20 lectures ppt
TRANSCRIPT
-
8/7/2019 20 Lectures PPT
1/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
PowerPoint Lectures for
Biology, Seventh Edition
Neil Campbell and Jane Reece
Lectures by Chris Romero
Chapter 20Chapter 20
DNA Technology
and Genomics
-
8/7/2019 20 Lectures PPT
2/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Overview: Understanding and ManipulatingGenomes
Sequencing of the human genome was largelycompleted by 2003
DNA sequencing has depended on advances in
technology, starting with making recombinant DNA
In recombinant DNA, nucleotide sequences from
two different sources, often two species, are
combined in vitro into the same DNA molecule
Methods for making recombinant DNA are central
to genetic engineering, the direct manipulation of
genes for practical purposes
-
8/7/2019 20 Lectures PPT
3/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
DNA technology has revolutionized biotechnology,the manipulation of organisms or their genetic
components to make useful products
An example ofDNA technology is the microarray,
a measurement of gene expression of thousands
of different genes
-
8/7/2019 20 Lectures PPT
4/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
-
8/7/2019 20 Lectures PPT
5/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Concept 20.1: DNA cloning permits production ofmultiple copies of a specific gene or other DNA segment
To work directly with specific genes, scientists
prepare gene-sized pieces ofDNA in identical
copies, a process called gene cloning
-
8/7/2019 20 Lectures PPT
6/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
DNA Cloning and Its Applications: A Preview
Most methods for cloning pieces ofDNA in thelaboratory share general features, such as the use
of bacteria and their plasmids
Cloned genes are useful for making copies of a
particular gene and producing a gene product
-
8/7/2019 20 Lectures PPT
7/66
LE 20-2Bacterium
Bacterial
chromosome
Plasmid
Gene inserted intoplasmid
Cell containing geneof interest
Gene ofinterest DNA of
chromosome
RecombinantDNA (plasmid)
Plasmid put intobacterial cell
Recombinantbacterium
Host cell grown in cultureto form a clone of cellscontaining the cloned
gene of interest
Protein expressedby gene of interest
Protein harvested
Gene ofinterest
Copies of gene
Basicresearchon gene
Basicresearchon protein
Basic research andvarious applications
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 hor-
mone treats stunted
growth
-
8/7/2019 20 Lectures PPT
8/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Using Restriction Enzymes to Make RecombinantDNA
Bacterial restriction enzymes cut DNA moleculesat DNA sequences called restriction sites
A restriction enzyme usually makes many cuts,
yielding restriction fragments
The most useful restriction enzymes cut DNA in a
staggered way, producing fragments with sticky
ends that bond with complementary sticky ends
of other fragments
DNA ligase is an enzyme that seals the bonds
between restriction fragments
-
8/7/2019 20 Lectures PPT
9/66
LE 20-3Restriction site
DNA5d3d
3d5d
Restriction enzyme cutsthe sugar-phosphatebackbones at each arrow.
One possible combination
DNA fragment from anothersource is added. Base pairingof sticky ends producesvarious combinations.
Fragment from differentDNA molecule cut by thesame restriction enzyme
DNA ligaseseals the strands.
Recombinant DNA molecule
Sticky end
-
8/7/2019 20 Lectures PPT
10/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Animation: Restriction EnzymesAnimation: Restriction Enzymes
-
8/7/2019 20 Lectures PPT
11/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Cloning a Eukaryotic Gene in a Bacterial Plasmid
In gene cloning, the original plasmid is called acloning vector
A cloning vector is a DNA molecule that can carry
foreign DNA into a cell and replicate there
-
8/7/2019 20 Lectures PPT
12/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Producing Clones of Cells
Cloning a human gene in a bacterial plasmid canbe divided into six steps:
1. Vector and gene-source DNA are isolated
2. DNA is inserted into the vector
3. Human DNA fragments are mixed with cutplasmids, and base-pairing takes place
4. Recombinant plasmids are mixed with bacteria
5. The bacteria are plated and incubated
6. Cell clones with the right gene are identified
Animation: Cloning a GeneAnimation: Cloning a Gene
-
8/7/2019 20 Lectures PPT
13/66
LE 20-4_1
Isolate plasmid DNA
and human DNA.
