Biotechnology Chapter 20 Figure 20.1

Biotechnology Chapter 20 Figure 20.1
Figure 20.1 How can this array of spots be used to compare normal and cancerous tissues?

The DNA Toolbox Sequencing of the genomes of more than 7,000 species was under way in 2010 Recombinant DNA  nucleotide sequences from two different sources combined in vitro into the same DNA molecule © 2011 Pearson Education, Inc.

Genetic engineering  direct manipulation of genes for practical purposes
Biotechnology  manipulation of organisms or their genetic components to make useful products © 2011 Pearson Education, Inc.

DNA Cloning Foreign DNA inserted into plasmid*  plasmid inserted into bacterial cell Reproduction in bacterial cell  cloning of plasmid with foreign DNA  multiple copies of a single gene *Plasmids are small circular DNA molecules that replicate separately from the bacterial chromosome © 2011 Pearson Education, Inc.

Figure 20.2 Bacterium 1 Gene inserted into plasmid Cell containing gene of interest Bacterial chromosome Plasmid Gene of interest Recombinant DNA (plasmid) DNA of chromosome (“foreign” DNA) 2 Plasmid put into bacterial cell Recombinant bacterium 3 Host cell grown in culture to form a clone of cells containing the “cloned” gene of interest Protein expressed from gene of interest Gene of interest Copies of gene Protein harvested 4 Basic research and various applications Figure 20.2 A preview of gene cloning and some uses of cloned genes. Basic research on gene Basic research on protein Gene for pest resistance inserted into plants Gene used to alter bacteria for cleaning up toxic waste Protein dissolves blood clots in heart attack therapy Human growth hormone treats stunted growth

Using Restriction Enzymes to Make Recombinant DNA
Bacterial restriction enzymes cut DNA molecules at specific DNA sequences called restriction sites Yields restriction fragments Most useful restriction enzymes give staggered cut  “sticky ends.” Animation: Restriction Enzymes © 2011 Pearson Education, Inc.

Sticky ends bond with complementary sticky ends of other fragments
DNA ligase seals bonds between fragments © 2011 Pearson Education, Inc.

1 Restriction enzyme cuts sugar-phosphate backbones. Restriction site
Figure Restriction site 5 3 GAATTC DNA CTTAAG 3 5 1 Restriction enzyme cuts sugar-phosphate backbones. 3 5 5 3 G AATTC CTTAA G 5 Sticky end 3 3 5 Figure 20.3 Using a restriction enzyme and DNA ligase to make recombinant DNA.

1 2 Restriction enzyme cuts sugar-phosphate backbones.
Figure Restriction site 5 3 GAATTC DNA CTTAAG 3 5 1 Restriction enzyme cuts sugar-phosphate backbones. 3 5 5 3 G AATTC CTTAA G 5 Sticky end 3 3 5 5 3 AATTC G G 2 DNA fragment added from another molecule cut by same enzyme. Base pairing occurs. 3 CTTAA 5 Figure 20.3 Using a restriction enzyme and DNA ligase to make recombinant DNA. 5 3 5 3 5 3 G AATT C G AATT C C TTAA G C TTAA G 3 5 3 5 3 5 One possible combination

1 2 3 Restriction enzyme cuts sugar-phosphate backbones.
Figure Restriction site 5 3 GAATTC DNA CTTAAG 3 5 1 Restriction enzyme cuts sugar-phosphate backbones. 3 5 5 3 G AATTC CTTAA G 5 Sticky end 3 3 5 5 3 AATTC G G 2 DNA fragment added from another molecule cut by same enzyme. Base pairing occurs. 3 CTTAA 5 Figure 20.3 Using a restriction enzyme and DNA ligase to make recombinant DNA. 5 3 5 3 5 3 G AATT C G AATT C C TTAA G C TTAA G 3 5 3 5 3 5 One possible combination 3 DNA ligase seals strands 5 3 3 Recombinant DNA molecule 5

Cloning a Eukaryotic Gene in a Bacterial Plasmid
A cloning vector (original plasmid)  DNA molecule that carries foreign DNA into a host cell © 2011 Pearson Education, Inc.

