Manipulation of DNA n Selective breeding has manipulated
Manipulation of DNA n Selective breeding has manipulated DNA f/ eons ¨ Domesticated ¨ Some n animals demonstrate the power of it dogs differ dramatically from their wolf ancestors Molecular approaches now possible ¨ Give ¨ We greater power, precision and speed can change one gene & transfer it ¨ Transfer between species © 2006 W. W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 1
Restriction Enzymes n Cut DNA at highly specific points ¨ Four to seven bases ¨ Each enzyme is unique n Consistent results © 2006 W. W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 2
Other Enzymes n Ligase ¨ Joins n DNA fragments together DNA Polymerase ¨ Makes copies of DNA of interest from a template © 2006 W. W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 3
Gel Electrophoresis n n Separation of DNA fragments Based on size © 2006 W. W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 4
Detection of Sickle-Cell © 2006 W. W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 5
DNA Hybridization n n Radioactive DNA probe Binds only to complimentary DNA template © 2006 W. W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 6
DNA Cloning n Makes many identical copies of a gene ¨ Necessary for certain operations: ¨ Sequencing, gene transfer, hybridization n DNA is obtained by screening a DNA library (a collection of different DNA pieces) © 2006 W. W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 7
Screening a DNA Library n n One DNA is isolated from the many The library is in bacteria which are plated on agar ¨ Form colonies ¨ Each colony has one gene n Screen by DNA hybridization ¨ DNA probe for gene of interest ¨ Isolate one colony and amplify it © 2006 W. W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 8
Polymerase Chain Reaction (PCR) Rapid cloning by polymerase amplification n Cycles through 3 temperatures n ¨ High – melting ¨ Low – annealing of primers ¨ Medium – polymerase extension © 2006 W. W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 9
PCR © 2006 W. W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 10
DNA Fingerprinting n Identifies individuals & is used in: ¨ Forensics cases ¨ Paternity cases RFLP analysis n PCR amplification n © 2006 W. W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 11
RFLP n n DNA cut with Restriction Enzyme Gel electrophoresis DNA hybridization Compare bands between suspects D V and see if match crime scene DNA © 2006 W. W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 12
Genetic Engineering n Transferring genes between organisms ¨ Genetically Modified Organism (GMO) Plasmids, viruses, or gene guns n Changes the phenotype n ¨ Faster growth ¨ Insect, herbicide, disease, or frost resistance ¨ Longer shelf-life © 2006 W. W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 13
GMO © 2006 W. W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 14
Human Cloning n Therapeutic Cloning ¨ Produces transplant tissues n Reproductive cloning ¨ Produces identical offspring (a clone) © 2006 W. W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 15
First Gene Therapy Patient Ashanthi De. Silva 1. Born w/o a properly functioning immune system 2. ADA (adenosine deaminase deficiency)
Gene Therapy © 2006 W. W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 17
Types of Gene therapy 1. Gene therapy currently only genetically engineers somatic cells The correction is not inherited & has to be performed every few months. ¨ Gene therapy that integrated into DNA did not have to be repeated, but caused cancer ¨ 2. Genetic engineering can also be done in germline, which will be inherited
Genetic engineering of germline n n Genetic engineering of people has begun! Parents will be able to make offspring at will!
Ethical Issues n Where should the limits be drawn? ¨ Bioengineering of bacteria, plants, dogs, humans? ¨ Pesticide resistance – more pesticide use? ¨ Bovine Growth Hormone – necessary? ¨ Human cloning – therapeutic, reproductive? ¨ Gene therapy – human bioengineering? © 2006 W. W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 20
Concept Quiz What is an advantage of restriction enzymes? A. B. C. D. They cut DNA into manageable-sized pieces. They cut at a specific sequence and, therefore, give consistent results. They leave sticky ends which can be used in cloning. All of the above © 2006 W. W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 21
Concept Quiz The purpose of a DNA library is to A. Store DNA B. Isolate specific genes C. Access DNA sequence information D. Genetically modify E. coli © 2006 W. W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 22
Concept Quiz RFLP analysis A. Is one method of DNA fingerprinting. B. Provides 100% accurate positive results. C. Is used in diagnosis of human diseases. D. All of the above. © 2006 W. W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 23
Process Animation 15. 1 Genetic Testing: Identifying the Sickle-Cell Allele Macintosh Windows © 2006 W. W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 24
Process Animation 15. 2 Constructing a DNA Library Macintosh Windows © 2006 W. W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 25
Process Animation 15. 3 a Human Cloning: Therapeutic Cloning Macintosh Windows © 2006 W. W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 26
Process Animation 15. 3 b Human Cloning: Reproductive Cloning Macintosh Windows © 2006 W. W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 27
Process Animation 15. 4 Genetic Engineering Macintosh Windows © 2006 W. W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 28
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