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IB Biology 3.5 genetic modifcation and biotechnology

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IB Biology 2015 Curriculum Genetics 3.5

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IB Biology 3.5 genetic modifcation and biotechnology

  1. 1. 3.5 Genetic modification and biotechnology Essential idea: Biologists have developed techniques for artificial manipulation of DNA, cells and organisms. http://www.nacentralohio.com/wp-content/uploads/2013/01/WW_0113_GMO_AppleOrange.jpg
  2. 2. Understandings Statement Guidance 3.5 U.1 Gel electrophoresis is used to separate proteins or fragments of DNA according to size 3.5 U.2 PCR can be used to amplify small amounts of DNA. 3.5 U.3 DNA profiling involves comparison of DNA. 3.5 U.4 Genetic modification is carried out by gene transfer between species. 3.5 U.5 Clones are groups of genetically identical organisms, derived from a single original parent cell. 3.5 U.6 Many plant species and some animal species have natural methods of cloning. 3.5 U.7 Animals can be cloned at the embryo stage by breaking up the embryo into more than one group of cells. 3.5 U.8 Methods have been developed for cloning adult animals using differentiated cells.
  3. 3. Applications and Skills Statement Guidance 3.5 A1 Use of DNA profiling in paternity and forensic investigations. 3.5 A2 Gene transfer to bacteria using plasmids makes use of restriction endonucleases and DNA ligase. 3.5 A3 Assessment of the potential risks and benefits associated with genetic modification of crops. 3.5 A4 Production of cloned embryos produced by somatic-cell nuclear transfer. [Dolly can be used as an example of somatic-cell transfer.] 3.5 S1 Design of an experiment to assess one factor affecting the rooting of stem-cuttings. [A plant species should be chosen for rooting experiments that forms roots readily in water or a solid medium.] 3.5 S2 Analysis of examples of DNA profiles. [Students should be able to deduce whether or not a man could be the father of a child from the pattern of bands on a DNA profile.] 3.5 S3 Analysis of data on risks to monarch butterflies of Bt crops.
  4. 4. 3.5 U1 Gel electrophoresis is used to separate proteins or fragments of DNA according to size Visualizing DNA Sequences • Enzymes are used to cut DNA into fragments of various lengths. • These fragments are placed into small wells at one end of the gel in a gel box filled with a buffer (which conducts a current). • The electrical current running through the box has a positive on one side and negative side (DNA is negative and attracted to the positive). • The fragments of DNA will move through the gel based on size and charge. • The smallest particles that are charged go the farthest in the gel, while the large non- charged particles fall out and embed in the gel the quickest.
  5. 5. 3.5 U1 Gel electrophoresis is used to separate proteins or fragments of DNA according to size
  6. 6. 3.5 U1 Gel electrophoresis is used to separate proteins or fragments of DNA according to size
  7. 7. • Genetic screening is the testing of an individual for the presence or absence of a particular gene. There are many potential uses of genetic screening. • The purpose may be to identify disease carriers. e.g. Carriers of Cystic Fibrosis or PKU • The purpose may be to inform the treatment of a disease e.g. HLA- 27b associated with types of Arthritis (not causal). 3.5 U1 Gel electrophoresis is used to separate proteins or fragments of DNA according to size http://www.dls.ym.edu.tw/ol_b iology2/ultranet/Chromo7.gif
  8. 8. Advantages and of genetic screening • Early Diagnosis of diseases therefore reducing the accumulation of the damaging effects of some diseases eg. PKU/ Guthrie test • Screening of parents who may be carriers of alleles that may cause the diseases. In this way the frequency of the disease can be reduced in the population • Reducing the frequency of the allele through controlled IVF for embryos not carrying the allele 3.5 U1 Gel electrophoresis is used to separate proteins or fragments of DNA according to size http://media2.wcpo.com/photo/2014/08/06/wcpo- baby_1407374007598_7250945_ver1.0_640_480.jpg
  9. 9. 3.5 U2 PCR can be used to amplify small amounts of DNA. • PCR (polymerase chain reaction) is a laboratory technique that takes a single or few copies of DNA and amplifies them to generate millions or more copies of a particular DNA sequence. • When you collect DNA from different sources such as sperm samples or small drops of blood, there are usually very little usable cells to collect DNA. • Therefore, PCR is used to create enough DNA to be analyzed for investigations such as forensics or custody cases. • Once large quantities of the DNA have been created, other methods such as gel electrophoresis are used to analyze the DNA. Click4Biology