Figure 20.4 TECHNIQUE Hummingbird cell Bacterial plasmid ampR gene lacZ gene Restriction site Sticky ends Gene of interest Humming- bird DNA fragments Recombinant plasmids Nonrecombinant plasmid Bacteria carrying plasmids Figure 20.4 Research Method: Cloning Genes in Bacterial Plasmids RESULTS Colony carrying recombinant plasmid with disrupted lacZ gene Colony carrying nonrecombinant plasmid with intact lacZ gene One of many bacterial clones

Humming- bird DNA fragments
Figure 20.4a-1 TECHNIQUE Hummingbird cell Bacterial plasmid ampR gene lacZ gene Restriction site Sticky ends Gene of interest Humming- bird DNA fragments Figure 20.4 Research Method: Cloning Genes in Bacterial Plasmids

Figure 20.4a-2 TECHNIQUE Hummingbird cell Bacterial plasmid ampR gene lacZ gene Restriction site Sticky ends Gene of interest Humming- bird DNA fragments Recombinant plasmids Nonrecombinant plasmid Figure 20.4 Research Method: Cloning Genes in Bacterial Plasmids

Figure 20.4a-3 TECHNIQUE Hummingbird cell Bacterial plasmid ampR gene lacZ gene Restriction site Sticky ends Gene of interest Humming- bird DNA fragments Recombinant plasmids Nonrecombinant plasmid Figure 20.4 Research Method: Cloning Genes in Bacterial Plasmids Bacteria carrying plasmids

Bacteria carrying plasmids
Figure 20.4b Bacteria carrying plasmids RESULTS Colony carrying recombinant plasmid with disrupted lacZ gene Colony carrying nonrecombinant plasmid with intact lacZ gene Figure 20.4 Research Method: Cloning Genes in Bacterial Plasmids One of many bacterial clones

Storing Cloned Genes in DNA Libraries
A genomic library is made using plasmids or bacteriophages © 2011 Pearson Education, Inc.

Cut with restriction enzymes into either small fragments or
Figure 20.5 Foreign genome Cut with restriction enzymes into either small fragments or large fragments Bacterial artificial chromosome (BAC) Large insert with many genes (b) BAC clone Recombinant plasmids Figure 20.5 Genomic libraries. Plasmid clone (a) Plasmid library (c) Storing genome libraries

Complementary DNA (cDNA) library
Made by cloning DNA made in vitro by reverse transcription of all the mRNA produced by a particular cell A cDNA library represents only the subset of genes transcribed into mRNA in the original cells © 2011 Pearson Education, Inc.

DNA in nucleus mRNAs in cytoplasm Figure 20.6-1
Figure 20.6 Making complementary DNA (cDNA) from eukaryotic genes.

Reverse transcriptase Poly-A tail mRNA 5 3 3 5 DNA strand Primer
Figure DNA in nucleus mRNAs in cytoplasm Reverse transcriptase Poly-A tail mRNA 5 A A A A A A 3 3 T T T T T 5 DNA strand Primer Figure 20.6 Making complementary DNA (cDNA) from eukaryotic genes.

Figure DNA in nucleus mRNAs in cytoplasm Reverse transcriptase Poly-A tail mRNA 5 A A A A A A 3 3 T T T T T 5 DNA strand Primer 5 A A A 3 A A A 3 T T T T T 5 Figure 20.6 Making complementary DNA (cDNA) from eukaryotic genes.

