Download Genetic Engineering

A look at the world today
Genetic Engineering
(Bilingual Program)
Fall, 2010
He, Xiaoyang
Dr. Li, Hui
Dr. Tian, Shengli
Scope

Introduction and Molecular Tools



Introduction
Enzymes
vectors

Recombinant DNA Technology

The study of Gene Expressions

Modern Methods in Molecular Biology
Schedule
第一章
绪 论
Introduction
2
第二章
基因工程的工具酶
Enzymes
4
第三章
基因工程载体
Vectors
4
第四章
目的基因的获得
2
第五章
基因与载体的体外连接
2
第六章
重组DNA分子导入受体细胞
4
第七章
含目的基因重组体的筛选、鉴定与分析 5
第八章
目的基因的表达
6
第九章
基因工程药物无性繁殖系的组建
3
第十章
基因工程抗体
4
Reading
基因工程
彭银祥等主编
武汉：华中科技大学出版社 ©2006
Gene Cloning and DNA Analysis: An Introduction
By Terry A. Brown
English Vs. Chinese (PDF)
Molecular Biology (Instant Notes, 3rd edition)
By Phil Turner, Alexander Mclennan, Andy Bates & Mike White
北京: 科学出版社，2009
References

Molecular Cloning A laboratory
manual(Third Edition)
Sambrook & Russell Cold Spring Harbor Laboratory
Press c2001

《分子克隆实验指南》第三版
【作
者】（美）萨姆布鲁克等著 金冬雁等译
【出 版 社】 科学出版社

Molecuolar Biology ( 4th edition )
Robert F. Weaver
New York: McGraw Hill Higher Education, c2008

Principles of Gene Manipulation
S. B. Primrose, Richard M. Twyman
Goals
• Groundwork for understanding the experimental
and conceptual basis of gene cloning and DNA
manipulation
• Principles of genetic engineering
• Powerful experimental tools and strategies
• New discoveries and new methodologies
• Perspectives in the literature
• Perspectives for the future
Evaluation


Attendance 10%
Assignments 20 ～ 30 %
1. Select a company that sale any biotech products that
you like. Then, write a “product review” describing
this product in as much detail as possible but no more
than one A4 page （or team work presentation？）。