Cut both DNA samples with
the same restriction enzyme.
Mix the DNAs; they join by base pairing.
The products are recombinant plasmidsand many nonrecombinant plasmids.
Bacterial cell lacZ gene
(lactose
breakdown)
Human
cell
Restriction
site
ampRgene
(ampicillinresistance)
Bacterial
plasmid Gene of
interest
Sticky
endsHuman DNA
fragments
Recombinant DNA plasmids
-
8/7/2019 20 Lectures PPT
14/66
LE 20-4_2
Isolate plasmid DNA
and human DNA.
Cut both DNA samples with
the same restriction enzyme.
Mix the DNAs; they join by base pairing.
The products are recombinant plasmids
and many nonrecombinant plasmids.
Bacterial cell lacZ gene
(lactose
breakdown)
Human
cell
Restriction
site
ampRgene
(ampicillin
resistance)
Bacterial
plasmid Gene of
interest
Sticky
endsHuman DNA
fragments
Recombinant DNA plasmids
Introduce the DNA into bacterial cells
that have a mutation in their own lacZ
gene.
Recombinant
bacteria
-
8/7/2019 20 Lectures PPT
15/66
LE 20-4_3
Isolate plasmid DNA
and human DNA.
Cut both DNA samples with
the same restriction enzyme.
Mix the DNAs; they join by base pairing.
The products are recombinant plasmids
and many nonrecombinant plasmids.
Bacterial cell lacZ gene
(lactose
breakdown)
Human
cell
Restriction
site
ampRgene
(ampicillinresistance)
Bacterial
plasmid Gene ofinterest
Sticky
endsHuman DNAfragments
Recombinant DNA plasmids
Introduce the DNA into bacterial cells
that have a mutation in their own lacZ
gene.
Recombinant
bacteria
Plate the bacteria on agar
containing ampicillin and X-gal.
Incubate until colonies grow.
Colony carrying non-
recombinant plasmid
with intact lacZgene
Colony carrying
recombinant
plasmid with
disrupted lacZgene
Bacterial
clone
-
8/7/2019 20 Lectures PPT
16/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Identifying Clones Carrying a Gene ofInterest
A clone carrying the gene of interest can beidentified with a nucleic acid probe having a
sequence complementary to the gene
This process is called nucleic acid hybridization
An essential step in this process is denaturation of
the cells DNA, separation of its two strands
-
8/7/2019 20 Lectures PPT
17/66
LE 20-5
Master plate
Filter
Solution
containing
probe
Filter liftedand flipped over
Radioactive
single-stranded
DNA
Probe
DNA
Gene of
interest
Single-stranded
DNA from cell
Film
Hybridization
on filter
Master plate
Colonies
containing
gene of
interest
A special filter paper
is pressed against
the master plate,
transferring cells to
the bottom side ofthe filter.
The filter is treated to break
open the cells and denature
their DNA; the resulting
single-stranded DNA
molecules are treated so thatthey stick to the filter.
The filter is laid
under photographic
film, allowing any
radioactive areas to
expose the film(autoradiography).
After the
developed film is
flipped over, the
reference marks
on the film andmaster plate are
aligned to locate
colonies carrying
the gene of
interest.