Figure DNA in nucleus mRNAs in cytoplasm Reverse transcriptase Poly-A tail mRNA 5 A A A A A A 3 3 T T T T T 5 DNA strand Primer 5 A A A 3 A A A 3 T T T T T 5 Figure 20.6 Making complementary DNA (cDNA) from eukaryotic genes. 5 3 3 5 DNA polymerase

Figure DNA in nucleus mRNAs in cytoplasm Reverse transcriptase Poly-A tail mRNA 5 A A A A A A 3 3 T T T T T 5 DNA strand Primer 5 A A A 3 A A A 3 T T T T T 5 Figure 20.6 Making complementary DNA (cDNA) from eukaryotic genes. 5 3 3 5 DNA polymerase 5 3 3 5 cDNA

Screening a Library for Clones Carrying a Gene of Interest
Identified with a nucleic acid probe having a sequence complementary to the gene Process is called nucleic acid hybridization © 2011 Pearson Education, Inc.

For example, if the desired gene is
A probe can be synthesized that is complementary to the gene of interest For example, if the desired gene is – Then we would synthesize this probe 5  CTCAT CACCGGC 3 Figure 20.UN01 In-text figure, p. 401, Figure 20.UN02 In-text figure, p. 401 3 G A G T A G T G G C C G 5 © 2011 Pearson Education, Inc.

Radioactively labeled probe molecules 5 3  CTCATCACCGGC
Figure 20.7 TECHNIQUE Radioactively labeled probe molecules 5 3  CTCATCACCGGC Gene of interest GAGTAGTGGCCG 3 5 Probe DNA Film Single- stranded DNA from cell Multiwell plates holding library clones Figure 20.7 Research Method: Detecting a Specific DNA Sequence by Hybridization with a Nucleic Acid Probe Nylon membrane Location of DNA with the complementary sequence Nylon membrane

Eukaryotic Cloning and Expression Systems
Avoid eukaryote-bacterial incompatibility issues by using eukaryotic cells, such as yeasts or cultured mammal cells, as hosts for cloning and expressing genes © 2011 Pearson Education, Inc.

Electroporation: applying a brief electrical pulse to create temporary holes in plasma membranes  introduces recombinant DNA into eukaryotic cells Alternatively, scientists can inject DNA into cells using microscopically thin needles © 2011 Pearson Education, Inc.

Cross-Species Gene Expression and Evolutionary Ancestry
The remarkable ability of bacteria to express some eukaryotic proteins underscores the shared evolutionary ancestry of living species e.g., Pax-6 (gene that directs formation of vertebrate eye); also directs the formation of insect eye © 2011 Pearson Education, Inc.

Amplifying DNA in Vitro: The Polymerase Chain Reaction (PCR)
Polymerase chain reaction, PCR produce many copies of a specific target segment of DNA Key to PCR is an unusual, heat-stable DNA polymerase called Taq polymerase. © 2011 Pearson Education, Inc.

Cycle 1 yields 2 molecules Cycle 2 yields 4 molecules
Figure 20.8 TECHNIQUE 5 3 Target sequence Genomic DNA 3 5 1 Denaturation 5 3 3 5 2 Annealing Cycle 1 yields 2 molecules Primers 3 Extension New nucleotides Figure 20.8 Research Method: The Polymerase Chain Reaction (PCR) Cycle 2 yields 4 molecules Cycle 3 yields 8 molecules; 2 molecules (in white boxes) match target sequence

TECHNIQUE 5 3 Target sequence Genomic DNA 3 5 Figure 20.8a
Figure 20.8 Research Method: The Polymerase Chain Reaction (PCR)

Cycle 1 yields 2 molecules
Figure 20.8b 1 Denaturation 5 3 3 5 2 Annealing Cycle 1 yields 2 molecules Primers 3 Extension Figure 20.8 Research Method: The Polymerase Chain Reaction (PCR) New nucleotides

Cycle 2 yields 4 molecules
Figure 20.8c Cycle 2 yields 4 molecules Figure 20.8 Research Method: The Polymerase Chain Reaction (PCR)

Figure 20.8d Cycle 3 yields 8 molecules; 2 molecules (in white boxes) match target sequence Figure 20.8 Research Method: The Polymerase Chain Reaction (PCR)

Gel Electrophoresis and Southern Blotting
Gel electrophoresis  method of rapidly analyzing and comparing genomes Uses a gel as a molecular sieve to separate nucleic acids or proteins by size, electrical charge, and other properties Animation: Biotechnology Lab © 2011 Pearson Education, Inc.

