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

Other Enzymes n Ligase ¨ Joins n DNA fragments together DNA Polymerase ¨ Makes

Gel Electrophoresis n n Separation of DNA fragments Based on size © 2006 W.

Detection of Sickle-Cell © 2006 W. W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e

DNA Hybridization n n Radioactive DNA probe Binds only to complimentary DNA template ©

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

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

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