1. Bt Corn Genes from , e.g. European Corn Borer.
3.5.A3 Assessment of the potential risks and benefits associated with genetic modification of crops.
Bt Corn
Genes from , e.g. European Corn Borer.
Bacillus thuringiensis (Bt) is a
GM Foods by Bill Nye
Bt Corn FAQ by Colorado State University:
A hard look at GM crops by Nature:

2. Bt Corn General Potential Benefits:
3.5.A3 Assessment of the potential risks and benefits associated with genetic modification of crops.
Bt Corn
Genes from Bt have been inserted into maize so GM plants can produce an insecticidal toxin and therefore be resistant to pests, e.g. European Corn Borer.
Bacillus thuringiensis (Bt) is a soil bacterium that produces insecticidal toxins.
General Potential Benefits:
Introduction of a new trait – Bt gene increases resistance to pests such as the European Corn Borer
Results in increased productivity – less land used / greater yield / less crop damage
Less use of chemical pesticides – reduced cost / ecological damage to wild
Increased disease resistance
Less use of chemical herbicides
Less use of chemical fertilizer
Increased hardiness – better drought/cold/salinity tolerance and therefore can be grown in more locations / has a longer growing season
Increased nutritional content

3. Bt Corn General Potential Benefits:
3.5.A3 Assessment of the potential risks and benefits associated with genetic modification of crops.
Bt Corn
Genes from Bt have been inserted into maize so GM plants can produce an insecticidal toxin and therefore be resistant to pests, e.g. European Corn Borer.
Bacillus thuringiensis (Bt) is a soil bacterium that produces insecticidal toxins.
General Potential Benefits:
Introduction of a new trait – Bt gene increases resistance to pests such as the European Corn Borer
Results in increased productivity – less land used / greater yield / less crop damage
Less use of chemical pesticides – reduced cost / ecological damage to wild
Increased disease resistance
Less use of chemical herbicides
Less use of chemical fertilizer
Increased hardiness – better drought/cold/salinity tolerance and therefore can be grown in more locations / has a longer growing season
Increased nutritional content
Nature of science: Assessing risks associated with scientific research - scientists attempt to assess the risks associated with genetically modified crops or livestock. (4.8)
This point is implicitly dealt with in the Bt Corn case study.
Which benefits are relevant and need assessing for Bt Corn?

4. Bt Corn Potential Benefits:
3.5.A3 Assessment of the potential risks and benefits associated with genetic modification of crops.
Bt Corn
Genes from Bt have been inserted into maize so GM plants can produce an insecticidal toxin and therefore be resistant to pests, e.g. European Corn Borer.
Bacillus thuringiensis (Bt) is a soil bacterium that produces insecticidal toxins.
Bt was successfully introduced and Bt Corn is
Potential Benefits:
Introduction of a new trait – Bt gene increases resistance to pests such as the European Corn Borer
Results in increased productivity – less land used / greater yield / less crop damage
Less use of chemical pesticides – reduced cost / reduced ecological damage
Maximum productivity has not increased, but
Bt toxins are considered to be much more selective and than most conventional insecticides
Which benefits are relevant and need assessing for Bt Corn?

5. Bt Corn General Potential Risks:
3.5.A3 Assessment of the potential risks and benefits associated with genetic modification of crops.
Bt Corn
Genes from Bt have been inserted into maize so GM plants can produce an insecticidal toxin and therefore be resistant to pests, e.g. European Corn Borer.
All risks should be assessed as part of a comprehensive testing program.
Bacillus thuringiensis (Bt) is a soil bacterium that produces insecticidal toxins.
General Potential Risks:
Could be
Transferred genes could mutate after testing
by toxins
Increases evolves in pests
Accidental release may result in
Super weeds – through
– both plant populations by direct competition and animal populations directly and indirectly could be affected
Patent laws prevent farmers producing locally suitable varieties – this would lead to unregulated field tests, not a desirable situation

6. Bt Corn General Potential Risks:
3.5.A3 Assessment of the potential risks and benefits associated with genetic modification of crops.
Bt Corn
Genes from Bt have been inserted into maize so GM plants can produce an insecticidal toxin and therefore be resistant to pests, e.g. European Corn Borer.
General Potential Risks:
Could be toxic to or cause allergic reactions in humans
Transferred genes could mutate after testing
Non-target organisms affected by toxins
Increases resistance to toxin evolves in pests
Accidental release may result in competition with native plant species
Super weeds - through cross-breeding the introduced gene could be transferred to wild varieties
Biodiversity reduced – both plant populations by direct competition and animal populations directly and indirectly could be affected
Patent laws prevent farmers producing locally suitable varieties – this would lead to unregulated field tests, not a desirable situation
Bt toxin has been used for , however some experimental transgenic plants have caused allergic responses.
Bt is a very common soil bacterium – therefore organisms have been Negative affects on many non-target organisms …
… However many species of , and might be affected by Bt corn. [see 3.5.S3]