Mixture of DNA molecules of different sizes  Cathode Anode 
Figure 20.9 TECHNIQUE 1 Power source Mixture of DNA molecules of different sizes  Cathode Anode  Wells Gel 2 Power source   Longer molecules Shorter molecules RESULTS Figure 20.9 Research Method: Gel Electrophoresis

Mixture of DNA molecules of different sizes  Cathode Anode 
Figure 20.9a TECHNIQUE 1 Power source Mixture of DNA molecules of different sizes  Cathode Anode  Wells Gel 2 Power source Figure 20.9 Research Method: Gel Electrophoresis   Longer molecules Shorter molecules

Figure 20.9b RESULTS Figure 20.9 Research Method: Gel Electrophoresis

Variations in DNA sequence are called polymorphisms
Sequence changes that alter restriction sites are called RFLPs (restriction fragment length polymorphisms) © 2011 Pearson Education, Inc.

Normal -globin allele Normal allele Sickle-cell allele
Figure 20.10 Normal -globin allele Normal allele Sickle-cell allele 175 bp 201 bp Large fragment DdeI DdeI DdeI DdeI Large fragment Sickle-cell mutant -globin allele 376 bp 201 bp 376 bp Large fragment 175 bp DdeI DdeI DdeI Figure Using restriction fragment analysis to distinguish the normal and sickle-cell alleles of the human -globin gene. (a) DdeI restriction sites in normal and sickle-cell alleles of the -globin gene (b) Electrophoresis of restriction fragments from normal and sickle-cell alleles

Normal -globin allele
Figure 20.10a Normal -globin allele 175 bp 201 bp Large fragment DdeI DdeI DdeI DdeI Sickle-cell mutant -globin allele 376 bp Large fragment Figure Using restriction fragment analysis to distinguish the normal and sickle-cell alleles of the human -globin gene. DdeI DdeI DdeI (a) DdeI restriction sites in normal and sickle-cell alleles of the -globin gene

Normal allele Sickle-cell allele Large fragment 376 bp 201 bp 175 bp
Figure 20.10b Normal allele Sickle-cell allele Large fragment 376 bp 201 bp 175 bp Figure Using restriction fragment analysis to distinguish the normal and sickle-cell alleles of the human -globin gene. (b) Electrophoresis of restriction fragments from normal and sickle-cell alleles

Southern blotting combines gel electrophoresis of DNA fragments with nucleic acid hybridization
© 2011 Pearson Education, Inc.

Restriction fragments DNA  restriction enzyme I II III
Figure 20.11 TECHNIQUE Heavy weight Restriction fragments DNA  restriction enzyme I II III Nitrocellulose membrane (blot) Gel Sponge I Normal -globin allele II Sickle-cell allele III Heterozygote Alkaline solution Paper towels 1 Preparation of restriction fragments 2 Gel electrophoresis 3 DNA transfer (blotting) Probe base-pairs with fragments I II III I II III Figure Research Method: Southern Blotting of DNA Fragments Radioactively labeled probe for -globin gene Fragment from sickle-cell -globin allele Film over blot Fragment from normal - globin allele Nitrocellulose blot 4 Hybridization with labeled probe 5 Probe detection

DNA Sequencing Relatively short DNA fragments can be sequenced by the dideoxy chain termination method, the first automated method to be employed Modified nucleotides called dideoxyribonucleotides (ddNTP) attach to synthesized DNA strands of different lengths Each type of ddNTP is tagged with a distinct fluorescent label that identifies the nucleotide at the end of each DNA fragment The DNA sequence can be read from the resulting spectrogram © 2011 Pearson Education, Inc.

