REVISION: Topic 4.4 Genetic engineering and Biotechnology - PowerPoint Presentation

1. REVISION: Topic 4.4Genetic engineering and Biotechnology

2. Topic 4.4 –guideSTATE that, in gel electrophoresis, fragments of DNA move in an electric field and are separated according to their size.STATE that gel electrophoresis of DNA is used in DNA profiling.STATE that, when genes are transferred between species, the amino acid sequence of polypeptides translated from them is unchanged because the genetic code is universal.STATE two examples of the current uses of genetically modified crops or animals.DEFINE clone.---------------------------------------------------------------------------------------------------------------------------------OUTLINE the use of polymerase chain reaction (PCR) to copy and amplify minute quantities of DNA.DESCRIBE the application of DNA profiling to determine paternity and also in forensic investigations.ANALYSE DNA profiles to draw conclusions about paternity or forensic investigations.OUTLINE three outcomes of the sequencing of the complete human genome.OUTLINE a basic technique used for gene transfer involving plasmids, a host cell (bacterium, yeast or other cell), restriction enzymes (endonucleases) and DNA ligase.DISCUSS the potential benefits and possible harmful effects of one example of genetic modification.OUTLINE a technique for cloning using differentiated animal cells.DISCUSS the ethical issues of therapeutic cloning in humans.

3. Topic 4.4 –guideGel electrophoresisPCRDNA profilingGenetically modified cropsGene transferCloningHuman Genome Project

4. Topic 4.4 –guideGel electrophoresisPCRDNA profilingGenetically modified cropsGene transferCloningHuman Genome Project

5. Cutting and pastingWhat would you need for a cutting and pasting activity at school?gluescissorssomething to cutinstructions or a guide for what to dosomewhere to put it once it’s finished

6. Cutting and pasting – genetics style!What would you need for a cutting and pasting activity at school?DNA ligaserestriction enzymesbacterial plasmid or target genesticky endstarget or host cell

7. Gene transferOnly possible because genetic code is universalSTATE when genes are transferred between species, the amino acid sequence of polypeptides translated from them is unchanged because the genetic code is universal

8. Gene transferSteps: Plasmid removed from bacterial cellGene of interest removed from organism:restriction enzymes used to create sticky endsGene amplified with PCR (to get larger quantities of it)Gene of interest spliced into plasmidplasmid cut with same restriction enzymes as gene to create matching sticky endsglued together with DNA ligaseNewly made (=RECOMBINANT) plasmid inserted into host cellThe transgenic cells should express the new trait

9. Gene transfer

10. Gene transfer – question timeWhich enzymes are needed to produce recombinant plasmids to be used in gene transfer?Restriction enzyme and DNA ligase

11. Gene transfer – question timeState the name of a small circle of DNA, used for DNA transfer, in bacteria.DNA plasmid

12. Topic 4.4 –guideGel electrophoresisPCRDNA profilingGenetically modified cropsGene transferCloningHuman Genome Project

13. Genetically modified cropsMade using gene transferSTATE two examples of the current uses of genetically modified crops or animals

14. Genetically modified cropsExamples include:Bt corn produces a toxin (from Bacillus thuringiensis) that kills corn borerssheep that produce human blood clotting factor IX in their milksynthesis of beta-carotene in Golden RiceTM (vitamin A precursor so ups nutritional value)herbicide resistance in cropssalt tolerance in plantsdelayed ripening in Flavr-Savr™ tomatoesbacteria use to produce insulin and clotting factor VIII

15. Genetically modified cropsOften asked for benefits / dangers of genetic modificationBest to link them to an exampleYou should be able to list at least 3 advantages and disadvantagesAdvantages:- higher crop yields- less area needs to be farmed reduced pesticide use reduced costs, increased profits*** BE CAREFUL, LAST EXAM LIMITED BENEFITS TO THOSE FOR ORGANISMS (ie. no $)Disadvantages: may have unknown health effects (such as causing allergies)- toxin may kill other non-pest species by accident cross-pollination to weeds - reduced biodiversity