Exam 70 ～ 60 %
Close book, 2 hrs.
考试与成绩评定方式
学期总成绩包括出勤、平时成绩和期末考试成绩三部分组成。平时记
录的出勤情况、课堂提问、以及课后作业等占30％，期末成绩占70％。
Chapter 1
Introduction
Overview
1.1
1.2
1.3
1.4
Gene and Genetic Engineering
A Brief History
Applications
Safety and Ethical Discussions
(伦理学的）
第一章 绪论
教学目的、要求：
1.掌握基因工程的基本概念与研究内容
2.了解基因工程发展简史及与基因工程发展有密切关系的的关键事件
3.了解现代生物技术与基因工程的研究内容和发展趋势
教学内容：
1、基因工程的概念
2、基因工程的发展史
3、基因工程的应用
4、基因工程的安全性与伦理学问题
1.1 Gene and Genetic Engineering
1.1.1 Review
Gene: A gene is a basic unit of heredity（遗传）
in a living organism. It is "a locatable region of
genomic sequence, corresponding to a unit of
inheritance, which is associated with regulatory
regions, transcribed regions, and or other
functional sequence regions “. [1]
Coding for proteins
3 classes of genes Coding for RNAs
Specific functions
Genes hold the information to build and maintain
an organism's cells and pass genetic traits to
offspring. [2]
1. Pearson H (2006). "Genetics: what is a gene?". Nature 441 (7092): 398–401
2. http://en.wikipedia.org/wiki/Gene
Allele(等位基因): Each gene can have different
alleles. An allele (from the Greek αλληλος allelos,
meaning each other) is one of two or more forms
of the DNA sequence of a particular gene.
Diploid （二倍体）； Triploid （三倍体）；etc.
The vast majority of living organisms encode their
genes in long strands of DNA. The most common
form of DNA in a cell is in a double helix structure
RNA is common as genetic storage material in
viruses, in mammals in particular RNA inheritance
has been observed very rarely.
Central Dogma of Molecular Biology: The flow of
genetic information in the cell starts at DNA, which
replicates to form more DNA. Information is then
‘transcribed” into RNA, and then it is “translated”
into protein. The proteins do most of the work in
the cell. Once information gets into protein, it can't
flow back to nucleic acid.
Gene
Material
DNA/RNA
Function
Nature
Peptide coding
Reproducible
RNA transcripts
Movable
Regulatory unit
Mutagenicity
Reconstructible
……
1.1.2 Definition of Gentic Engineering
GE: The technology entailing(承担) all
processes of altering the genetic
material of a cell to make it capable of
performing the desired functions, such
as producing novel substances.
In other words:
Genetic engineering is the deliberate(深
思熟虑的), controlled manipulation(操纵,篡
改)of genes in an organism in order to
upgrade that organism.
1.2 A Brief History of Genetic Engineering
Some major steps in the development of GE
Theoretic
basis
Identification of DNA as the genetic material
DNA double helix
Central dogma
Tools & Tech
breakthroughs
DNA manipulative enzymes
DNA sequencing
PCR
Plasmid Vector
Libraries
Bioinformatics
Animal Cloning w/t Nuclear Transfer
……
Steps marked the beginning of a new age in biology
Rediscovery of
Mendel's laws helps
establish the science
of genetics
Huntington
DNA recombination
disease gene
mapped to
& delivery method chromosome 4
1900
1972
1953
Watson and Crick
identify DNA
(the double helix) as
the Chemical basis
of heredity
Genetic and
physical
mapping
1983
1980
DNA markers used
to map human
disease genes to
chromosomal
regions
1994-98
1990
Human Genome
Projects (HPG)
begins-an
international
effort to map and
sequence all the
genes in the
human genome
1998
Working Draft of
the human
genome
sequencing
complete
2000
2005
(or earlier)
DNA markers used
to map human
disease genes to
chromosomal
regions
Gene map
expected to
be complete
Health Policy Research Bulletin, volume 1 issue2, September 2001
1.2.1 Some major steps in the development of GE
http://www.nature.com/milestones/miledna/timeline.html
2003
2005
2006
mRNA)
Finished the sequence of human genome
Finished the sequence of chimpanzee genome
Craig C. Mello and Andrew Fire's received a noble prize for RNAi (1998 discovered RNAi degrading
1.2.2 People, Events & Theoretical basis
Identification of DNA as the genetic material
Factors carryout the genetic messages?
locating on the chromatins/chromosomes
chromosomes consist of DNA and proteins
Which one is the genetic material?
Traits ------- Heredity
From Mendel to Avery
Mendelian Inheritance
Parents contribute specific particles (genetic units)
to their offspring. ----Implication of gene
Genes can exist in several different forms, or
alleles.
One allele can be dominant over another, so
heterozygotes having two different alleles of one
Gene will f nerally exhibit the characteristic
dictated by the dominant allele. The recessive allele
is not lost; it can still exert its influence when pairs
with another recessive allele in a homozygote.
Johan Friedrich Miescher Swiss Biologist
Isolated nuclei of white blood cells in 1869
 The major component of “nuclein” is DNA
 Protein is the other major component of nuclein
 Led to identification of nucleic acid by Walter
Flemming
 DNA and RNA are both nucleotide polymers



Walter Sutton
Determined in 1903 that chromosomes carried
units of heredity identified by Mendel
Wilhelm Johannsen Danish Botanist
Named “genes” in 1909
Thomas Hunt Morgan
Studied genetics of fruit flies in early 1900’s

Experimented with eye color

Eye color phenotype was sex-linked
His work contributed to the knowledge of X and
Y chromosomes

Nobel Peace Prize in 1933 for research in gene
theory

The Chromosome Theory of Inheritance
Genes are arranged in linear fashion on
chromosome. The reason that certain traits tend
to be inheritated together is that the genes
governing these traits are on the same
chromosome.
Every gene has its place (locus)
Diploid organism (human) normally have two
copies of all chromosomes (except sex
chromosomes)
DNA recombination occurs in nature
Griffith’s Transformation Experiment