-
8/7/2019 20 Lectures PPT
18/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Storing Cloned Genes in DNA Libraries
A genomic library that is made using bacteria isthe collection of recombinant vector clones
produced by cloning DNA fragments from an
entire genome
A genomic library that is made using
bacteriophages is stored as a collection of phage
clones
-
8/7/2019 20 Lectures PPT
19/66
LE 20-6
Bacterialclones RecombinantplasmidsRecombinant
phage DNA
or
Foreign genomecut up with
restriction
enzyme
Phage
clones
Plasmid library Phage library
-
8/7/2019 20 Lectures PPT
20/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
A complementary DNA (cDNA) library is made bycloning DNA made in vitro by reverse transcription
of all the mRNA produced by a particular cell
A cDNA library represents only part of thegenomeonly the subset of genes transcribed
into mRNA in the original cells
-
8/7/2019 20 Lectures PPT
21/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Cloning and Expressing Eukaryotic Genes
As an alternative to screening a DNA library,clones can sometimes be screened for a desired
gene based on detection of its encoded protein
After a gene has been cloned, its protein productcan be produced in larger amounts for research
-
8/7/2019 20 Lectures PPT
22/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Bacterial Expression Systems
Several technical difficulties hinder expression ofcloned eukaryotic genes in bacterial host cells
To overcome differences in promoters and other
DNA control sequences, scientists usually employ
an expression vector, a cloning vector that
contains a highly active prokaryotic promoter
-
8/7/2019 20 Lectures PPT
23/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Eukaryotic Cloning and Expression Systems
The use of cultured eukaryotic cells as host cellsand yeast artificial chromosomes (YACs) as
vectors helps avoid gene expression problems
YACs behave normally in mitosis and can carry
more DNA than a plasmid
Eukaryotic hosts can provide the posttranslationalmodifications that many proteins require
-
8/7/2019 20 Lectures PPT
24/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
One method of introducing recombinant DNA intoeukaryotic cells is electroporation, applying a brief
electrical pulse to create temporary holes in
plasma membranes
Alternatively, scientists can inject DNA into cells
using microscopic needles
Once inside the cell, the DNA is incorporated into
the cells DNA by natural genetic recombination
-
8/7/2019 20 Lectures PPT
25/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Amplifying DNA in Vitro: The Polymerase ChainReaction (PCR)
The polymerase chain reaction, PCR, can producemany copies of a specific target segment ofDNA
A three-step cycleheating, cooling, andreplicationbrings about a chain reaction that
produces an exponentially growing population ofidentical DNA molecules
-
8/7/2019 20 Lectures PPT
26/66
LE 20-7
Genomic DNA
Target
sequence
5d
3d
3d
5d
5d
3d
3d
5d
Primers
Denaturation:
Heat brieflyto separate DNAstrands
Annealing:Cool to allowprimers to formhydrogen bondswith ends oftarget sequence
Extension:DNA polymeraseadds nucleotides tothe 3d end of eachprimer
Cycle 1yields
2molecules
New
nucleo-
tides
Cycle 2yields
4molecules
Cycle 3yields 8
molecules;2 molecules
(in white boxes)match target
sequence
-
8/7/2019 20 Lectures PPT
27/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Concept 20.2: Restriction fragment analysisdetects DNA differences that affect restriction sites
Restriction fragment analysis detects differencesin the nucleotide sequences ofDNA molecules
Such analysis can rapidly provide comparative
information about DNA sequences
-
8/7/2019 20 Lectures PPT
28/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Gel Electrophoresis and Southern Blotting
One indirect method of rapidly analyzing andcomparing genomes is gel electrophoresis
This technique uses a gel as a molecular sieve to
separate nuclei acids or proteins by size
Video: Biotechnology LabVideo: Biotechnology Lab
-
8/7/2019 20 Lectures PPT
29/66
LE 20-8
Cathode
Powersource
Anode
Mixtureof DNAmolecules
of differ-ent sizes
Gel
Glassplates
Longermolecules
Shortermolecules
-
8/7/2019 20 Lectures PPT
30/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
In restriction fragment analysis, DNA fragmentsproduced by restriction enzyme digestion of a
DNA molecule are sorted by gel electrophoresis
Restriction fragment analysis is useful forcomparing two different DNA molecules, such as
two alleles for a gene
-
8/7/2019 20 Lectures PPT
31/66
LE 20-9Normal F-globin allele
175 bp 201 bp Large fragment
Sickle-cell mutant F-globin allele
376 bp Large fragment
Ddel Ddel Ddel Ddel
Ddel Ddel Ddel
Ddel restriction sites in normal and sickle-cell alleles ofF-globin gene
Normalallele
Sickle-cellallele
Largefragment
376 bp201 bp
175 bp
Electrophoresis of restriction fragments from normaland sickle-cell alleles
-
8/7/2019 20 Lectures PPT
32/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
A technique called Southern blotting combines gelelectrophoresis with nucleic acid hybridization
Specific DNA fragments can be identified by
Southern blotting, using labeled probes that
hybridize to the DNA immobilized on a blot of gel
-
8/7/2019 20 Lectures PPT
33/66
LE 20-10
DNA + restriction enzyme Restrictionfragments
- NormalF-globinallele
-- Sickle-cellallele
--- Heterozygote
Preparation of restriction fragments. Gel electrophoresis. Blotting.