16. Topic 4.4 –guideGel electrophoresisPCRDNA profilingGenetically modified cropsGene transferCloningHuman Genome Project

17. PCR Polymerase Chain ReactionUseful for producing large quantities of a DNA sequenceUseful when only a small amount of DNA is available for testing (eg. crime scene samples, paternity testing kits)--------------------------------------------------------------------------------------------Steps: Heat DNA to separate the strandsAttach DNA primers to ends of the DNA sequenceUse DNA polymerase to copy the strands (like replication)Cool DNA to reform helix-----------------------------------------------------------------------------------------One PCR cycle  two identical copies of the DNAGenerally run 30 cycles  over a million copies

18. PCR

19. PCR – question timeWhich process is used in polymerase chain reaction (PCR)?Transcription, translation, replication or mutation?Replication

20. PCR – question timeIs PCR used for the preparation of a DNA profile?Yes!

21. Topic 4.4 –guideGel electrophoresisPCRDNA profilingGenetically modified cropsGene transferCloningHuman Genome Project

22. Gel electrophoresis & DNA profilingSTATE that gel electrophoresis of DNA is used in DNA profiling.

23. Gel electrophoresis & DNA profilingSTATE that, in gel electrophoresis, fragments of DNA move in an electric field and are separated according to their size.

24. Gel electrophoresis & DNA profilingUseful for separating DNA fragments to get a profile or identify an individual-------------------------------------------------------------------------------------Steps:All DNA to be compared cut with same restriction enzyme(s)Load into gel and apply an electric currentDNA moves towards the anode (+ve end)Fragments separate according to their size - small fragments move faster, separate further

25. Gel electrophoresis & DNA profiling

26. Gel electrophoresis & DNA profilingAll individuals generate unique fragment profiles.The bands/fragments will be a combination of your parents’ bands.Allows paternity/maternity testing to be undertaken.Allows crime scene DNA to be compared to both victim(s) and suspect(s).

27. Gel electrophoresis & DNA profilingClear identification of criminalsSuspect 1Suspect 2Sample from crime scene

28. Gel electrophoresis & DNA profilingClear identification of mothers, fathers, and siblings

29. Gel electrophoresis & DNA profilingAre they all related?Yes!Both children are related to both parents.

30. Topic 4.4 –guideGel electrophoresisPCRDNA profilingGenetically modified cropsGene transferCloningHuman Genome Project

31. CloningDEFINE: a group of genetically identical organisms

32. Cloning - annotate this diagramdonor eggnucleus removedenucleated donor eggelectrofusionegg allowed to develop into early embryo Embryo implanted into surrogate clone is bornorganism to be cloned(mammary) cell extracted

33. Cloning - annotate this diagramdifferentiated cell removed from animalsex cell removed from animalnucleus removed from unfertilized egg cellnucleus removed from differentiated animal cell

34. CloningReproductive cloning: cloning whole organismsTherapeutic cloning: using genetic technologies to produce organs, tissues and cells-------------------------------------------------------------------------------------

35. CloningThings to remember:Traits of donor and surrogate should be easily differentiated: Donor = Finn Dorset sheep = white Surrogate = Scottish blackface sheep = white with black face! Full set of chromosomes comes from donor. Whole nucleus is transferred not just half the genetic info. Ethics of cloning are debatable.

36. CloningOften asked for pros/ cons of therapeutic cloningYou should be able to list at least 3 pros and cons.Pros:– may cure serious diseases– may allow future discoveries – unwanted/unviable embryos can be used, as can donor adult tissues or umbilical cords– embryos have no nervous systems and can feel no painCons:– involves creation and destruction of human embryos– stem cell transplants may result in tumours– embryos “created” for research may be “killed” if in excess

37. Topic 4.4 –guideGel electrophoresisPCRDNA profilingGenetically modified cropsGene transferCloningHuman Genome Project

