Biology_2007_Virtual_Lab_Answer_Key-1

3 what is a plasmid how is a plasmid used in gene

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3. What is a plasmid? How is a plasmid used in gene splicing? A plasmid is a small ring of DNA found in a bacterial cell. A plasmid is often used as a vehicle, or vector, to deliver DNA to a host organism. 4. What types of vectors are used to carry DNA from one species into the DNA of another species? Give examples. Biological and mechanical vectors are used in gene splicing. Examples of biological vectors include bacterial plasmids and viruses. Micropipettes and gene guns are
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examples of mechanical vectors. 5. What is a ‘transgenic organism’? Give examples. A transgenic organism is an organism that contains functional foreign DNA. Examples include a tobacco plant that glows in the dark (created by splicing the DNA that causes a firefly to glow into the DNA of a tobacco plant). Or a bacterium that produces human insulin (engineered by splicing the DNA that causes human insulin production into the DNA of an E. coli bacterium). 6. Why is it essential that the same restriction enzyme be used to cleave (cut) the DNA of both organisms used to create a transgenic organism? To be spliced together, both pieces of DNA must have matching sticky ends, so that the pieces will be capable of joining together at these ends. The only way to ensure that both pieces of DNA have matching ends, is to cut both of them with the same restriction enzyme. 7. Are there any factors other than technical ones that might slow ñ or even prevent ñ the use of bioengineering? Ethical questions, such as concerns regarding unintentional cruelty to transgenic animals, unanticipated health dangers that may be present in transgenic foods, and fears that gene-splicing will be used to create transgenic human beings are all factors that may slow or prevent the widespread use of bioengineering. Lab 16: Natural Selection Analysis The answers are intended only as samples. Answers also depend on how students completed the lab and on the random data generated by the computer. 1. Did either allele A or a disappear from the population you studied? Why or why not? Answers will vary. Both allele frequencies approached zero in the five generations of individuals observed in different environments (Allele A, Environment 1, 4; Allele a, Environment 2). This happens when natural selection favors one of the variations of the trait. The heterozygous individuals may display increased fitness over the homozygous individuals with the unfavorable trait. In this case, it will take longer for the frequency of the allele determining the unfavorable trait to disappear from the population. It may also take many more generations for such an allele to disappear if the initial frequency is high. 2. Did the effect of natural selection vary with different starting allele frequencies in identical environments? Why or why not?
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