The discovery of the genetic role of DNA in 1928

two strains of a bacterium, a pathogenic(致病性)
“S” and a harmless “R”

mixed heat-killed remains of the pathogenic strain
with living cells of the harmless strain, some living
cells became pathogenic

He called this phenomenon transformation, now
defined as a change in genotype and phenotype
due to assimilation(同化作用) of foreign DNA
Living S cells
(control)
Living R cells
(control)
Heat-killed
S cells (control)
Mixture of heat-killed
S cells and living R cells
RESULTS
Mouse dies
Mouse healthy
Mouse healthy
Mouse dies
Living S cells
are found in
blood sample
Challenges: “principle “ transform the R into S with smooth
coat?
Oswald Avery and Colin Macleod

In 1944, Oswald Avery, Maclyn McCarty, and
Colin MacLeod announced that the transforming
substance was DNA

Their conclusion was based on experimental
evidence that only DNA worked in transforming
harmless bacteria into pathogenic bacteria

Many biologists remained skeptical, mainly
because little was known about DNA

Led by the earlier experiment of transfer genetic
trait from one train of bacteria to another
Avery’s Transformation Experiment
Identity the “principle”
Animation: http://www.dnaftb.org/dnaftb/17/animation/animation.html
Hershey-Chase Bacteriophage Experiment




In 1952, Alfred Hershey and Martha Chase
performed experiments showing that DNA is
the genetic material of a phage known as T2
To determine the source of genetic material in
the phage, they designed an experiment
showing that only one of the two components
of T2 (DNA or protein) enters an E. coli cell
during infection
32P is discovered within the bacteria and
progeny(子代) phages, whereas 35S is not
found within the bacteria but released with
phage ghosts(衣壳).
They concluded that the injected DNA of the
phage provides the genetic information
http://glencoe.mcgrawhill.com/sites/9834092339/student_view0/chapter14/hershey_and_chase_experiment
.html
Phage
Radioactive
protein
Empty
protein shell
Radioactivity
(phage protein)
in liquid
Bacterial cell
Batch 1:
Sulfur (35S)
DNA
Phage
DNA
Labeled
Pr shell
Centrifuge
Pellet (bacterial
cells and contents)
Radioactive
DNA
Batch 2:
Phosphorus (32P)
Labeled
DNA
Core
Centrifuge
Pellet
Radioactivity
(phage DNA)
in pellet
Additional Evidence That DNA Is the Genetic Material

1947: Erwin Chargaff- DNA composition varies from one
species to the next

By 1950s: DNA is a polymer of nucleotides, G=C, A=T

Franklin’s X-ray crystallographic images of DNA enabled
Watson and Crick to deduce that DNA was helical


The X-ray images also enabled Watson and Crick to
deduce the width of the helix and the spacing of the
nitrogenous bases

The width suggested that the DNA molecule was made
up of two strands, forming a double helix
Double Helix Model of DNA Structure
James Watson and Francis Crick
Collaborated at Cambridge University and
presented the double helix model of DNA
structure in 1953
 Described DNA dimensions and spacing of base
pairs
 Had major impact on genetic engineering carried
out today



1958, 1970 Crick: Central Dogma
1988, Watson: Principle scientist of the HGP
Central Dogma
Meselson-Stahl
DNA must replicate during each cell division
1958 DNA replication: semiconservative model
Nirenberg, Ochoa, Khorana
1966 genetic code elucidation
Meselson-Stahl Experiments

Labeled the nucleotides of old strands with a
heavy isotope of nitrogen (15N), new nucleotides
were indicated by a lighter isotope (14N).

The first replication in the 14N medium produced a
band of hybrid (15N-14N) DNA, eliminating the
conservative model.

