Biotechnology and Society


22 Οκτ 2013 (πριν από 4 χρόνια και 6 μήνες)

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Biotechnology and Society

Prof. Arnaldo Ferreira

Keep In Mind

Biotechnology is an outgrowth of recombinant
DNA technology


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


Blood clotting factors, insulin

Provides a constant supply, uncontaminated by
causing agents

These proteins are made in bacteria, cell lines
from higher organisms, animals, and plants

Human Proteins

Can Be Made in Animals


The transfer of genes between species

Transgenic organism

An organism that has received a gene from
another species by means of recombinant DNA

Pompe Disease

Pompe disease

An inability to make
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

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 antibiotic
resistance genes used as markers?

Keep In Mind

Many crop plants have been genetically

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 15

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

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
fertilization, before embryo is implanted


Cell in early stages of embryonic development

Polar Body Biopsy

In a woman heterozygous for an X
disorder, the X chromosome with the mutant
allele segregates into a polar body

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
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

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

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


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

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

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