7. Bt Corn General Potential Risks:
3.5.A3 Assessment of the potential risks and benefits associated with genetic modification of crops.
Bt Corn
Genes from Bt have been inserted into maize so GM plants can produce an insecticidal toxin and therefore be resistant to pests, e.g. European Corn Borer.
General Potential Risks:
Could be toxic to or cause allergic reactions in humans
Transferred genes could mutate after testing
Non-target organisms affected by toxins
Increases resistance to toxin evolves in pests
Accidental release may result in competition with native plant species
Super weeds - through cross-breeding the introduced gene could be transferred to wild varieties
Biodiversity reduced – both plant populations by direct competition and animal populations directly and indirectly could be affected
Patent laws prevent farmers producing locally suitable varieties – this would lead to unregulated field tests, not a desirable situation
Unknown, but there is a risk
Risk is evolved from other transgenic crops
Ecosystem wide risks are unknown, but specific examples [see 3.5.S3] have been examined.

8. Bt Corn The caterpillar stage of the Monarch feeds on milkweed.
3.5.S3 Analysis of data on risks to monarch butterflies of Bt crops.
Bt Corn
Risks to monarch butterflies
The caterpillar stage of the Monarch feeds on milkweed.
Milkweed commonly grows on the edge of corn fields
Studies show some mortality in Monarch caterpillars fed milkweed leaves covered with Bt corn pollen

9. Bt Corn Risks to monarch butterflies
3.5.S3 Analysis of data on risks to monarch butterflies of Bt crops.
Bt Corn
Risks to monarch butterflies
To investigate the effect of pollen from Bt corn on Monarch larvae, the following procedure was used:
Leaves were collected from milkweed plants and lightly misted with water
A spatula of pollen was gently tapped over the leaves
The leaves were placed in water-filled tubes
Five three-day-old larvae were placed on each leaf.
Area of the leaf eaten was monitored over 4 days
Mass of larvae was measured after 4 days
Survival of larvae was monitored over 4 days
Three treatments were included in the experiment, with 5 repeats each:
Leaves not dusted with pollen (blue)
Leaves dusted with non-GM pollen (yellow)
Leaves dusted with pollen from Bt corn (red)

10. Bt Corn Risks to monarch butterflies
3.5.S3 Analysis of data on risks to monarch butterflies of Bt crops.
Bt Corn
Risks to monarch butterflies
Leaves not dusted with pollen (blue)
Leaves dusted with non-GM pollen (yellow)
Leaves dusted with pollen from Bt corn (red)

11. Bt Corn Analyze the data:
3.5.S3 Analysis of data on risks to monarch butterflies of Bt crops.
Bt Corn
Analyze the data:
Explain why non-GM corn was included in the study
Explain the need for replicates in experiments.
The bar chart and the graph show mean results and error bars. Explain how error bars help in the analysis and evaluation of data.
Explain the conclusions that can be drawn from the percentage survival of larvae in the three treatments.
Suggest reasons for the differences in leaf consumption between the three treatments.
Predict the mean mass of larvae that fed on leaves dusted with non-GM pollen.

12. Clone A group of . A group of .
3.5.U5 Clones are groups of genetically identical organisms, derived from a single original parent cell.
Clone
A group of
A group of
are naturally-occurring clones. So why do they appear different?
Epigenetics has the answer…
, if damaged, can regenerate a whole body from a single leg, another example of a natural clone.
So is , such as binary fission in bacteria.

13. Clone A group of genetically identical organisms.
3.5.U6 Many plant species and some animal species have natural methods of cloning.
Clone
A group of genetically identical organisms.
A group of cells derived from a single parent cell.
are modified laterally growing stems used to Each new plantlet can
Clones allow plants to quickly propagate (produce copies) successful plants.
, the swollen tips of underground stems, are storage organs in plants such as sweet potatoes. During winter the plant dies back, but in spring

14. 3.5.U7 Animals can be cloned at the embryo stage by breaking up the embryo into more than one group of cells.
Monozygotic twins
Embryos can split and then continue to develop separately to form identical twins.
This is possible because in embryonic development the cells are

15. can be achieved in the lab by .
3.5.U7 Animals can be cloned at the embryo stage by breaking up the embryo into more than one group of cells.
can be achieved in the lab by
Early embryo (cluster of identical cells)
Cells are separated
Each cell develops into an identical embryo
Each embryo is implanted into a different surrogate mother
Identical clone offspring are born

16. Investigating artificial propagation
3.5.S1 Design of an experiment to assess one factor affecting the rooting of stem-cuttings.
Investigating artificial propagation
Many common plants root easily from stem cuttings producing full-grown (clone) plants quickly.