A second replication produced both light and
hybrid DNA, eliminating the dispersive model and
supporting the semiconservative model.
http://highered.mcgraw-hill.com/olc/dl/120076/bio22.swf
Bacteria
cultured in
medium
containing
Bacteria
transferred to
medium
containing
15N
14N
Tech supports
DNA sample
centrifuged
after 20 min
(after first
replication)
DNA sample
centrifuged
after 40 min
(after second
replication)
Less
dense
Radio labelling
More
dense
First replication
Conservative
model
Semiconservative
model
Dispersive
model
Second replication
Ultracentrifuge
Synchronization
1.2.3 Molecular tools and
Technological breakthroughs
Enzymes- nucleic acid cleavage, ligation, ……
 Vector- molecular cloning
 Polymerase chain reaction
 DNA sequencing
 Electrophoretic separation
 Detection of genes:
DNA-Southern blotting; in situ hybridization;
FISH technique;
RNA- Northern blotting
Pr-Western blotting; inmmunohistochemistry
 Purification
 Transgenetic organisms
……

Discovery of DNA ligase
----the dawn of DNA manipulation
DNA recombination happens in the
cell — for example, when breaks
caused by UV are repaired
•
• search for an enzyme that could
join DNA molecules
In this illustration,
DNA ligase (in color)
encircles the
DNAdouble helix.
• 1967: The first DNA ligase was
purified and characterized in
different labs.
Enzymatic breakage and joining of deoxyribonucleic acid, I. Repair
of single-strand breaks in DNA by an enzyme system from
Escherichia coli infected with T4 bacteriophage" , PNAS 57: 10211028. 1967
Making the Cut
----discovery of the restriction enzymes
Hamilton Smith and Kent Wilcox
• 1970: isolation/characterization of endonuclease
R (HindII) from extracts of Haemophilus influenzae
(嗜血杆菌)strain Rd.
• the enzyme degraded foreign DNA, such as that
of phage T7, but did not affect native H. influenzae
DNA.
• proposed that the enzyme recognizes a specific
sequence on the foreign DNA,
The 'recombination' potential of restriction
enzymes was first demonstrated by Janet Mertz
and Ronald Davis.
They showed that the R1 restriction
endonuclease produces ‘staggered‘(参差)
breaks, generating ’cohesive’ ends that are
identical and complementary(互补).
Their findings suggested that any R1-generated
ends can be joined by incubation with DNA
ligase to generate hybrid DNA molecules.
Thus, the era of recombinant DNA technology
was born.
key concept :
Use of plasmid as vector for shuttling DNA into bacteria
1973, Stanley Cohen and his Stanford colleague Annie
Chang, in collaboration with Herbert Boyer and Robert
Helling at the University of California in San Francisco,
reported the first in vitro construction of a bacterial
plasmid.
Using EcoR I, they generated fragments from two
plasmids (each conferring resistance to one antibiotic),
joined them using DNA ligase and applied the mixture to
transform E. coli. As they had hoped, a fraction of the
transformed bacteria became resistant to both antibiotics
while carrying a single hybrid plasmid.
Not only had they demonstrated that bacterial plasmids
constructed in vitro were functional in bacteria, but they
had also described the first plasmid vector.
Paul Berg had devised(设计) a similar experiment
to transfer foreign DNA into mammalian cells,
using the tumour virus SV40 as a vector.
In 1972, he made a hybrid molecule in vitro by
inserting phage sequences into SV40. These
