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Genetic engineering and biotechnology Topic 4.4

Genetic engineering and biotechnology Topic 4.4. Assessment statements 4.4.1 Outline the use of polymerase chain reaction (PCR) to copy and amplify minute

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  • Genetic engineering and biotechnologyTopic 4.4

  • Assessment statements4.4.1 Outline the use of polymerase chain reaction (PCR) to copy and amplify minute quantities of DNA.4.4.2 State that, in gel electrophoresis, fragments of DNA move in an electric field and are separated according to their size.4.4.3 State that gel electrophoresis of DNA is used in DNA profiling.4.4.4 Describe the application of DNA profiling to determine paternity and also in forensic investigations.4.4.5 Analyse DNA profiles to draw conclusions about paternity or forensic investigations.4.4.6 Outline three outcomes of the sequencing of the complete human genome.4.4.7 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.4.4.8 Outline a basic technique used for gene transfer involving plasmids, a host cell (bacterium, yeast or other cell), restriction enzymes (endonucleases) and DNA ligase.4.4.9 State two examples of the current uses of genetically modified crops or animals.4.4.10 Discuss the potential benefits and possible harmful effects of one example of genetic modification.4.4.11 Define clone.4.4.12 Outline a technique for cloning using differentiated animal cells.4.4.13 Discuss the ethical issues of therapeutic cloning in humans.

  • Polymerase chain reaction (PCR)Laboratory technique which takes a very small quantity of DNA and copies all the nucleic acids in it to make millions of copies of the DNAWay to ensure that enough DNA for analysis can be generated

  • Gel electrophoresisLaboratory technique used to separate fragments of DNA in an effort to identify its originEnzymes used to chop up DNA strands into fragmentsFragments are placed into small wells in the gelGel is exposed to an electric currentHeaviest, largest and least charged particles do not move easily through the gelSmallest, least massive and most charged particles pass through the gel to the other side easilyIntermediate particles are distributed in betweenIn the end, the fragments leave a banded pattern of DNA

  • DNA profilingProcess of matching an unknown sample of DNA with a known sample to see if they correspondReferred to as DNA fingerprintingIf, after separation by gel electrophoresis, the pattern of bands formed by two samples of DNA fragments are identical, it means that both came from the same individualIf the patterns are similar, it means that the two individuals are most probably related

  • Applications of DNA profilingPaternityMatch suspectsStudies of ecosystemsSocial relationshipsMigrating patternsNesting habitsCredibility to evolution

  • TOKHow would you feel if you were to find out from DNA profiling that your father was not your biological father?What effect would such a result have on the relationships between siblings or between spouses?What kind of emotions might someone feel after spending 18 years in prison, and then being freed thanks to a DNA test?

  • The Human Genome Project1990 2003Determined order of all the basesWorking now to decipher which sequences represent which genes and which genes do whatCan be useful in synthesizing beneficial molecules as medical treatment

  • TOKWhat does the sentence, We are all the same; we are all different, mean?Can one genetic group be considered genetically superior to another?What has our history taught us?http://www.blackgenocide.org/abortion.htmlWhy is abortion rates higher among African-Americans?http://www.blackgenocide.org/black.html

  • Gene transferTechnique of taking a gene out of one organism (donor) and placing it in another organism (host)Ex. host tomatoes more resistant to cold and frost due to donor DNA from a fishProteins used by fish to resist icy temp. of arctic waters are now produced by the modified tomato Would strict vegetarians be able to eat a tomato which has a fish gene in it?What happens to local ecosystems which rely on insects that may be killed by Bt crops?

  • Cutting and pasting DNAscissors made from enzymesRestriction enzymes called endonucleases find and recognize a specific sequence of base pairs along the DNA moleculeSets of four or six pairsGene is cut out and releasedCan then be removed from the donor organismDNA ligase pastes the genes to the sticky ends in a particular portion of the DNA sequence

  • Copying DNA (DNA cloning)Most of the genetic info for E. coli is in the single chromosomeSome DNA is found in plasmidsPlasmids are small circles of extra copies of DNA floating around inside the cells cytoplasmTo copy a gene, it must be glued into a plasmid

  • Steps of copying DNAPlasmid is removed from host cell and cut using a restriction endonucleaseGene to be copied is placed inside the open plasmid using DNA ligase (a.k.a. gene splicing)Recombinant plasmid is used as a vectorVector is placed inside host bacteriumBacterium allowed to grow and proliferateBacterium expresses the gene and synthesizes whatever protein the gene codes forUsed to make human insulin

  • Genetically modified organisms (GMOs)Organisms that has had an artificial genetic change Organisms produced to be more competitive in food production

  • Transgenic plantsUndesirable gene removedDesirable gene is put in its placeNew gene is just addedApplications:Delay ripeningTolerate high salinityProduce beta caroteneCould GM plants help solve world hunger?

  • Transgenic animalsUsed to produce a substance which can be used in medical treatmentExamples:Production of factor IX (protein needed for blood clotting) Resistance to parasitesPre-dyed woolShow dogsFaster racehorses

  • Benefits, promises, and hopes for the futureGM crops will help farmers by improving food productionFewer chemical pesticides will be neededProduction of rare proteins for medications could be less costlyGreater control over crop or livestock productionLower need for water

  • Harmful effects, dangers, and fearsEffect on ecosystemsGenes could cross speciesToxins to kill insects harmful to humansAllergiesFood supply property of small number of corporationsMay be simpler solutionsDecrease in biodiversity

  • Clones and cloningClone group of genetically identical organisms or a group of cells artificially derived from a single parentFertilized eggs do not differentiate until after dividing many timesIt was once thought that once differentiated, the cell could not be used to produce a cloneIn 1996, a sheep named Dolly was bornFirst clone whose genetic material did not originate from an egg cell

  • How Dolly was producedSomatic cell from donor sheep udder was collected and cultured; nucleus removedUnfertilized egg collected from another sheep; nucleus removedUsing a zap of electrical current, the egg cell and the nucleus from the cultured somatic cell were fused together

  • New cell developed in vitro and started to form an embryoEmbryo placed in the womb of a surrogate mother sheepEmbryo developed normallyDolly was born and presented as a clone of the original donor sheepKnown as reproductive cloning

  • Cloning using undifferentiated cellsTherapeutic cloning involves the copying of cells, not an entire individualAim is to develop cells which have not yet gone through differentiationInvolves embryonic stem cells

  • Ethical issues surrounding therapeutic cloningIs it ethically acceptable to generate a new human embryo for the sole purpose of medical research?Thanks to stem cell research may be able to:Grow skin to repair a serious burnGrow new heart muscleGrow new kidney tissue to rebuild a failing kidney