Transcript
Page 1: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

www.cengage.com/biology/solomon

Albia Dugger • Miami Dade College

Eldra SolomonLinda BergDiana W. Martin

Chapter 15

DNA Technology and Genomics

Page 2: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Biotechnology

• Studies of DNA sequences reveal the organization of genes and the relationship between genes and their products

• Recombinant DNA technology allows researchers to splice together DNA from different organisms in the laboratory

• Molecular modification (genetic engineering) alters an organism’s DNA to produce new genes with new traits

• Biotechnology includes all commercial or industrial uses of cells or organisms

Page 3: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

15.1 DNA CLONING

LEARNING OBJECTIVES:

• Explain how a typical restriction enzyme cuts DNA molecules and give examples of the ways in which these enzymes are

used in recombinant DNA technology

• Distinguish among a genomic DNA library, a chromosome library, and a complementary DNA (cDNA) library; explain why

one would clone the same eukaryotic gene from both a genomic DNA library and a cDNA library

• Explain how researchers use a DNA probe

• Describe how PCR amplifies DNA in vitro

Page 4: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Recombinant DNA Technology

• Recombinant DNA technology began with genetic studies of viruses that infect bacteria (bacteriophages)

• Restriction enzymes from bacteria are used to cut DNA molecules in specific places – a vector molecule transports the DNA fragment into a cell

• Bacteriophages and plasmids are two examples of vectors

Page 5: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Recombinant DNA Technology (cont.)

• A plasmid with foreign DNA spliced into it (recombinant plasmid) is introduced into bacteria by transformation

• Once a plasmid enters a cell, it is replicated and distributed to daughter cells during cell division, producing many identical copies – the foreign DNA is cloned

Page 6: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Restriction Enzymes

• Restriction enzymes enable scientists to cut DNA from chromosomes into shorter fragments in a controlled way

• Each restriction enzyme cuts DNA at a specific DNA sequence (restriction site), such as 5′-AAGCTT-3′

• Many restriction enzymes used for recombinant DNA studies cut palindromic sequences – the base sequence reads the same as its complement, in the opposite direction – such as 3′-TTCGAA-5′

Page 7: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Sticky Ends

• Cutting both strands in a staggered fashion produces fragments with identical, complementary, single-stranded ends called sticky ends:

5′-A AGCTT -3′

3′-TTCGA A-5′

• Sticky ends pair by hydrogen bonding with the complementary, single-stranded ends of other DNA molecules that have been cut with the same enzyme

Page 8: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

DNA Ligase

• Once the sticky ends of two molecules have been joined, they are treated with DNA ligase, an enzyme that covalently links the two DNA fragments to form a stable recombinant DNA molecule

Page 9: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Cutting DNA with a Restriction Enzyme

Page 10: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Fig. 15-1, p. 325

Plus HindIII restriction enzyme

Sticky ends

Page 11: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Recombinant DNA

• The DNA to be cloned and plasmid (vector) DNA are cut with the same restriction enzyme

• The two DNA samples are mixed, and complementary bases of the sticky ends are bonded

• The result is recombinant DNA

Page 12: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Making Recombinant DNA

Page 13: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Fig. 15-2, p. 325

Plasmid from a bacterium

DNA of interest from another organism

Clonable DNA fragment

Recombinant DNA

1

2

3

Page 14: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Fig. 15-2, p. 325

Plasmid from a bacterium

DNA of interest from another organism

1

Recombinant DNA

Clonable DNA fragment

2

3 Stepped Art

Page 15: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Plasmids

• Plasmids used in recombinant DNA technology include features helpful in isolating and analyzing cloned DNA: • One or more restriction sites• Genes that let researchers select cells transformed by

recombinant plasmids

Page 16: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

A Plasmid Vector

Page 17: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Fig. 15-3a, p. 326

Aat I

Xba I

Hpa I

Pvu II

URA-3 Cla I

Sal I Bam HI Sma I

(a) This plasmid vector has many useful features. Researchers constructed it from DNA fragments they had isolated from plasmids, E. coli genes, and yeast genes. The two origins of replication, one for E. coli and one for yeast, Saccharomyces cerevisiae , let it replicate independently in either type of cell. Letters on the outer circle designate sites for restriction enzymes that cut the plasmid only at that position. Resistance genes for the antibiotics ampicillin and tetracycline and the yeast URA-3 gene are also shown. The URA-3 gene is useful when transforming yeast cells lacking an enzyme required for uracil synthesis. Cells that take up the plasmid grow on a uracil-deficient medium.

E. coli origin of replication

Page 18: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Plasmid in Bacterium

Page 19: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Fig. 15-3b, p. 326

Bacterial chromosome

Bacterium

Plasmid

(b) The relative sizes of a plasmid and the main DNA of a bacterium.