reports immediately raised concerns, as E. coli,
which is a natural habitant of the human gut,
could now carry hybrid DNA molecules containing
SV40 oncogenes(致癌基因) or other potentially
harmful sequences.
These fears led the community to a self-imposed
moratorium(暂停) on recombinant DNA
experiments. However, the foundation had been
laid and progress soon resumed.
Discovery of reverse transcriptase
——Full-length cDNA technologies
puzzle: the ability of RNA tumour viruses to stably
transform cells without incorporation of a DNA
copy of viral genes into the host genome
Baltimore, Temin and Mizutani, looked for DNA
polymerase activity in purified preparations of such
viruses.
DNA was being synthesized in RNA-dependent
way.
Baltimore, D. RNA-dependent DNA polymerase in virions of RNA tumour
viruses. Nature 226, 1209–1211 (1970)
reverse transcriptase could be used in vitro to
synthesize cDNA from mammalian mRNAs.
Verma et al. and Kacian et al. both added
preparations of glob in mRNAs to reverse
transcriptase from avian myeloblastosis virus. They
correctly hypothesized that the reaction would only
work efficiently if they also added oligo (dT)
Reverse transcription has become hugely
important in molecular biology. Its influence
extends from cloning to the development of
microarrays to the annotation of genomes.
DNA Libraries: YACs and BACs
1987, 1992
A vector carrying a 50-kb insert was far too small to
also contain all regulatory regions.
constructing comprehensive libraries covering the
whole genomes of higher organisms.
Maynard Olson and colleagues exchanged the E.
coli plasmid for a yeast artificial chromosome
(YAC): a linear DNA molecule that mimics a yeast
chromosome, complete with centromere and
telomeres.
YAC problems: chimaeras of noncontiguous DNA fragments;
inserts unstable; purification of YACs proved challenging
Challenge: combination of the plasmid simplicity
and stability with the aim of adapting it for largefragment cloning.
A group led by Melvin Simon modified an
endogenous circular plasmid in E. coli, the fertility
(F) factor present at one or two copies per cell, to
create a cloning vector.
In reference to its yeast cousin, they called it
bacterial artificial chromosome (BAC). With a
cloning capacity of 300 kb, BACs are not as potent
as YACs, but they have all the advantages of a
bacterial vector: stability, and ease of manipulation
and purification.
The basic steps in gene cloning
.
Gene Cloning and DNA Analysis by T.A. Brown. © 2006 T.A. Brown.
Cloning allows individual fragments of DNA to be purified.
Gene Cloning and DNA Analysis by T.A. Brown. © 2006 T.A. Brown.
1.3 Genetic Engineering Applications
Genetic Engineering of Bacteria and Fungi
a.
Drugs, Vaccines, & Antibiotics
b.
c.
Food Products (e.g., cheese)
Metabolism & Biofuel Production
d.
e.
Human Gene Delivery Systems
Fermentation & Alcoholic Beverages
Genetic Engineering of Animals & Plants
a.
b.
Biopharming (growing transgenic crops to produce
pharmaceutical products: drugs, vaccines, proteins)
Using Animals to Make Drugs
c.
Transgenic Crops: corn, soybean, cotton
Genetic Engineering of Humans
a.
b.
Germ Cell vs. Somatic Cell Gene Therapy
In Vivo Gene Therapy
c.
d.
Ex Vivo Gene Therapy
Cloning, Stem Cells, & Gene Therapy
The Industry of GE…
The most profit… ?
1980 - the U.S. patent for cloning genes is awarded
to Cohen and Boyer**