Figure 20.12 TECHNIQUE DNA (template strand) Primer Deoxyribonucleotides Dideoxyribonucleotides (fluorescently tagged) T 3 5 G C T dATP ddATP T T 5 G dCTP ddCTP A C DNA polymerase dTTP ddTTP T T dGTP ddGTP C G A P P P P P P C G G A 3 A OH H DNA (template strand) Labeled strands 5 3 C ddG T ddA A G ddC C C A ddT T T T C ddG G G G G T ddA A A A A A T ddA A A A A A A C ddG G G G G G G G G ddC C C C C C C C C A T T T T T T T T T T T T T T T T T C G G G G G G G G G A T T T T T T T T T 3 A T T T T T T T T T 5 Shortest Longest Direction of movement of strands Longest labeled strand Figure Research Method: Dideoxy Chain Termination Method for Sequencing DNA Detector Laser Shortest labeled strand RESULTS Last nucleotide of longest labeled strand G A C T G Last nucleotide of shortest labeled strand A A G C

Deoxyribonucleotides Dideoxyribonucleotides (fluorescently tagged)
Figure 20.12a TECHNIQUE DNA (template strand) Primer Deoxyribonucleotides Dideoxyribonucleotides (fluorescently tagged) T 3 G 5 C T dATP ddATP T T 5 G dCTP ddCTP A C DNA polymerase dTTP ddTTP T T dGTP ddGTP C G A P P P P P P G C G Figure Research Method: Dideoxy Chain Termination Method for Sequencing DNA A A OH H 3

Direction of movement of strands Longest labeled strand
Figure 20.12b TECHNIQUE (continued) DNA (template strand) Labeled strands 3 5 C ddG T ddA A G ddC C C A ddT T T T C ddG G G G G T A A A A A ddA T ddA A A A A A A C ddG G G G G G G G G ddC C C C C C C C C A T T T T T T T T T C G G G G G G G G G A T T T T T T T T T 3 A T T T T T T T T T 5 Shortest Longest Direction of movement of strands Longest labeled strand Figure Research Method: Dideoxy Chain Termination Method for Sequencing DNA Detector Laser Shortest labeled strand

Direction of movement of strands Longest labeled strand
Figure 20.12c Direction of movement of strands Longest labeled strand Detector Laser Shortest labeled strand RESULTS Last nucleotide of longest labeled strand G A C Figure Research Method: Dideoxy Chain Termination Method for Sequencing DNA T G A Last nucleotide of shortest labeled strand A G C

Reverse transcriptase-polymerase chain reaction (RT-PCR)
Reverse transcriptase + mRNA  cDNA, which serves as a template for PCR amplification of the gene of interest © 2011 Pearson Education, Inc.

TECHNIQUE 1 cDNA synthesis mRNAs cDNAs Primers 2 PCR amplification
Figure 20.13 TECHNIQUE 1 cDNA synthesis mRNAs cDNAs Primers 2 PCR amplification -globin gene 3 Gel electrophoresis Figure Research Method: RT-PCR Analysis of the Expression of Single Genes RESULTS Embryonic stages 1 2 3 4 5 6

Expression of Interacting Groups of Genes
DNA microarray assays  compare patterns of gene expression in different tissues, at different times, or under different conditions © 2011 Pearson Education, Inc.

Labeled cDNA molecules (single strands)
Figure 20.15 TECHNIQUE 1 Isolate mRNA. Tissue sample 2 Make cDNA by reverse transcription, using fluorescently labeled nucleotides. mRNA molecules Labeled cDNA molecules (single strands) 3 Apply the cDNA mixture to a microarray, a different gene in each spot. The cDNA hybridizes with any complementary DNA on the microarray. DNA fragments representing a specific gene Figure Research Method: DNA Microarray Assay of Gene Expression Levels DNA microarray 4 Rinse off excess cDNA; scan microarray for fluorescence. Each fluorescent spot (yellow) represents a gene expressed in the tissue sample. DNA microarray with 2,400 human genes

DNA microarray with 2,400 human genes
Figure 20.15a DNA microarray with 2,400 human genes Figure Research Method: DNA Microarray Assay of Gene Expression Levels

Determining Gene Function
in vitro mutagenesis  mutations are introduced into a cloned gene, altering or destroying its function Mutated gene returned to the cell normal gene function determined by examining the mutant’s phenotype Gene expression can also be silenced using RNA interference (RNAi) © 2011 Pearson Education, Inc.

