1. 3.5 Genetic modification and biotechnology
Applications:
Use of DNA profiling in paternity and forensic investigations
Gene transfer to bacteria with plasmids using restriction endonucleases and DNA ligase
Assessment of the potential risks and benefits associated with genetic modification of crops
Production of cloned embryos by someatic cell nuclear transfer
Understanding:
Gel electrophoresis is used to separate proteins of fragments of DNA according to size
PCR can be used to amplify small amounts of DNA
DNA profiling involves comparison of DNA
Genetic modification is carried out by gene transfer between species
Clones are groups of genetically identical organisms, derived from a single original parent cell
Many plant species and some animal species have natural methods of cloning
Animals can be cloned at the embryo stage by breaking up the embryo into more than one group of cells
Methods have been developed for cloning adult animals using differentiated cells
Skills:
Design of an experiment to assess one factor affecting the rooting of stem cuttings
Analysis of examples of DNA profiles
Analysis of data on risks to monarch butterflies of Bt crops
Nature of science:
Assessing risks associated with scientific research: scientists attempt to assess the risks associated with genetically modified crops or livestock

2. Polymerase Chain Reaction
Amplify small amounts of DNA
Just need a single molecule of DNA to make millions of copies
Able to study DNA without using up the whole sample
DNA from fossils
DNA from crime scene (hair, semen or blood)

3. PCR Answer these questions What are the ingredients for PCR?
What are primers?
Why must the mixture be heated/cooled to about 95°C? 55-60°C? 72°C?

4. Answers
1. Template DNA, DNA primers, Deoxynucleotide triphosphates, thermophilic polymerase with a buffer 2. Primers start the chain reaction = DNA strands separate as hydrogen bonds break = Primers bind to single DNA strands 75 = optimum temperature for DNA polyermase enzyme

5. Gel electrophoresis
Separate proteins according to size In an electric field Samples placed into wells in a gel Electrical field applied Charged molecules move through the gel Small fragments move faster than large ones

6. Gel Electrophoresis Activity
Go to:
Answer the following questions:
What is the gel made up of?
What is the purpose of the buffering solution that the gel is immersed in?
Why are known DNA fragment lengths/size standards needed?
How does the gel separate DNA strands of different lengths?

7. Powdered agarose, buffer (Jell-o)
Answers
Powdered agarose, buffer (Jell-o)
Salt water solution that allows electrical charges to move through the gel
Compare your bands to bands of known length to help you identify the length of DNA
DNA moves through gel repelled by negative charge – smaller moves further away

8. DNA profiling Sample of DNA obtained
Sequences selected and copied by PCR
Copied DNA split into fragments using enzymes
Fragments separated using gel electrophoresis
Produces a pattern of bands that is always the same with DNA from an individual
Compare profiles of individuals to see which bands are similar or different

9. Compare DNA at a crime scene with suspects DNA

10. Paternity tests Men claim they are not the father
Mother has multiple partners and isn’t sure
Child wishes to prove they are an heir

11. Genetic modification
Transfer of genes between species Genetic code is universal = amino acid sequences translated from genetic code is unchanged Same polypeptide is produced

12. Genetic modification Gene for making human insulin to bacteria
Goats produce milk that contains spider silk
Many GM crops

13. Salmon that grows twice as fast as normal

14. Contain vaccines for diseases
Vaccine bananas
Contain vaccines for diseases

15. Low methane cows
25% less methane – less impact on the environment

16. Involves the use of plasmids, DNA ligase and restriction endonucleases
Gene transfer
Involves the use of plasmids, DNA ligase and restriction endonucleases

19. Restriction endonuclease enzyme cuts DNA
DNA ligase fixes the strands together

21. Multiply bacteria containing gene

22. Separate and purify human insulin
Human insulin can then be used by diabetic patients

23. Enzyme also cuts bacterial DNA This produces a lot of insulin for human use Separate and purify insulin Insert insulin gene using DNA ligase Cut out insulin using restriction endonuclease Bacteria now contains insulin gene Locate the cell that contains insulin Multiply bacteria in a fermenter

