Chapter 15

Question 1

GMO vs Transgenic

Answer 1

GMOs are organisms whose genomes have been altered using genetic engineering technology
For an organism to be considered a GMO, the addition of DNA, hence the modified trait, should be able to be passed on to offspring
Transgenic organisms- genetic material from a different species is added

Question 2

Transgenic mice

Answer 2

Micro-injecting DNA into fertilised eggs
• Gene of interest is injected into a fertilised egg where male and female pronuclei have not yet fused
• Mouse pups screened and those that have the gene of interest are selected
Modifying embryonic-stem cells aim to silence/disable a gene (to find out its function)
• Defective DNA sequence injected into embryonic stem cell
• Replaces the functional gene through recombination

Question 3

Transgenic plants

Answer 3

Physical take-up of DNA
• DNA-coated gold particles accelerated into plant tissue using helium, once inside the cell DNA diffuses and integrates into the chromosomal DNA of the plant
• Enzymes can be used to remove the plant’s cell wall, placed in a solution with the foreign gene of interest, electroporation, take up of foreign DNA, placed in tissue culture and grown
Agrobacterium insert their Ti plasmid into plant cells, transfer of DNA segment, disease develops (manipulated to transfer foreign gene of interest instead)

Question 4

Examples of GMOs

Answer 4

Cotton
-cry1Ac gene from bacteria encodes a protein (Bt) that acts as an insecticide against leaf-feeding larvae (major pest)
Instead of using insecticides which are toxic to humans and wildlife, Bt is non-toxic and has to be ingested to take effect

Canola
-gox gene encodes enzyme that breaks down the active ingredient of a herbicide, harmful to other weeds and plants but harmless to canola

Tomato
Antisense mRNA which is complementary to the RNA transcription stops translation

RNA interference- dsRNA, cut into siRNA, combine with proteins, RNA-induced signalling complex breaks down complementary mRNA, protein silenced

Salmon

• growth hormone from the Chinook Salmon (largest of Pacific salmon)
• promoter gene from ocean pout which ensures GH is expressed continuously

BT cotton- produces BT toxin that specifically kills larvae, but don’t affect beetles or bees

Question 5

Advantages and disadvantages of GMOs

Answer 5

Productive
Efficient, greater crop yield, resistance to insects, tolerance to herbicides, tolerance for heat, cold, or drought

Affects food chain
irrevesible damage
may cause unkown diseases
Insects and weeds may become resistant 
Cross-contaminate other crops, gene flow between GMO and non-GMO crops, affects entire food supply