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Biotechnology and Society
Prof. Arnaldo Ferreira
Keep In Mind
 Biotechnology is an outgrowth of recombinant
DNA technology
 Biotechnology
• The use of recombinant DNA technology to
produce commercial goods and services
14.1 Biopharming: Making Medical
Molecules in Animals and Plants
 Genetic engineering is used to manufacture
proteins used in treating human diseases
• Examples: Blood clotting factors, insulin
• Provides a constant supply, uncontaminated by
disease-causing agents
 These proteins are made in bacteria, cell lines
from higher organisms, animals, and plants
Human Proteins
Can Be Made in Animals
 Transgenic
• The transfer of genes between species
 Transgenic organism
• An organism that has received a gene from
another species by means of recombinant DNA
technology
Pompe Disease
 Pompe disease
• An inability to make α-glucosidase (GAA)
• Treated by enzyme replacement therapy
 Transgenic animals produce human GAA
• Transgenic female rabbits produce human GAA
enzyme in their milk
• Human GAA produced in transgenic hamster
cells
14.2 Genetically Modified Foods
 Gene transfer into crop plants confers resistance
to herbicides, insect pests, and plant diseases
• Also used to increase the nutritional value of
foods (such as vitamin A)
 Genetically modified organisms (GMOs)
• A term referring to transgenic plants or animals
Genetically Modified Foods
 60% to 70% of foods in US supermarkets
contain some transgenic plant material
 Products made from corn, soybeans, cottonseed
and canola oils most commonly contain
transgenic ingredients
Transgenic Crops
Used to Enhance Nutrition
 Golden rice increases vitamin A
• Genes from daffodils, corn, and bacteria
Concerns About
Genetically Modified Organisms
 Are foods containing new proteins safe to eat?
 Is it safe to eat food carrying part of a viral gene
that switches on transgenes?
 Will pesticide-resistant insects develop?
 Will disease-causing bacteria acquire antibioticresistance genes used as markers?
Keep In Mind
 Many crop plants have been genetically
modified
14.3 Transgenic Animals
as Models of Human Diseases
 Transfer of disease-causing human genes
creates transgenic organisms that are used to
study the development of human diseases and
the effects of drugs and other therapies as
methods of treating these disorders
HD Mice as Models
 HD mice are extremely useful as models of
human neurodegenerative disorders
• Used to study the progressive destruction of brain
structures in early disease stages
• Used to link changes in brain structure with
changes in behavior
• Used to screen drugs to improve symptoms or
reverse brain damage
Transferring Genes into Mammals
 Microinjection of fertilized eggs
14.4 Testing for Genetic Disorders
 Genetic testing
• Used to determine if someone has a genotype for
a genetic disorder or is a carrier
• Identifies individuals with a particular genotype
 Genetic screening
• Systematic search for individuals in a population
who have certain genotypes
• Tests general populations that may have a low
frequency for a disorder
Four Types of Testing Programs
 Newborn screening
 Carrier testing
 Prenatal testing
 Presymptomatic (predictive) testing
Newborn Screening in the US
 Newborn screening tests infants within 48 to 72
hours after birth for a variety of genetically
controlled metabolic disorders
 All states require newborns to be tested
• Most states screen for 3 to 8 disorders
• New methods can scan for 30 to 50 disorders
Carrier and Prenatal Testing
Screen for Genetic Disorders
 Carrier testing searches for heterozygotes that
may be at risk of producing a defective child
• Done on family members or cultural groups with a
history of a genetic disorder such as sickle cell
anemia or cystic fibrosis
 Prenatal testing tests a fetus for genetic
disorders (e.g. cystic fibrosis) or chromosome
abnormalities (e.g. Down syndrome)
Methods of Prenatal Testing
 Amniocentesis can be done after the 15th week
of development
 Chorionic villus sampling (CVS) is usually done
at 10 to 12 weeks of development
Prenatal Testing
Can Diagnose Sickle Cell Anemia
 Recombinant DNA-based prenatal testing can
detect genetic disorders that cannot otherwise
be detected before birth
 Sickle-cell beta globin genes have a distinctive
pattern of banding on a Southern blot
• Normal gene: Two small fragments
• Sickle gene: One large fragment
Prenatal Genetic Diagnosis (PGD)
Can Test Embryos for Genetic Disorders
 Testing can be done on blastomeres from in
vitro fertilization, before embryo is implanted
 Blastomere
• Cell in early stages of embryonic development
Polar Body Biopsy
 In a woman heterozygous for an X-linked
disorder, the X chromosome with the mutant
allele segregates into a polar body or an oocyte
Prenatal Testing
is Associated with Some Risks
 Risks for mother and fetus
• Infection, hemorrhage, fetal injury, and
spontaneous abortion
 Risk of miscarriage
• Amniocentesis: 0.5% to 1.0%
• CVS: 1% to 3%
Cystic Fibrosis: Testing For 25 Mutations
in Different Ethnic Groups
 With over 1,500 mutations identified, it is not
possible to test for all cases
Presymptomatic Testing
Can Be Done for Some Genetic Disorders
 Presymptomatic testing (predictive testing)
identifies some individuals who will develop
adult-onset genetic disorders
• Huntington disease
• Polycystic kidney disease (PCKD)
Genetics in Society:
Who Owns a Genetic Test?