Genetic markers called SNPs (single nucleotide polymorphisms) occur on average every 100–300 base pairs SNPs can be detected by PCR, and any SNP shared by people affected with a disorder but not among unaffected people may pinpoint the location of the disease-causing gene © 2011 Pearson Education, Inc.

Disease-causing allele
Figure 20.16 DNA T Normal allele SNP C Figure Single nucleotide polymorphisms (SNPs) as genetic markers for disease-causing alleles. Disease-causing allele

Cloning Plants: Single-Cell Cultures
Totipotent cell can generate a complete new organism Plant cloning is used extensively in agriculture © 2011 Pearson Education, Inc.

Cross section of carrot root
Figure 20.17 Cross section of carrot root 2-mg fragments Fragments were cultured in nu- trient medium; stirring caused single cells to shear off into the liquid. Figure The cloning of a whole carrot plant from a single carrot cell. Single cells free in suspension began to divide. Embryonic plant developed from a cultured single cell. Plantlet was cultured on agar medium. Later it was planted in soil. Adult plant

Cloning Animals: Nuclear Transplantation
Nucleus of an unfertilized egg cell is replaced with the nucleus of a differentiated cell © 2011 Pearson Education, Inc.

Egg with donor nucleus activated to begin development
Figure 20.18 EXPERIMENT Frog embryo Frog egg cell Frog tadpole UV Fully differentiated (intestinal) cell Less differentiated cell Donor nucleus trans- planted Donor nucleus trans- planted Enucleated egg cell Egg with donor nucleus activated to begin development RESULTS Figure Inquiry: Can the nucleus from a differentiated animal cell direct development of an organism? Most develop into tadpoles. Most stop developing before tadpole stage.

Reproductive Cloning of Mammals
1997, Scottish researchers announced the birth of Dolly, a lamb cloned from an adult sheep by nuclear transplantation from a differentiated mammary cell © 2011 Pearson Education, Inc.

Cultured mammary cells
Figure 20.19 TECHNIQUE Mammary cell donor Egg cell donor 1 2 Egg cell from ovary Nucleus removed 3 Cells fused Cultured mammary cells Nucleus from mammary cell 4 Grown in culture Early embryo 5 Implanted in uterus of a third sheep Figure Research Method: Reproductive Cloning of a Mammal by Nuclear Transplantation Surrogate mother 6 Embryonic development RESULTS Lamb (“Dolly”) genetically identical to mammary cell donor

Cultured mammary cells
Figure 20.19a TECHNIQUE Mammary cell donor Egg cell donor 1 2 Egg cell from ovary Nucleus removed 3 Cells fused Cultured mammary cells Figure Research Method: Reproductive Cloning of a Mammal by Nuclear Transplantation Nucleus from mammary cell

Nucleus from mammary cell
Figure 20.19b Nucleus from mammary cell 4 Grown in culture Early embryo 5 Implanted in uterus of a third sheep Surrogate mother Figure Research Method: Reproductive Cloning of a Mammal by Nuclear Transplantation 6 Embryonic development RESULTS Lamb (“Dolly”) genetically identical to mammary cell donor

Cloned animals do not always look or behave exactly the same
Since 1997, cloning has been demonstrated in many mammals, including mice, cats, cows, horses, mules, pigs, and dogs CC (for Carbon Copy) was the first cat cloned; however, CC differed somewhat from her female “parent” Cloned animals do not always look or behave exactly the same © 2011 Pearson Education, Inc.