- -- --- Nitrocellulosepaper (blot)
Gel
Sponge
Alkalinesolution
Papertowels
Heavyweight
Hybridization with radioactive probe.
- -- ---
Radioactivelylabeled probe
forF-globingene is addedto solution ina plastic bag
Paper blot
Probe hydrogen-bonds to fragmentscontaining normalor mutant F-globin
Fragment fromsickle-cellF-globin allele
Fragment fromnormal F-globinallele
Autoradiography.
- -- ---
Film overpaper blot
-
8/7/2019 20 Lectures PPT
34/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Restriction Fragment Length Differences asGenetic Markers
Restriction fragment length polymorphisms(RFLPs, or Rif-lips) are differences in DNA
sequences on homologous chromosomes that
result in restriction fragments of different lengths
A RFLP can serve as a genetic marker for aparticular location (locus) in the genome
RFLPs are detected by Southern blotting
-
8/7/2019 20 Lectures PPT
35/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Concept 20.3: Entire genomes can be mapped atthe DNA level
The most ambitious mapping project to date hasbeen the sequencing of the human genome
Officially begun as the Human Genome Project in
1990, the sequencing was largely completed by2003
Scientists have also sequenced genomes of other
organisms, providing insights of general biological
significance
-
8/7/2019 20 Lectures PPT
36/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Genetic (Linkage) Mapping: Relative Ordering ofMarkers
The first stage in mapping a large genome isconstructing a linkage map of several thousand
genetic markers throughout each chromosome
The order of markers and relative distances
between them are based on recombination
frequencies
-
8/7/2019 20 Lectures PPT
37/66
LE 20-11
Cytogenetic map
Genes located
by FISH
Chromosome
bands
Genetic
markers
Genetic (linkage)
mapping
Physical mapping
Overlapping
fragments
DNA sequencing
-
8/7/2019 20 Lectures PPT
38/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Physical Mapping: Ordering DNA Fragments
A physical map is constructed by cutting a DNAmolecule into many short fragments and arranging
them in order by identifying overlaps
Physical mapping gives the actual distance in
base pairs between markers
-
8/7/2019 20 Lectures PPT
39/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
DNA Sequencing
Relatively short DNA fragments can be sequencedby the dideoxy chain-termination method
Inclusion of special dideoxyribonucleotides in the
reaction mix ensures that fragments of various
lengths will be synthesized
E 20 12
-
8/7/2019 20 Lectures PPT
40/66
LE 20-12
DNA(template strand)
5d
3d
Primer3d
5d
DNApolymerase
Deoxyribonucleotides Dideoxyribonucleotides(fluorescently tagged)
3d
5dDNA (templatestrand)
Labeled strands3d
Directionof movementof strands
Laser Detector
-
8/7/2019 20 Lectures PPT
41/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Linkage mapping, physical mapping, and DNAsequencing represent the overarching strategy of
the Human Genome Project
An alternative approach to sequencing genomes
starts with sequencing random DNA fragments
Computer programs then assemble overlapping
short sequences into one continuous sequence
LE 20 13
-
8/7/2019 20 Lectures PPT
42/66
LE 20-13
Cut the DNA from
many copies of an
entire chromosome
into overlapping frag-
ments short enough
for sequencing
Clone the fragments
in plasmid or phage
vectors
Sequence each fragment
Order the
sequences into one
overall sequence
with computer
software
-
8/7/2019 20 Lectures PPT
43/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Concept 20.4: Genome sequences provide clues toimportant biological questions
In genomics, scientists study whole sets of genesand their interactions
Genomics is yielding new insights into genome
organization, regulation of gene expression,
growth and development, and evolution
-
8/7/2019 20 Lectures PPT
44/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Identifying Protein-Coding Genes in DNASequences
Computer analysis of genome sequences helpsidentify sequences likely to encode proteins
The human genome contains about 25,000 genes,
but the number of human proteins is much larger
Comparison of sequences of new genes with