First biotech companies formed:
1976 – Genentech (Boyer)
1978 - Biogen
1980 - Amgen
1981 - Immunex
1981 - Chiron
1981 - Genzyme
1.3.1 Agricultural Applications

First food made by recombinant DNA technology
– Flavr Savr Tomatoes (1994)

60% of foods are genetically modified

Solution to world hunger
One change in DNA sequence (mutation)
can have a significant effect
A 601 ACGGTGCCCG CAAAGTGTGG CTAACCCTGA ACCGTGAGGG
B 601 ACGGTGCCCG CAAAGTGTGG ATAACCCTGA ACCGTGAGGG
+
Protein + Herbicide (除草剂）
A
Herbicide resistant
B
Herbicide sensitive
In the process of causing crown gall disease,
the bacterium A. tumefaciens inserts a part of
its Ti plasmid — a region called T-DNA —
into a chromosome of the host plant.
The only vectors routinely used to produce transgenic plants are
derived from a soil bacterium called Agrobacterium tumefaciens.
This bacterium causes what is known as crown gall disease, in
which the infected plant produces uncontrolled growths (tumors, or
galls), normally at the base (crown) of the plant. The key to tumor
production is a large (200-kb) circular DNA plasmid — the Ti
(tumor- inducting) plasmid. When the bacterium infects a plant
cell, a part of the Ti plasmid — a region called T-DNA — is
transferred and inserted, apparently more or less at random, into
the genome of the host plant
The functions required for this transfer are outside the T-DNA on
the Ti plasmid. The T-DNA itself carries several interesting
functions, including the production of the tumor and the synthesis
of compounds called opines. Opines are actually synthesized
to the host plant under the direction of the T-DNA. The
bacterium then uses the opines for its own purposes, calling on
opine-utilizing genes on the Ti plasmid. Two important opines
are nopaline and octopine; two separate Ti plasmids produce
them.
Genetically Engineered Crops
3 Types of Resistance
• Herbicide Resistance (HR)
– Most U.S. crops engineered with resistance to
glyphosate
• Insect Resistance (IR)
– Types of soil bacterium (Bacillus thuringiensis)
introduced into plant to target susceptible
insects
• Virus Resistance
The Impact of Genetically Engineered Crops on Farm Sustainability in the United States
Division on Earth and Life Study,The National Academes, US April 13, 2010
Genetically Engineering Crops
Nationwide acreage of GE soybean, corn, and cotton as a
percentage of all acreage of these crops
100
Percent GE crops
80
60
40
All GE Corn Varieties
All GE Cotton Varieties
20
All GE Soybean Varieties
0
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
Year
Source: USDA-NASS (2001, 2003, 2005, 2007, 2009b).
• Soybeans
– Herbicide resistance
• Corn
– Herbicide resistance
– Insect resistance
• Cotton
– Herbicide resistance
– Insect resistance
•
Oilseed Rape
Herbicide resistance
Insect resistance
Research has mainly focused upon 2 herbicides: glyphosate
(Monsanto's Roundup) and glufosinate (Hoechst's Challenge).
1.3.2 Biotechnology and the Environment
Waste
• Solid: landfills, combustion-including wasteto energy plants, composting
• Liquid: septic(腐烂物): sewage treatment
• Gas: fossil fuels, chlorofluorocarbons
• Hazardous –anything that can explode,
catch fire, release toxic fumes, and particles
or cause corrosion
Biotechnology and the Environment
Garbage Test
Banana Peel
 Wood Scrap/Sawdust
 Wax Paper
 Styrofoam Cup
 Tin Can
 Aluminum Soda Can
 Plastic Carton
 Glass Bottles

0.5 Years
 4 Years
 5 Years
 20 Years
 100 Years
 500 Years
 500 Years
 >500 Years

Biogeochemical Cycles are a major part of the
recycling process

Carbon Cycle: The primary biogeochemical cycle
organic cmpds  CO2 and back

Nitrogen Cycle: proteins amino acids NH3NO2NO3-NO2-N2ON2 NH3 etc_

Sulfur Cycle: Just like the nitrogen cycle, numerous
oxidation states. Modeled in the Winogradsky column

Phosphorous Cycle: Doesn’t cycle between numerous
oxidation states only soluble and insoluble form
There is no waste in Nature:

From rocks and soil to plants and animals to air
and water and back again:
Recycled largely by
Microbes
Bioremediation Basics
biodegradation
• Aerobic
• Oxygen is reduced to water
and the organic molecules
(e.g. petroleum, sugar) are
oxidized
• Anaerobic
• An inorganic compound is
reduced and the organic
molecules are oxidized (e.g.
nitrate is reduced and
sugar is oxidized)
• NOTE: Many microbes can do
both aerobic and anaerobic
respiration; the process which
produces the most ATP is used
first!
Some microorganism of the genera（种属） Nocardia and
Pseudomonas can grow in the environment where the
hydrocarbons are the only source of food. These bacteria
oxidize straight chain aliphatic hydrocarbon such as octane
to their corresponding carboxylic acids:
E?
CH3(CH2)6CH3 +NAD+ O2——– CH3(CH2)6COOH +
NADH + H+
China uses oil-eating bacteria to clean up spill
Tue Jul 20, 12:09 pm ET
BEIJING (AFP) – Authorities in China are using over 23 tones of
oil-eating bacteria to help clean up an oil spill in the Yellow Sea
caused by a pipeline explosion and fire at the weekend, state
media said Tuesday.
Petroleum spill in Gulf of Mexico?
1.3.3 Human & Medical Applications
Production of Insulin
 Genetic Screening/Testing
 Production of experimental mice, oncomouse
(cancer mouse)
 Transgenic animals
 Stem cells
……