Page 20: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

DNA Libraries

• The total DNA in a cell is its genome

• A genomic DNA library is a collection of thousands of DNA fragments that represent all of the DNA in the genome

• A chromosome library contains all the DNA fragments in that specific chromosome

• A human genomic DNA library is stored in a collection of recombinant bacteria, each with a different fragment of DNA

Page 21: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Producing a Genomic DNA Library or Chromosome Library

Page 22: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Fig. 15-4, p. 327

Sites of cleavage

Fragment 1

Fragment 2

Fragment 3

Fragment 4

Human DNA

Produce recombinant DNA

Gene for resistance to antibiotic Transformation

R R R R

Bacterium without plasmid

Bacteria without plasmid fail to grow.

Bacteria with plasmid live and multiply to form a colony.

Plate with antibiotic-containing medium

1

2

3

4

Page 23: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Locating a Sequence of Interest

• To identify a plasmid containing a sequence of interest, each plasmid is cloned until there are millions of copies

• A sample of bacterial culture is spread on agar plates so cells are widely separated – each cell divides many times, forming a colony of genetically identical clones

• The next task is to determine which colony out of thousands contains the fragment of interest

Page 24: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

DNA Probes

• A segment of DNA that is homologous (identical) to part of the sequence of interest (DNA probe) can be used to detect the specific DNA sequence

• The DNA probe is a segment of single-stranded DNA that can hybridize (attach by base pairing) to complementary base sequences in target DNA

• DNA that is complementary to that particular probe is detected

Page 25: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

A cDNA Library

• It is possible to clone intact genes and avoid introns by using DNA copies of mature mRNA to construct complementary DNA (cDNA)

• Researchers use the enzyme reverse transcriptase to synthesize single-stranded cDNA, then DNA polymerase to make the cDNA double-stranded

• A cDNA library is formed using mRNA from a single cell type as the starting material

Page 26: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Formation of cDNA

Page 27: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Fig. 15-6, p. 329

Exon Intron Exon Intron Exon

DNA in a eukaryotic chromosome Transcription

Pre-mRNA RNA processing (remove introns)

Mature mRNA

Reverse transcriptase

mRNA Mature mRNAcDNA copy

of mRNA

Degraded RNA

cDNA

DNA polymerase

Double-stranded cDNA

1

2

3

4

5

Page 28: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

The Polymerase Chain Reaction

• The polymerase chain reaction (PCR) can be used to amplify a tiny sample of DNA without cloning in a cell

• PCR uses a heat-resistant DNA polymerase (Taq polymerase), nucleotides and primers to replicate a DNA sequence in vitro

• Cycles of denaturing (heating) and replication double the number of cloned molecules with each cycle

Page 29: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

The Polymerase Chain Reaction

Page 30: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Using PCR

• PCR enables researchers to amplify and analyze tiny DNA samples from a variety of sources, ranging from crime scenes to archaeological remains

• Example: Investigators have used PCR to analyze mitochondrial DNA obtained from the bones of Neandertals

Page 31: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

KEY CONCEPTS 15.1

• Scientists use DNA technology to produce many copies of specific genes (gene cloning)

Page 32: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

15.2 DNA ANALYSIS

LEARNING OBJECTIVES:

• Distinguish among DNA, RNA, and protein blotting

Page 33: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Gel Electrophoresis

• Gel electrophoresis is used to separate mixtures of certain macromolecules: proteins, polypeptides, or DNA fragments

• Nucleic acids migrate through the gel toward the positive pole of the electric field because they are negatively charged due to their phosphate groups

• DNA fragments are separated by size – small molecules move farther than large molecules

Page 34: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Gel Electrophoresis

Page 35: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Fig. 15-8a, p. 332

Standards of known sizes placed in well

Direction of movementMixtures

placed in well

Gel

Buffer solution +

1

Page 36: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Fig. 15-8b, p. 332

Anode

Longer molecules

Shorter molecules

Cathode

2

Page 37: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Fig. 15-8c, p. 332

3

Page 38: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Southern Blot

• DNA separated by gel electrophoresis is denatured and transferred to a membrane, which picks up DNA like a blotter picks up ink – this Southern blot is a replica of the gel

• The blot is incubated with a DNA probe, which hybridizes with any complementary DNA fragments – the probe is detected by autoradiography or chemical luminescence

Page 39: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Similar Blotting Techniques

• When RNA molecules separated by electrophoresis are transferred to a membrane and detected using a nucleic acid probe, the result is called a Northern blot

• When the blot consists of proteins or polypeptides separated by gel electrophoresis, it is called a Western blot

Page 40: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Southern Blotting Technique