 Families of children with Canavan disease, a
rare and fatal disorder, started a foundation to
obtain tissue samples and funding for research
 The research hospital patented the gene and
charged participating families for the test
 After a lawsuit, the hospital was allowed to
continue to license the test and collect royalties
Keep In Mind
 Genetic disorders can be diagnosed using
biotechnology
14.5 DNA Microarrays in Genetic Testing
 Testing for a wide range of genetic disorders is
possible using DNA chips (microarrays), which
can hold thousands of genes
 DNA microarray
• A series of short nucleotide sequences placed on
a solid support (such as glass) that have several
different uses
Uses of Microarray Technology
 Detecting mutant genes
• Individuals who will develop late-onset genetic
disorders such as polycystic kidney disease
(PCKD) and Huntington disease
• Individuals at risk for disorders such as diabetes
 Detecting differences in the pattern of gene
expression in normal and cancerous cells
Microarray Testing
 Each field of the microarray contains a unique
sequence of single-stranded DNA
 Test DNA and normal DNA are converted to
single strands, tagged with fluorescent dyes, and
hybridized to the chip
 Each result has a different color
• Normal alone is green; mutant alone is red
• Both together are yellow; a blank field is black
Reading a Microarray Field
 The tumor-suppressor gene p53
14.6 DNA Profiles
as Tools for Identification
 DNA profiles use variations in the length of short
repetitive DNA sequences to identify individuals
with a high degree of accuracy and reliability
 This method is used in many areas, including
law enforcement, biohistory, conservation, and
the study of human populations
DNA Fingerprints
 Minisatellites
• Nucleotide sequences 14 to 100 base pairs long
organized into clusters of varying lengths; used in
the construction of DNA fingerprints
 DNA fingerprint
• Detection of variations in minisatellites used to
identify individuals
DNA Profiles
 Short tandem repeats are now used routinely
instead of minisatellites, and DNA profile has
replaced the term DNA fingerprint
 Short tandem repeat (STR)
• Short nucleotide sequences 2 to 9 base pairs
long organized into clusters of varying lengths
 DNA profile
• STR pattern used to identify individuals
DNA Profiles Can Be Made from
Short Tandem Repeats (STRs)
 STRs range from 2 to 9 base pairs in length
• CCTTCCCTTCCCTTCCCTTCCCTTCCCTTC
contains six repeats of the CCTTC sequence
 Repeat numbers vary between individuals
• A unique profile can be produced by analyzing
several STRs in a DNA sample
• In the US, a standard set of 13 STRs (CODIS) is
used to prepare a profile
DNA Profiles Are Used in the Courtroom
 Analysis of DNA profiles combines probability
theory, statistics, and population genetics to
estimate how frequently an allele combination is
found in a population
 Population frequencies for STRs are multiplied
together to produce an estimate
Analyzing DNA Profiles
 One suspect matches the crime scene evidence
Keep In Mind
 DNA profiles are based on variations in the copy
number of DNA sequences
Other Uses for DNA Profiles
 Two littermates, one a pure Shih Tzu, the other
a mixed breed
Genetic Journeys: Death of a Czar
 Forensics and several types of DNA evidence
were used to confirm that bones discovered in
1991 belonged to Czar Nicholas Romanov II, his
wife, and three of their five children
14.7 Social and Ethical
Questions about Biotechnology
 Applications of recombinant DNA technology
have developed faster than societal consensus,
public policy, and laws governing its use
 Efforts to inform legislators, members of the
legal and medical profession, and the public
often have lagged behind its commercial use
• A balanced approach requires education and
debates on risks and benefits
Keep In Mind
 The uses of biotechnology have produced
unresolved ethical issues