17. Investigating artificial propagation
3.5.S1 Design of an experiment to assess one factor affecting the rooting of stem-cuttings.
Investigating artificial propagation
Examples of factors that can be investigated:
Substrate - water, type of soil
Number of leaves on the stem
Length of stem cut
Effectiveness of commercial rooting powders – hormones that stimulate root growth
Covering with a plastic bag (to reduce transpiration)
How the stem is cut
Proximity of a node (point of branching) to the base of the stem
Light – Intensity or duration (to simulate long days/short nights or short days/long nights)
Temperature

18. Investigating artificial propagation
3.5.S1 Design of an experiment to assess one factor affecting the rooting of stem-cuttings.
Investigating artificial propagation
Rigor of the design – things to consider:
Choose a plant species that forms roots readily in water or a solid medium
How will root growth/appearance be measured (you can expect multiple roots of variable length)?
Which variables need to be controlled?
What plant species/variety (or selection of) will be examined?
How many cuttings are needed to ensure a reliable investigation?

19. Cloning differentiated cells
3.5.U8 Methods have been developed for cloning adult animals using differentiated cells.
Cloning differentiated cells
To clone an organism with desired traits is problematic as a developed organism consists of specialized cells which are multipotent (can become one of several types of cells), unipotent (can become only one cell or tissue type) or cannot divide at all.
For a clone to develop, (diploid body) cells of the donor organism need to be to become (cells capable of dividing to become any type of cell).

20. Cloning differentiated cells
3.5.U8 Methods have been developed for cloning adult animals using differentiated cells.
Cloning differentiated cells
In 1958 John Gurdon of a (specialized diploid) (nucleus removed) frog egg.
In this way, he created tadpoles that were genetically identical to the one from which the intestinal cell was taken.
The method has been refined, but in essence remains the same. It is now termed

21. Cloning by somatic-cell nuclear transfer (SCNT)
3.5.A4 Production of cloned embryos produced by somatic-cell nuclear transfer.
Cloning by somatic-cell nuclear transfer (SCNT)
Creating a genetically identical organism through transfer of a differentiated diploid nucleus.
Dolly the sheep was the
Ian Wilmut cloned a sheep to produce Dolly in 1996

22. Cloning of Dolly with SCNT
3.5.A4 Production of cloned embryos produced by somatic-cell nuclear transfer.
Cloning by somatic-cell nuclear transfer (SCNT)
Creating a genetically identical organism through transfer of a differentiated diploid nucleus.
Cloning of Dolly with SCNT
Sheep cloned from a
Cell taken from and
taken from another sheep and ( nucleus removed)
Egg without nucleus is
Embryo resulting from fusion of udder cell and egg is
Surrogate mother gives birth to lamb – lamb is

24. The Process of Nuclear Transplantation (1:22)
Cloning Adult Animals (3:36)

25. SCNT and Therapeutic Cloning
3.5.A4 Production of cloned embryos produced by somatic-cell nuclear transfer.
SCNT and Therapeutic Cloning
is a technique used to do Reproductive Cloning, that is to make an
aims to develop cells that have not yet gone through the process of differentiation. This requires taking cells from an embryo and the cells used are known as

26. Therapeutic cloning made simple:
3.5.A4 Production of cloned embryos produced by somatic-cell nuclear transfer.
Therapeutic cloning made simple:
Remove a differentiated diploid nucleus from the cell to be cloned.
Enucleate a donor egg cell.
Insert the diploid nucleus into the enucleated egg cell.
Stimulate it to divide and grow in vitro.
The resulting embryo is a rich source of stem cells which can be harvested or cultured.
The inner cell mass is used to culture the tissues needed.
Nuclear transfer animation from HHMI:
Uses of therapeutic cloning:
Create stem cells for transplants, such as in burns patients or leukemia.
Replace other damaged tissues such as nerves, pancreas cells etc.
Much reduced risk of rejection of cells are they are genetically identical to the recipient.
A fibroblast is a cell in connective tissue that produces collagen and other fibers
How to obtain mouse embryonic fibroblast:
Creating stem cells animation from HHMI:

27. Make your own cloned mice and learn the process of cloning animal cells