Figure 20.20 Figure CC, the first cloned cat, and her single parent.

Stem Cells of Animals Relatively unspecialized cell that can reproduce itself indefinitely and differentiate into specialized cells of one or more types Stem cells isolated from early embryos at the blastocyst stage are called embryonic stem (ES) cells; these are able to differentiate into all cell types The adult body also has stem cells, which replace nonreproducing specialized cells © 2011 Pearson Education, Inc.

Cells generating all embryonic cell types
Figure 20.21 Embryonic stem cells Adult stem cells Cells generating all embryonic cell types Cells generating some cell types Cultured stem cells Different culture conditions Figure Working with stem cells. Liver cells Nerve cells Blood cells Different types of differentiated cells

Practical applications of DNA technology

Diagnosis and Treatment of Diseases
Can diagnose PCR and sequence-specific primers, then sequencing the amplified product to look for the disease-causing mutation SNPs may be associated with a disease-causing mutation © 2011 Pearson Education, Inc.

Human Gene Therapy The alteration of an afflicted individual’s genes

Insert RNA version of normal allele into retrovirus.
Figure 20.23 Cloned gene 1 Insert RNA version of normal allele into retrovirus. Viral RNA 2 Let retrovirus infect bone marrow cells that have been removed from the patient and cultured. Retrovirus capsid 3 Viral DNA carrying the normal allele inserts into chromosome. Bone marrow cell from patient Figure Gene therapy using a retroviral vector. Bone marrow 4 Inject engineered cells into patient.

Pharmaceutical Products
Advances in DNA technology and genetic research are important to the development of new drugs to treat diseases © 2011 Pearson Education, Inc.

Protein Production by “Pharm” Animals
Transgenic animals are made by introducing genes from one species into the genome of another animal  pharmaceutical “factories” © 2011 Pearson Education, Inc.

Figure 20.24 Figure Goats as “pharm” animals.

Forensic Evidence and Genetic Profiles
An individual’s unique DNA sequence, or genetic profile, can be obtained by analysis of tissue or body fluids Can use PCR and/ or Southern Blotting/ RFLP © 2011 Pearson Education, Inc.

Figure 20.25 This photo shows Washington just before his release in 2001, after 17 years in prison. (a) Source of sample STR marker 1 STR marker 2 STR marker 3 Figure STR analysis used to release an innocent man from prison. Semen on victim 17,19 13,16 12,12 Earl Washington 16,18 14,15 11,12 Kenneth Tinsley 17,19 13,16 12,12 (b) These and other STR data exonerated Washington and led Tinsley to plead guilty to the murder.

Environmental Cleanup
Modified microorganisms can be used to extract minerals from the environment or degrade potentially toxic waste materials © 2011 Pearson Education, Inc.

Agricultural Applications
DNA technology is being used to improve agricultural productivity and food quality Genetic engineering of transgenic animals speeds up the selective breeding process Beneficial genes can be transferred between varieties of species © 2011 Pearson Education, Inc.

The Ti plasmid is the most commonly used vector for introducing new genes into plant cells
Genetic engineering in plants has been used to transfer many useful genes including those for herbicide resistance, increased resistance to pests, increased resistance to salinity, and improved nutritional value of crops © 2011 Pearson Education, Inc.

Agrobacterium tumefaciens
Figure 20.26 TECHNIQUE Agrobacterium tumefaciens Ti plasmid Site where restriction enzyme cuts T DNA DNA with the gene of interest RESULTS Figure Research Method: Using the Ti Plasmid to Produce Transgenic Plants Recombinant Ti plasmid Plant with new trait

Safety and Ethical Questions Raised by DNA Technology
Potential benefits of genetic engineering must be weighed against potential hazards of creating harmful products or procedures Guidelines are in place in the United States and other countries to ensure safe practices for recombinant DNA technology © 2011 Pearson Education, Inc.

Genetically modified (GM) organisms

Biotechnology Chapter 20 Figure 20.1

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