those of known genes in other species may help
identify new genes
-
8/7/2019 20 Lectures PPT
45/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
-
8/7/2019 20 Lectures PPT
46/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Determining Gene Function
One way to determine function is to disable thegene and observe the consequences
Using in vitro mutagenesis, mutations areintroduced into a cloned gene, altering or
destroying its function When the mutated gene is returned to the cell, the
normal genes function might be determined byexamining the mutants phenotype
In nonmammalian organisms, a simpler and fastermethod, RNA interference (RNAi), has been usedto silence expression of selected genes
-
8/7/2019 20 Lectures PPT
47/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Studying Expression of Interacting Groups ofGenes
Automation has allowed scientists to measureexpression of thousands of genes at one timeusing DNA microarray assays
DNA microarray assays compare patterns of gene
expression in different tissues, at different times,or under different conditions
LE 20-14
-
8/7/2019 20 Lectures PPT
48/66
LE 20-14
Make cDNA by reverse
transcription, using
fluorescently labeled
nucleotides.
Apply the cDNA mixture to amicroarray, a microscope slide
on which copies of single-
stranded DNA fragments from
the organisms genes are fixed,
a different gene in each spot.
The cDNA hybridizes with any
complementary DNA on the
microarray.
Rinse off excess cDNA; scan
microarray for fluorescent.
Each fluorescent spot
(yellow) represents a gene
expressed in the tissue
sample.
Isolate mRNA.Tissue sample
mRNA molecules
Labeled cDNA molecules(single strands)
DNA
microarray
Size of an actual
DNA microarray
with all the genes
of yeast (6,400 spots)
-
8/7/2019 20 Lectures PPT
49/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Comparing Genomes of Different Species
Comparative studies of genomes from related andwidely divergent species provide information in
many fields of biology
The more similar the nucleotide sequences
between two species, the more closely relatedthese species are in their evolutionary history
Comparative genome studies confirm therelevance of research on simpler organisms to
understanding human biology
-
8/7/2019 20 Lectures PPT
50/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Future Directions in Genomics
Genomics is the study of entire genomes
Proteomics is the systematic study of all proteins
encoded by a genome
Single nucleotide polymorphisms (SNPs) provide
markers for studying human genetic variation
-
8/7/2019 20 Lectures PPT
51/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Concept 20.5: The practical applications of DNAtechnology affect our lives in many ways
Many fields benefit from DNA technology andgenetic engineering
i i i
-
8/7/2019 20 Lectures PPT
52/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Medical Applications
One benefit ofDNA technology is identification ofhuman genes in which mutation plays a role in
genetic diseases
Di i f Di
-
8/7/2019 20 Lectures PPT
53/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Diagnosis ofDiseases
Scientists can diagnose many human geneticdisorders by using PCR and primers
corresponding to cloned disease genes, then
sequencing the amplified product to look for the
disease-causing mutation Even when a disease gene has not been cloned,
presence of an abnormal allele can be diagnosed
if a closely linked RFLP marker has been found
LE 20-15
-
8/7/2019 20 Lectures PPT
54/66
LE 20 15
DNA
RFLP marker
Disease-causing
allele
Normal allele
Restriction
sites
H G Th
-
8/7/2019 20 Lectures PPT
55/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Human Gene Therapy
Gene therapy is the alteration of an afflictedindividuals genes
Gene therapy holds great potential for treating
disorders traceable to a single defective gene
Vectors are used for delivery of genes into cells
Gene therapy raises ethical questions, such aswhether human germ-line cells should be treated
to correct the defect in future generations
LE 20-16
-
8/7/2019 20 Lectures PPT
56/66
Cloned gene
Retrovirus
capsid
Bone
marrow
cell from
patient
Inject engineered
cells into patient.