38. Human Genome ProjectComplete human genome (~25,000genes) known through international collaboration across 13-15years.Outcomes of completing the sequence of the human genome:Mapping (locating genes) – BRCA1 tests for breast cancerScreening (for disease) – full genome costs $1000 and takes 3 daysTreatment (gene therapy & targeted drug design) eg. new drugs based on DNA sequences of genes or the structure of proteins coded for by these genesAncestry (for understanding human origins & evolution)

39. Practice questionsThe diagram shows the cloning of the first sheep by Wilmut and Campbell in Scotland in 1997. What is Dolly’s DNA composition?A. The nuclear DNA is from the Finn Dorset and the mitochondrial DNA is from the Scottish Blackface. B. Half of the DNA is from the Finn Dorset and half is from the Scottish Blackface. C. All of the DNA is from the Scottish Blackface.D. All of the DNA is from the Finn Dorset.

40. Practice questionsUsing a named example, discuss the benefits and harmful effects of genetic modification. [9]May ‘09 SL P2 TZ1 – Data analysis

41. Practice questionsAnswers:A genetic modification is when the DNA/genotype of an organism is artificially changed;genetic modification alters some characteristic/phenotype of the organism;named example with modification (e.g. salt tolerance in tomato plants);benefits: [5 max]allows crops to be grown where they would not grow naturally;provides more food;economic benefits;expands world’s productive farmland;reduces the need to clear rainforests to grow crops;lowers cost of production;less pesticides/fertilizers/chemicals needed so better for environment;Award marks for any valid benefit consistent with a named example.harmful effects: [5 max]may be released into natural environment;may affect food chains / unintended effects on other organisms;may affect consumers e.g. allergies/health risks;unfair to smaller farmers who cannot compete;long-term effects are unknown;risk of cross-pollination;risk of long-term contamination of soil;Award marks for any harmful effect consistent with the named example. 9 max

42. Practice questionsAnswers:3. (a) (i) maize not modified/transformed with Bt (genes) / maize that did not have Bt gene added / not genetically modified / untreated maize 1 (ii) 50 – 12 = 38 (mm2); Accept 12 – 50 = –38 (38 ÷ 50) × 100 = (–)76%; (ECF) 2(b) there was a decrease in damage by all three types of stem borers compared to control; there was almost no change in damage by Eldana compared to control; there was almost no damage/little effect (to Bt maize type A) by Sesamia (and Eldana); Busseola caused the most damage (to Bt maize type A); 2 max(c) very efficient at controlling Sesamia; type B is the most effective against the three stem borers collectively; no type of Bt maize controlled Busseola well / vice versa , that is. Busseola not well controlled by any types of Bt maize; all types of Bt maize decreased Sesamia damage (significantly) / Bt maize type E not damaged by Sesamia / vice versa; Bt maize types C/H/I had more damage caused by Busseola (than was caused in the control) / vice versa; all types of Bt maize decreased Eldana damage (to some extent) / type B was not damaged by Eldana / vice versa; Eldana damage low in control / less effect; cannot determine efficiency since data is about leaf damage and stem borers may feed (preferentially) on other structures/stems/roots; 2 max

43. Practice questionsAnswers:3. (d) (268 – 215 =) 53 g (Accept answers in range 51–57 g. Units required. No workings required.) 1(e) mass increases in all three groups; increase is more rapid in beginning and tapers off later in the study; mass seems to be levelling off in rats fed Bt and non-Bt maize / rate of increase in mass is slowing down; rats fed rat food always have higher mass/greater mass increase than those fed either type of maize; 2 max(f) all three foods result in the same pattern of growth/mass gain / highest rate of growth at start of study / tapering off later in the study; Bt maize causes same amount of growth as non-Bt maize / appears to be as good a food source as non-Bt maize / there is no significant difference between Bt and non-Bt maize (in terms of mass gain); corn (both types) appears to cause less growth/mass gain than rat food / vice versa; genetic modification does not affect growth/mass gain; no evidence to support risk of Bt maize to growth/mass gain; study does not investigate other possible risks of Bt maize to rats; sample size is small / only 12 rats (in each group) so this may not be enough to give trends; only female rats tested, no males; 3 max [13]