  10. 10. 3.5 U2 PCR can be used to amplify small amounts of DNA. • For analysis of dead organisms (wooly mammoth). • To make more copies of DNA found at crime scenes. • From a single embryonic cell for prenatal diagnosis
  11. 11. 3.5 A.1 Use of DNA profiling in paternity and forensic investigations. 1. The first step in identifying an unknown child is to first match the bands (size and location) from the mother that appear in the child. A good way to do this is to mark the child with the same color as the mother for the bands that match or to put a small M next to the matching bands. 2. The next step is to match the remaining bands with one of the unknown samples from the different father possibilities. As 50% of the DNA inherited in the child will come from the mother and 50% of the DNA will come from the father, the remaining bands should match with the unknown father’s sample. 3. Once again, colors can be used to match the child’s remaining bands to the correct father’s bands or by using other notation such as F3 to mark the matching bands. 4. A similar technique can be used in criminal investigations using the victim’s blood and the possible suspect’s blood to match an unknown sample found at a crime scene http://www.atdbio.com/img/articles/STR-analysis-parentage-large.png
  12. 12. 3.5 A.1 Use of DNA profiling in paternity and forensic investigations.
  13. 13. Case 7286224: The Green Street Holigans 3.5 A.1 Use of DNA profiling in paternity and forensic investigations.
  14. 14. DNA Profile Results: Case 7286224 3.5 A.1 Use of DNA profiling in paternity and forensic investigations.
  15. 15. DNA Profile Results: Case 7286224 3.5 A.1 Use of DNA profiling in paternity and forensic investigations.
  16. 16. A Paternity Case: is he the father? 3.5 S.2 Analysis of examples of DNA profiles. [Students should be able to deduce whether or not a man could be the father of a child from the pattern of bands on a DNA profile.]
  17. 17. Sample Question:
  18. 18. Sample Exam Question: Answer
  19. 19. Genetically Modified Organism (GMO)Plant Examples: Golden Rice enriched with beta-carotene which converts into vitamin A 3.5 U.3 Assessment of the potential risks and benefits associated with genetic modification of crops. http://upload.wikimedia.org/wikipedia /commons/2/29/Golden_Rice.jpg
  20. 20. Potential benefit 1. Higher yields 2. Less land need to grow 3. Less pesticides sprayed 4. Could add genes for certain proteins, vitamins or possible vaccines 5. Crops last longer or don’t spoil during storage 6. Can use pest resistant crops or modified crops in areas where water availability is limited 7. Varieties of crops lacking certain allergens or toxins Potential harm 1. Long term effects on humans are unknown 2. Animals may be harmed for Bt 3. Cross-pollination could occur with wild species giving them a competitive advantage. This could allow these plants to outcompete and eliminate other plants (decrease biodiversity). 4. Some people or livestock might have allergic reactions to certain proteins produced by transferred genes 3.5 U.3 Assessment of the potential risks and benefits associated with genetic modification of crops.
  21. 21. 3.5 U.3 Assessment of the potential risks and benefits associated with genetic modification of crops. Benefits and risks of Genetic Transfer (GMO) •Example Maize crop can be damaged by corn borer insects. A gene from a bacterium has been transferred to maize. The gene codes for a bacterial protein called Bt toxin that kills the corn borers
  22. 22. • Gene cloning: process by which scientists can product multiple copies of specific segments of DNA that they can then work with in the lab Tools of Genetic Engineering • Restriction enzymes used to cut strands of DNA at specific locations (restriction sites) – Restriction Fragments have at least 1 sticky end (single- stranded end) • DNA ligase: joins DNA fragments • Cloning vector: carries the DNA sequence to be cloned (eg. bacterial plasmid) 3.5 U.4 Genetic modification is carried out by gene transfer between species.
  23. 23. • Usually a virus (bacteriophage) or a bacterial plasmid. • A plasmid is a small, circular piece of DNA. • The virus will insert the gene on its own. • A plasmid will be taken up in bacteria through transformation. 3.5 U.4 Genetic modification is carried out by gene transfer between species.