Insert RNA version of normal allele
into retrovirus.
Viral RNA
Let retrovirus infect bone marrow cells
that have been removed from the
patient and cultured.
Viral DNA carrying the normal
allele inserts into chromosome.
Bone
marrow
Ph ti l P d t
-
8/7/2019 20 Lectures PPT
57/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Pharmaceutical Products
Some pharmaceutical applications ofDNAtechnology:
Large-scale production of human hormones
and other proteins with therapeutic uses
Production of safer vaccines
F i E id
-
8/7/2019 20 Lectures PPT
58/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Forensic Evidence
DNA fingerprints obtained by analysis of tissueor body fluids can provide evidence in criminal and
paternity cases
ADNA fingerprint is a specific pattern of bands of
RFLP markers on a gel
The probability that two people who are notidentical twins have the same DNA fingerprint is
very small Exact probability depends on the number of
markers and their frequency in the population
LE 20-17
-
8/7/2019 20 Lectures PPT
59/66
Defendants
blood (D)
Blood from defendants
clothes
Victims
blood (V)
E i t l Cl
-
8/7/2019 20 Lectures PPT
60/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Environmental Cleanup
Genetic engineering can be used to modify themetabolism of microorganisms
Some modified microorganisms can be used to
extract minerals from the environment or degrade
potentially toxic waste materials
Agric lt ral Applications
-
8/7/2019 20 Lectures PPT
61/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Agricultural Applications
DNA technology is being used to improveagricultural productivity and food quality
Animal Husbandry and Pharm Animals
-
8/7/2019 20 Lectures PPT
62/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
AnimalHusbandry and PharmAnimals
Transgenic organisms are made by introducinggenes from one species into the genome ofanother organism
Transgenic animals may be created to exploit the
attributes of new genes (such as genes for fastergrowth or larger muscles)
Other transgenic organisms are pharmaceuticalfactories, producers of large amounts of
otherwise rare substances for medical use
-
8/7/2019 20 Lectures PPT
63/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Genetic Engineering in Plants
-
8/7/2019 20 Lectures PPT
64/66
Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Genetic Engineering in Plants
Agricultural scientists have endowed a number of
crop plants with genes for desirable traits
The Ti plasmid is the most commonly used vector
for introducing new genes into plant cells
LE 20-19A b t i t f i
-
8/7/2019 20 Lectures PPT
65/66
Agrobacterium tumefaciens
Ti
plasmid
Site where
restriction
enzyme cuts
DNA with
the gene
of interest
T DNA
Recombinant
Ti plasmid
Plant with
new trait
Safety and Ethical Questions Raised by DNA
-
8/7/2019 20 Lectures PPT
66/66
Safety and Ethical Questions Raised by DNATechnology
Potential benefits of genetic engineering must be
weighed against potential hazards of creating
harmful products or procedures
Most public concern about possible hazards
centers on genetically modified (GM) organismsused as food