vertical: transfer genetic material to offspring
• Lateral: budding
- offspring are clones
- Handing off genetic info to individuals in same generation
Analogy: me being able to take genetic info from self that determine my own eye color, giving it
to you so you can display my eye color
• Recombination: Have to have donor and recipient
- when you have new genetic material that is brought in and becomes part of a
chromosome
- Recipient must place material in chromosome to become recombinant organism
• Donor
• Recipient
• Recombinant
Bananas: Big Mike banana
Can’t get in Western Hemisphere
- causes panama disease
In 1800’s everybody loved this banana
Plant top of tree again and some sprouts come off and you can plant those too
- clone (lateral)
SONG: Yes we have no bananas
Cavendish banana: what we eat
- doesn’t transport as well
- Doesn’t ripen as much
- Tree looks like the wilt (big mike banana AKA Fusarian)
- Fusarian fungus discovered in Taiwan, spreading south and west
• Tranformation
• A change in an organism’s characteristics due to transfer of genetic information.
, • First observed in 1928 by Frederick “Fred” Griffith.
Figure 8.1
• Observed non-virulent bacteria suddenly turn virulent.
Fred Griffith worked with bacteria that caused pneumonia
- working with mice trying to determine how to cure pneumonia
- Working with heat killing (rough and smooth)
- Smooth caused pneumonia, kill with heat, infect mouse, mouse is fine
- Rough strain cells, leave them alive, put in mice, mouse lives (no pneumonia)
- Put both in at same time, mouse dies, but find live smooth pneumococcus bacteria (you
put dead ones in)
Transformation!!!!
• And the change was heritable!
• It wasn’t until 1944 that this change was linked to DNA.
• Protein was long thought to be the carrier of genetic material.
• Transformation: How it Work?
• Some cells can/will uptake naked DNA from the environment under certain conditions.
Certain Conditions:
• High cell density, nutrient depletion.
- pH shock
- Exposure to UV light
• Competence factor: DNA binding protein
- protein that facilitates uptake of DNA
Take only one DNA strand, not both
• Not all species can do it (~67).
67 capable of doing this
• Most will take up DNA only from their own species.
• Limited information transfer.
- Foreign DNA chewed up
• Useful for repair.
- Smooth pneumococcus has capsule intact (original)
- Rough has one or more coating genes mutated
• Mainly a laboratory phenomenon.
• Transduction deduction
• Moving DNA between species via bacteriophage.
- two different form of lateral gene transfer
• Latin trans- “across” and –ductio “to pull”.
Head : capsid
Phage has DNA double stranded as it’s genome
• Virulent phage = Lytic Cycle
- When they bind their legs reel in and cause the body of virus to squat down onto
bacterium and the spiky butt plate contacts exterior of bacterium poking a whole. It
injects it’s chromosome this way.
• Temperate phage = Lysogenic Cycle.
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