  24. 24. 3.5 U.4 Genetic modification is carried out by gene transfer between species. Vector: Bacteriophage is a virus that infects bacteria.
  25. 25. Gene Transfer (gene cloning) 3.5 A.2 Gene transfer to bacteria using plasmids makes use of restriction endonucleases and DNA ligase.
  26. 26. 3.5 U.4 Genetic modification is carried out by gene transfer between species. • A gene produces a certain polypeptide in an organism. • Since the genetic code is universal, when a gene is removed from one species and transferred to another the sequence of amino acids in the polypeptide produced remains unchanged. • Gene modification has been used to introduce new characteristics to certain animal species. For example goats that produce milk containing spider silk and bacteria that produce human insulin. A plant example is the production of golden rice that contains beta-carotene .
  27. 27. Gene Transfer in Insulin Production: 3.5 U.4 Genetic modification is carried out by gene transfer between species.
  28. 28. 3.5 U.4 Genetic modification is carried out by gene transfer between species.
  29. 29. 3.5 S.3 Analysis of data on risks to monarch butterflies of Bt crops.
  30. 30. 3.5 U.6 Many plant species and some animal species have natural methods of cloning. • Plants use a variety of natural methods of cloning involving stems, roots, leaves or bulbs. • Garlic bulbs are modified plant leaves. All the bulbs in the group are genetically identical to each other. • Strawberry plants grow horizontal stems called runners that grow roots into the soil. These small plants develop into independent cloned strawberry plants http://www.caithness.org/photos/fpb/2009/february/aspen/aspen_5.jpg http://gardenpool.org/wpcontent/uploads/2010 /11/strawberry-plant.jpg
  31. 31. • At the very early embryo stage, cells are still pluripotent (meaning they can become any type of tissue) • These cells can be separated artificially in a laboratory in order to create more than one of the same organism • The separated pluripotent cells can then be inserted into the uterus of a surrogate mother or mothers in order to produce genetically identical offspring • The separation of cells has to happen early in development, preferably the 8 cell stage • This ability was first discovered by trying on Sea anemone 3.5 U.7 Animals can be cloned at the embryo stage by breaking up the embryo into more than one group of cells.
  32. 32. 3.5 U.8 Methods have been developed for cloning adult animals using differentiated cells. • Once cells start to differentiate and embryos develop into a fetus and eventually an adult cloning becomes much more difficult • Therapeutic cloning is an example of cloning using differentiated cells • This type of cloning can be used to create a specific tissue or organ • Cloning using differentiated cells can also be used to reproduce organisms like dolly the sheep. This is done through somatic-cell nuclear transfer.
  33. 33. • Organisms that reproduce asexually, produce genetically identical offspring • Identical twins in humans are also clones 3.5 A.4 Production of cloned embryos produced by somatic-cell nuclear transfer. [Dolly can be used as an example of somatic-cell transfer.]
  34. 34. 3.5 A.4 Production of cloned embryos produced by somatic-cell nuclear transfer. [Dolly can be used as an example of somatic-cell transfer.]
  35. 35. Step 1 A cell was taken from udder of adult sheep and grown in culture in a laboratory to create many daughter cells. 3.5 A.4 Production of cloned embryos produced by somatic-cell nuclear transfer. [Dolly can be used as an example of somatic-cell transfer.]
  36. 36. Step 2: An egg was taken from another sheep, and its nucleus was removed. Step 3: The udder cell and the de-nucleated egg were fused by electricity, stimulating the egg to develop as if it had been fertilized.
  37. 37. 3.5 A.4 Production of cloned embryos produced by somatic-cell nuclear transfer. [Dolly can be used as an example of somatic-cell transfer.]
  38. 38. Step 4: The embryo that developed was implanted into a surrogate mother sheep, and was born as Dolly, with the exact DNA from the original udder cell. 3.5 A.4 Production of cloned embryos produced by somatic-cell nuclear transfer. [Dolly can be used as an example of somatic-cell transfer.]
  39. 39. 3.5 A.4 Production of cloned embryos produced by somatic-cell nuclear transfer. [Dolly can be used as an example of somatic-cell transfer.]
  40. 40. 3.5 S.1 Design of an experiment to assess one factor affecting the rooting of stem-cuttings. [A plant species should be chosen for rooting experiments that forms roots readily in water or a solid medium.]

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