Your thinking on biotech companies in
Shenzhen?
Cloning and Stem Cells




Clone created from one cell – not sex cell
Cloning – process of creating an identical copy of
an original (Example: Identical Twins)
Stem cells (master cells) can develop into any
tissue
Cure their own disease or build new organs – NO
REJECTION
Stem Cell Differentiation
Zygot
Adult
Five Day Pre-Embryo
http://www.nationalgeographic.com/ngm/
in vivo
ex-vivo
1.4 Safety and Ethic Issues
Facts about GE

The result is called genetically modified organism
(GMO)

One of the major aims is to produce much food at low
cost to reduce the world hunger

Conglomerates are buying up (收购) biotech start-up
companies, seed companies, agribusiness and
agrochemical concerns, pharmaceutical, medical and
health businesses, and food and drink companies
creating life sciences complexes to fashion bio-industrial
world

Can potentially be used in humans to change their
appearance, intelligence, character and adaptability
Pros & Cons of GE
Is GE precise enough ?
Pro arguments:

Scientits use „gene
guns“ to insert the
specific gene in the
organism precisely
Contra arguments:

The choice of gene is
precise. But the
insertion of this gene
into a living cell is
imprecise. There is no
control where in the
DNA the new gene is
inserted. This process
can disrupt the DNA
Pros & Cons of GE
Is Genetic Engineering safety?
Pro arguments
Contra arguments

All genetically engineered
foods have been
thoroughly tested and
demonstrated to be safe
before they are released
into the marketplace

Tests are only conducted on
animals like rats and mice.
Apart from that the
scientists are often not
independent due to the fact
that they are involved into
the big companies

Genetically engineered
foods have been sold in
the United States for
several years and it is no
evidence to indicate that
these foods have harmed
human health in any way

The consequences are now
unknown and unanticipated

The consequences for the
human health can only be
assessed after human
testing.
Pros & Cons of GE
Effects on the environment
Pro arguments:

GE minimizes
soil erosion by
reducing the need
of flowing .

Plants resisant to
weather , climate
insect infestation,
desease, molds
and fungi.
Contra arguments:

Every genetically engineered
organism released into the
environment is a threat to the
ecosystem because they are
unpredictable by interacting
with other living things in the
environment, therefore it is
difficult to assess the threats
of genetically engineered
organisms to the ecosystem.

GE can create toxins, noxiousvegetation, harm to wild life
and may create new molds
and fungi.
Pros & Cons of GE
Effects on the evironment
Pro arguments:

GE allows the
creation of thousands
of novel life forms in
a brief moment.
Contra arguments:
 Once GMOs are
released into the
environment they
cannot be recalled
therefore they are a
very dangerous kind
of pollution.
Pros & Cons of GE
Effects on the agriculture
Pro arguments:
 Farmers can spray in
order to kill weeds
without killing the
crops.
Contra arguments:
 Furthermore the
weeds might develop
their spray resistance
and greater herbicide
resistance has to be
created.
 The virus-resistance
might also create new
viruses that never
existed before.
Pros & Cons in general
Genetic engineering
reduces costs of
production This
means that the poor
can afford more food
 Cheaper and safer
source of human
medicine
 Higher productivity
 GE can reduce the
World hunger




GE is unnatural
GE crosses species
barriers which would
never occur in nature
A high danger might
be the “gene-flow”transfer of genes
from crops to weedy
relatives by crosspollination
Stem Cell History
1998 - Researchers first extract stem cells from human
embryos
1999 - First Successful human transplant of insulin-making
cells from cadavers
2001 - President Bush restricts federal funding for embryonic
stem-cell research