Essential idea: Biologists have developed techniques for artificial manipulation of DNA, cells and organisms.
There are a number of key techniques involved in the analysis of DNA and gene transfer. The image above shows nuclear transfer, the key step in cloning by somatic cell nuclear transfer. Dolly the sheep was the first success clone using this technique of direct cell manipulation. SCNT remains a key part of genetic engineering as it allows patient specific embryonic stem cells to be created, a key step in the application of gene therapies in a patient.
Understandings, applications and skills
| 3.5.U1 | Gel electrophoresis is used to separate proteins or fragments of DNA according to size. |
| 3.5.U2 | PCR can be used to amplify small amounts of DNA. |
| 3.5.U3 | DNA profiling involves comparison of DNA. |
| 3.5.U4 | Genetic modification is carried out by gene transfer between species. |
| 3.5.U5 | Clones are groups of genetically identical organisms, derived from a single original parent cell. |
| 3.5.U6 | Many plant species and some animal species have natural methods of cloning. |
| 3.5.U7 | Animals can be cloned at the embryo stage by breaking up the embryo into more than one group of cells. |
| 3.5.U8 | Methods have been developed for cloning adult animals using differentiated cells. |
| 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. |
[Text in square brackets indicates guidance notes]
Presentation and NotesThe presentation is designed to help your understanding. The notes outline is intended to be used as a framework for the development of student notes to aid revision.
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Weblinks
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PCR
PCR virtual lab by learn.genetics Manipulation techniques by DNAi Polymerase Chain Reaction by Sumanas Inc. Polymerase Chain Reaction by McGraw and Hill Gel Electrophoresis Paternity Testing by Sumanas Inc. |
DNA Profiling
DNA Fingerprinting by Bozeman Science Gene Transfer Genetic engineering to produce insulin by ABPI |
Nature of science
Assessing risks associated with scientific research—scientists attempt to assess the risks associated with genetically modified crops or livestock. (4.8)
Theory of knowledge
The use of DNA for securing convictions in legal cases is well established, yet even universally accepted theories are overturned in the light of new evidence in science. What criteria are necessary for assessing the reliability of evidence?
Read the Wasington Post article 'Convicted defendants left uninformed of forensic flaws found by Justice Dept.' to get an overview on forensic evidence as a whole.
Read the Wasington Post article 'Convicted defendants left uninformed of forensic flaws found by Justice Dept.' to get an overview on forensic evidence as a whole.