Page 41: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Fig. 15-9, p. 333

DNA DNA fragments

Buffer solution

Agarose gel

WeightAbsorbent

paperLonger DNA fragments

Nitro-cellulose filter

Wick

BufferShorter DNA fragments

Radioactive probe solution

Gel

1 2

345

6 7

Page 42: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Restriction Fragment Length Polymorphisms (RFLPs)

• Random DNA mutations and recombination result in individuals with different lengths of fragments produced by a given restriction enzyme

• These restriction fragment length polymorphisms (RFLPs) can be used to determine how closely related different members of a population are

• A genetic polymorphism exists if individuals of two or more discrete types, or “morphs,” are found in a population

Page 43: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

RFLP Analysis

• RFLP analysis has been used for paternity testing and analyzing evidence found at crime scenes

• RFLP analysis helped map the exact location of gene mutations, such as the mutation that causes cystic fibrosis

• Today, RFLP analysis is rapidly being replaced by newer methods, such as automated DNA sequencing

Page 44: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Rapid DNA Sequencing

• Automated DNA-sequencing machines connected to powerful computers let scientists sequence huge amounts of DNA quickly and reliably

Page 45: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Automated DNA-Sequencing Results

Fig. 15-11, p. 335

Page 46: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Sequencing Entire Genomes

• Advances in sequencing technology have made it possible for researchers to study the nucleotide sequences of entire genomes in a wide variety of organisms

• The Human Genome Project, which sequenced the 3 billion base pairs of the human genome, was completed in 2001

• DNA sequence information is stored in large computer databases, many of which are accessed through the Internet

Page 47: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

KEY CONCEPTS 15.2

• Biologists study DNA using gel electrophoresis, DNA blotting, automated sequencing, and other methods

Page 48: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

15.3 GENOMICS

LEARNING OBJECTIVES:

• Describe three important areas of research in genomics

• Explain what a DNA microarray does

• Define pharmacogenetics and proteomics

Page 49: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Genomics

• Genomics is the study of the entire DNA sequence of an organism’s genome to identify all the genes, determine their RNA or protein products, and how the genes are regulated• Structural genomics: mapping and sequencing• Functional genomics: functions of genes and nongene

sequences • Comparative genomics: comparing genomes of different

species (evolution)• Metagenomics: analyzing communities of microorganisms

instead of individual organisms

Page 50: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

RNA Interference (RNAi)

• RNA interference (RNAi) can be used to quickly determine the function of a specific gene by inactivating the gene

• A short stretch of RNA complementary to part of the DNA sequence being examined is put into cells to silence the gene

• Biologists observe any changes in phenotype to help determine the function of the missing protein

Page 51: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Gene Targeting

• In gene targeting, the researcher chooses and “knocks out” (inactivates) a single gene in an organism

• Knockout mice are used to study the roles of proteins in numerous diseases

• A knockout gene is cloned and introduced into mouse embryonic stem cells (EScells), which are injected into early mouse embryos

Page 52: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

DNA Microarrays

• DNA microarrays provide a way to study patterns of gene expression in a variety of organisms

• Each spot in a DNA microarray contains copies of a single-stranded cDNA molecule, placed on a glass slide or chip

• cDNA molecules from two cell populations are tagged with different-colored fluorescent dyes and added to the array

• The array fluoresces at spots where hybridization occurs

Page 53: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

DNA Microarray Analysis

Page 54: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Fig. 15-12, p. 337

Treated cell

Untreated (control)

cell

Mature mRNAReverse transcriptase

Mature mRNAReverse transcriptase

cDNA copy of mRNA cDNA copy of mRNA

cDNA mRNA (discard)

cDNA mRNA (discard)

Laser 2

Emissions

Laser 1

1

2

3

4

5

6

Page 55: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Genome Sequencing for Other Species

• Comparison of the DNA sequences and chromosome organization of related genes from different species helps identify elements essential for their functions

• If a human gene has an unknown function• researchers can often deduce its role by studying the

equivalent gene in another species, such as a mouse or rat

Page 56: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

New Fields of Science

• bioinformatics (biological computing)• Storage, retrieval, and comparison of nucleotide or amino

acid sequences within and among species

• pharmacogenetics • Gene-based medicine; studies how genetic variation

among patients affects the action of drugs in individuals

• proteomics• Study of all proteins expressed by a cell at a given time

Page 57: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

KEY CONCEPTS 15.3

• Genomics is an emerging field that comprises the structure, function, and evolution of genomes

Page 58: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

15.4 APPLICATIONS OFDNA TECHNOLOGIES

LEARNING OBJECTIVE:

• Describe at least one important application of recombinant DNA technology in each of the following fields: medicine, DNA fingerprinting, and transgenic

organisms

Page 59: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

DNA Technology in Medicine

• Genetic tests determine whether an individual has a particular genetic mutation associated with disorders such as Huntington’s disease, hemophilia, cystic fibrosis, Tay-Sachs disease, breast cancer, and sickle cell anemia

• Gene therapy uses specific DNA to treat a genetic disease by correcting the genetic problem

Page 60: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Genetically Modified Proteins

• Recombinant DNA techniques are used to produce medical proteins in genetically altered bacteria or other organisms• Human insulin• Human growth hormone (GH)• Tissue-engineered skin grafts, cartilage, and other tissues• Human clotting factor VIII• Recombinant vaccines • influenza A, hepatitis B, polio, HPV

Page 61: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

DNA Fingerprinting

• The analysis of DNA fragments unique to an individual is known as DNA fingerprinting

• Today, DNA fingerprinting relies on PCR amplification, restriction enzyme digestion, and Southern blot hybridization to detect molecular markers

• The most useful markers are short tandem repeats (STRs) – short sequences of repetitive DNA, up to 200 nucleotide bases, with a simple pattern such as GTGTGTGTGT

Page 62: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

DNA Fingerprinting

• DNA fingerprints from a crime scene (middle), along with DNA profiles of seven suspects

• Which DNA profile matches blood from the crime scene?

Page 63: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Fig. 15-13, p. 340

1 2 3 From blood at crime scene

4 5 6 7

Page 64: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Applications of DNA Fingerprinting

1. Analyzing evidence found at crime scenes (forensic analysis)

2. Identifying mass disaster victims

3. Proving parentage in dogs for pedigree registration purposes

4. Identifying human cancer cell lines

5. Studying endangered species in conservation biology

6. Tracking tainted foods

7. Studying the genetic ancestry of human populations

8. Clarifying disputed parentage

9. Exonerating prisoners wrongfully convicted of a crime

Page 65: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Transgenic Organisms

• Plants and animals in which foreign genes have been incorporated are called transgenic organisms

• Transgenic animals are usually produced by injecting DNA of a particular gene into the nucleus of a fertilized egg or ES cell

Page 66: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Transgenic Organisms in Research

• Transgenic animals are used in research areas such as regulation of gene expression

• A mouse with two copies of the GH gene, grew to more than double normal size

Fig. 15-14, p. 341

Page 67: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Transgenic Animals and Genetically Modified Proteins

• “Pharming”

• Certain transgenic animals produce milk containing foreign proteins of therapeutic or commercial importance – such as human lactoferrin

Fig. 15-15, p. 341

Page 68: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Genetically Modified (GM) Crops

• The United States is the world’s top producer of transgenic or genetically modified (GM) crops

• Globally, 51% of the soybean crop, 31% of corn, 13% of cotton, and 5% of canola are GM crops

• GM plants are resistant to insect pests, viral and fungal diseases, heat, cold, herbicides, salty or acidic soil, or drought

• GM plants may also be engineered to increase nutrition, or to produce medically important proteins

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Transgenic Corn: Resistant to Drought

Page 70: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Fig. 15-16a, p. 342

(a) Note the poor yield in genetically unmodified corn plants used as a control.

Page 71: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Fig. 15-16b, p. 342

(b) Genetically modified corn plants withstood drought better than the unmodified corn.

Page 72: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Concerns About Health Effects

• Some people are concerned about the health effects of consuming foods derived from GM crops

• There is also ongoing controversy as to whether GM foods should be labeled

• In 1996, the U.S. Court of Appeals upheld the FDA position that labeling should not be required

Page 73: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

KEY CONCEPTS 15.4

• DNA technology and genomics have wide applications, from medical to forensic to agricultural

Page 74: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

15.5 DNA TECHNOLOGY HASRAISED SAFETY CONCERNS

LEARNING OBJECTIVE:

• Describe safety issues associated with recombinant DNA technology and explain how these issues are being

addressed

Page 75: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

SAFETY CONCERNS

• When recombinant DNA technology was introduced, scientists considered potential concerns:• An organism with undesirable environmental effects might

be accidentally produced• New strains of bacteria or other organisms might be

difficult to control

• So far, no evidence suggests that researchers have accidentally cloned hazardous genes

Page 76: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

Risk Assessment

• DNA technology in agriculture offers many potential benefits

• However, molecular modification poses some risks, such as the risk that genetically modified plants and animals could pass their foreign genes to wild relatives

Page 77: Www.cengage.com/biology/solomon Albia Dugger Miami Dade College Eldra Solomon Linda Berg Diana W. Martin Chapter 15 DNA Technology and Genomics

KEY CONCEPTS 15.5

• Scientists must assess the risks of each new recombinant organism


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