3 DNA technology has many useful applications The Human Genome ProjectThe production of vaccines, cancer drugs, and pesticidesEngineered bacteria that can clean up toxic wastes
4 Recombinant DNA Technology a set of techniques for combining genes from different sources into a single DNA molecule producing recombinant DNA.An organism that carries recombinant DNA is called a genetically modified (GM) organism.Recombinant DNA technology is applied in the field of biotechnology.Biotechnology uses various organisms to perform practical tasks.Plasmids are key tools for DNA technologyResearchers use plasmids to insert genes into bacteria
5 1 2 3 4 5 Cell containing gene of interest Bacterium Plasmid isolated DNAisolated3Gene inserted into plasmidBacterial chromosomePlasmidGene of interestRecombinant DNA (plasmid)DNA4Plasmid put into bacterial cellRecombinant bacterium5Cell multiplies with gene of interestCopies of geneCopies of proteinGene for pest resistance inserted into plantsClones of cellProtein used to make snow form at higher temperatureGene used to alter bacteria for cleaning up toxic wasteProtein used to dissolve blood clots in heart attack therapyFigure 12.3
6 From Humulin to Genetically Modified Foods By transferring the gene for a desired protein product into a bacterium, proteins can be produced in large quantities.
7 Making HumulinIn 1982, the world’s first genetically engineered pharmaceutical product was produced.Humulin, human insulin, was produced by genetically modified bacteria.Humulin was the first recombinant DNA drug approved by the FDA.DNA technology is also helping medical researchers develop vaccines.
8 12.16 Connection: Recombinant cells and organisms can mass-produce gene products Recombinant cells and organisms are used to manufacture useful proteinsTable 12.16
9 Human Gene TherapyHuman gene therapy is a recombinant DNA procedure that seeks to treat disease by altering the genes of the afflicted person.The mutant version of a gene is replaced or supplemented with a properly functioning one.
11 Treating Severe Combined Immunodeficiency SCID is a fatal inherited disease caused by a single defective gene.The gene prevents the development of the immune system.SCID patients quickly die unless treated with a bone marrow transplant.Since the year 2000,Gene therapy has successfully cured 22 children with inborn SCID.Unfortunately, three of the children developed leukemia and one of them died.
12 New genetic varieties of animals and plants are being produced Connection: Genetically modified organisms are transforming agricultureNew genetic varieties of animals and plants are being producedA plant with a new trait can be created using the Ti plasmid
13 Agrobacterium tumefaciens DNA containing gene for desired traitPlant cell123Ti plasmidRecombinant Ti plasmidInsertion of gene into plasmid using restriction enzyme and DNA ligaseIntroduction into plant cells in cultureRegeneration of plantT DNAT DNA carrying new gene within plant chromosomePlant with new traitRestriction siteFigure 12.18A
14 “Golden rice” has been genetically modified to contain beta-carotene This rice could help prevent vitamin A deficiencyFigure 12.18B
15 Recombinant DNA Techniques Recombinant DNA techniques can help biologists produce large quantities of a desired protein.Bacteria are the workhorses of modern biotechnology.To work with genes in the laboratory, biologists often use bacterial plasmids.Plasmids are small, circular DNA molecules that are separate from the much larger bacterial chromosome.
20 This splicing process can be accomplished using restriction enzymes. These enzymes cut DNA at specific nucleotide sequences.These cuts produce pieces of DNA called restriction fragmentsThat may have “sticky ends” that are important for joining DNA from different sources.DNA ligase pastes the DNA fragments togetherThe result is recombinant DNA
21 12.5 Genes can be cloned in recombinant plasmids: A closer look Bacteria take the recombinant plasmids and reproduceThis clones the plasmids and the genes they carryProducts of the gene can then be harvested
22 Bacterial clone carrying many copies of the human gene 1Isolate DNA from two sourcesHuman cellE. coli2Cut both DNAs with the same restrictionenzymePlasmidDNAGene VSticky ends3Mix the DNAs; they join by base-pairing4Add DNA ligase to bond the DNA covalentlyRecombinant DNA plasmidGene V5Put plasmid into bacterium by transformation6Clone the bacteriumBacterial clone carrying many copies of the human geneFigure 12.5
23 DNA Fingerprinting and Forensic Science DNA technology has rapidly revolutionized the field of forensics.Forensics is the scientific analysis of evidence from crime scenes.DNA fingerprinting can be used to determine whether or not two samples of genetic material are from a particular individual.
24 Murder, Paternity, and Ancient DNA DNA fingerprintingHas become a standard criminology tool.Has been used to identify victims of the September 11, 2001, World Trade Center attack.Can be used in paternity cases.DNA fingerprinting is also used in evolutionary researchTo study ancient pieces of DNA, such as that of Cheddar Man.
26 12.10 Gel electrophoresis sorts DNA molecules by size Restriction fragments of DNA can be sorted by sizeMixture of DNA molecules of different sizesLonger moleculesPower sourceGelShorter moleculesGlass platesCompleted gelFigure 12.10
27 The DNA fragments are visualized as “bands” on the gel. The bands of different DNA samples can then be compared.
29 One common application of gel electrophoresis is RFLP analysis Restriction fragment analysis is a powerful method that detects differences in DNA sequencesThe DNA molecules to be compared are exposed to a series of restriction enzymes.Scientists can compare DNA sequences of different individuals based on the size of the fragments
31 The Human Genome Project involves: Connection: The Human Genome Project is unlocking the secrets of our genesThe Human Genome Project involves:genetic and physical mapping of chromosomesDNA sequencingcomparison of human genes with those of other speciesFigure 12.14
32 RISKS AND ETHICAL QUESTIONS Connection: Could GM organisms harm human health or the environment?Genetic engineering involves some risksPossible ecological damage from pollen transfer between GM and wild cropsPollen from a transgenic variety of corn that contains a pesticide may stunt or kill monarch caterpillarsFigure 12.20A, B
33 12.21 Connection: DNA technology raises important ethical questions Our new genetic knowledge will affect our lives in many waysThe deciphering of the human genome, in particular, raises profound ethical issuesMany scientists have counseled that we must use the information wiselyFigure 12.21A-C