24. 3. Enzyme also cuts bacterial DNA 7
3. Enzyme also cuts bacterial DNA 7. This produces a lot of insulin for human use 8. Separate and purify insulin 4. Insert insulin gene using DNA ligase 2. Cut out insulin using restriction endonuclease 5. Bacteria now contains insulin gene 1. Locate the cell that contains insulin 6. Multiply bacteria in a fermenter

25. Advantages and disadvantages (summarise page 192-194 all boxes!)
What is it
How is it done
What is it useful for
(Use examples)
Advantages and disadvantages (summarise page all boxes!)

26. Benefits Risks Environmental Health Agricultural
Fewer chemicals used and leaked into the environment
Less eutrophication
Out crossing of genes
Alter ecosystems
Affect food chains
If some plants are pesticide resistant – a lot of pesticides can be used then just to be sure pests are dead
Harm to other organisms
Health
Increase mineral/vitamin content
Decrease starvation (Sustainable way to feed the world)
Allergic reactions (do not know where a gene comes from)
Fewer nutrients
Ethical issues
Agricultural
Reduce pesticides (spend less money)
Increased yields
More aesthetically pleasing
Affect other organisms other than the target pests

27. Bt corn
Produces a toxin to protect them from corn pests Wind pollinated plant Pollen which also contains toxin blown away Monarch butterflies die

28. For or against
Many studies carried out Studies need to be carried out over large periods of time to see if there is a significant issue Many studies accused of being biased for/against GMOs GM good = GM companies GM bad = organic farmers

29. What is a clone?
A clone is genetically identical to its “parent” (single original parent)

30. Two types of reproduction
SEXUAL Genetically different offspring ASEXUAL Genetically identical offspring

31. Sexual Reproduction
HUMANS GAMETES Sperm cell: Egg cell: Each gamete contains 23 single chromosomes Half the number of that in a normal cell (23 pairs) These are haploid cells

32. Sexual Reproduction
FERTILISATION Gametes fuse together Form a cell with 23 pairs of chromosomes This is a Diploid cell
Offspring inherits features from both parents
Variation in offspring

33. Advantages SEXUAL REPRODUCTION
Variation in offspring means they are able to
Adapt to surroundings
Evolve

34. Asexual Reproduction
An ordinary cell can make a new cell by dividing in two New cell has exactly the same information as parent cell No fertilisation between male and female gametes Some plants and bacteria produce offspring asexually (some animals do too when no males around)

35. Advantages ASEXUAL REPRODUCTION Very quick
Bacteria can produce offspring in 20 mins
If already adapted to habitat – good to be identical

36. Cloning animal embryos
Break up embryo into more than one group of cells All cells in an early animal embryo are able to develop into any type of tissue

37. Cloning animal embryos
Sometimes this happens naturally Can also be done artificially Cannot tell whether the individual has the desired characteristics

38. Cloning Adults
Harder than cloning embryos as cells have already differentiated into different tissue cells

39. Dolly the sheep
Somatic-cell nuclear transfer 1. Adult cells taken from udder of Finn Dorset ewe and grown in the lab (udder contains some stem cells)

40. Dolly the sheep
2. Cells grown in a medium of nutrients Genes in the cells become inactive Pattern of differentiation was lost

41. Dolly the sheep
3. Unfertilised eggs taken from ovaries of a Scottish Blackface ewe Nuclei were removed from these eggs

42. Dolly the sheep
4. Electric pulse used to fuse the two cells together 10% of the fused cells develop into an embryo

43. Dolly the sheep
5. Emrbyos injected when around 7 days old into the uteri of surrogate mother ewes One out of 29 was successful = DOLLY! Who does Dolly look like?

44. Dolly the sheep
As it is the nucleus from a body cell of the Finn Dorset ewe Dolly is a clone of her.