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PHIL 341: Contemporary Moral Issues, Fall 2006


GE_Intro



November 20, 2006



Page



1




I.

Some of

the Techniques

of Biotechnology

(Adapted f
rom
Biotechnology and Food
, by Tom
Zinnen and Jane Voichick):



Selective breeding: Choosing desirable individuals or populations as breeding stock



Fermentation: Using microorganisms to convert a substance

such as starch or sugar into
other compounds such as carbon dioxide and ethanol



Genetic engineering: (Roughly) Transferring a copy of a DNA segment from one organisms
and inserting it into the DNA of another organism



Cloning: Making a genetic copy of a ce
ll or individual


II.

Biotechnology Timeline

Ancient biotechnology: selective breeding and fermentation



Circa 8000 B.
C.: early agrarian societies used selective breeding of both plants and animals



Circa 5000 B.
C.: Egyptians began making beer



Circa 4000 B.C.: E
gyptians used yeasts to bake leavened bread and make wine; Chinese were
using lactic
-
acid producing bacteria for making yogurt



Circa 2500 B.C.: Started collecting and storing seeds (germplasm) for future use

Traditional biotechnology: improvements in ferme
ntation from ancient to modern times



1700s: Brewers began producing alcohol in large quantities, developed top fermentation and
bottom fermentation, and improved the quality of the starter yeast



WWI: Glycerol, acetone, and butanol used for explosives



WWII:

Penicillin is developed



1950s: converted cholesterol into other steroids, such as cortisone, estrogen, and progesterone



1955: Used fermentation to produce amino acids, enzymes, and vitamins

Modern biotechnology: genetic engineering

and cloning



1953: Build
ing on Rosalind Franklin’s x
-
ray photographs of DNA, Francis Crick and James
Watson publish that DNA has a double
-
helix structure.



1971: Paul Berg and Herb Moyer produce the first recombinant DNA molecules



1971: At the Cold Spring Harbor laboratory Meeting
, molecular biologist Janet Mertz proposed to
introduce tumor
-
inducing DNA into E. Coli.



1973: The First Asilomar Conference was held to address biohazards working with
genetic
engineering involving
animal viruses



1974: Scientists adopt a temporary, volunt
ary moratorium on certain kinds of genetic engineering
research until the National Institutes of Health can establish guidelines.



1975: NIH publishes their guidelines



1980s: Researchers figured out how to use agrobacterium to transfer genes of interest int
o plants



1982: Eli Lilly used genetically engineered E. coli bacteria to produce human insulin



1990: Pfizer introduced the first genetically engineered product in the U. S. food supply, CHY
-
MAX chymosin, an enzyme used in cheese
-
making instead of rennet, w
hich digests the casein in
the milk and causes it to coagulate



1994: Calgene introduced the first genetically engineered whole food in the U. S. food supply, the
FLAVR SAVR tomato



1994: Posilac, Monsanto’s rBGH/BST product, goes on sale.



1994: FDA approves

Monsanto’s Roundup Ready soybeans, which are glyphosate tolerant



1995: EPA approved the use of Bacillus thuringiensis (Bt) producing potatoes



1996: Monsanto’s Roundup Ready soybeans are introduced to the US market



1996: Monsanto’s Bt corn is introduced t
o the US market.



1997: Scottish researchers
announce Dolly, a clone of an adult sheep.



1998: Researche
rs at the University of Wisconsin
-
Madison, led by James Thomson, establish 5
independent human embryonic stem cells lines.



2001: Schatten et al. at the Or
egon Regional Primate Research Center create the first transgenic
primate, ANDi, a rhesus monkey with a jellyfish gene for bioluminescence inserted into his
germline

PHIL 341: Contemporary Moral Issues, Fall 2006


GE_Intro



November 20, 2006



Page



2






2001: Barritt et al. at the Institute for Reproductive Medicine and Science of Saint Barna
bas,
reported “the first case of human germline genetic modification” achieved by transferring ooplasm
which contains mitochondrial DNA.



2001: Scientists at Advanced Cell Technologies (ACT) announced that they had successfully
made three cloned human embry
os to use for research; the scientific community concluded that
because the cloned embryos stopped dividing, the experiment was really a failure



2003: Jamie Thomson and Thomas Swaka announce the successful application of homologous
recombination

(a form of

genetic engineering that lets you target specific locations on the
genome)

in human embryonic stem cells.


III.

How to Genetically Engineer an Organism

Plants and animals are made up of cells, which contain nuclei
that

control the
cell’s functions
. Within

the
nuclei are chromosomes
,

long strands of DNA. DNA is a nucleic acid composed of two backbones made
of sugar and phosphate, and a linear
sequence

of bases on each backbone. The backbones are twisted
in a double
-
helix shape. The bases (represented by the

letters A (adenine
, pronounced “add
-
a
-
neen”
), C
(cytosine
, “sight
-
a
-
zeen”
), G (guanine
, “gwa
-
neen”
), and T (thymine
, “thigh
-
meen”)
) pair off with each
other (A with T and C with G), and those base pairs encode information in three letter words (codons).


This information is used (pp. 16
-
19), along with RNA, another kind of nucleic acid, but with a different
backbone and one different base (U (uracil
, “your
-
a
-
sill”
) instead of T (thymine)), to make proteins (a
string of amino acids, a kind of organic molecu
le). Each codon is an instruction which tells the cell to
make a certain amino acid. The DNA molecule is unzipped, and an mRNA (messenger RNA) molecule is
constructed which is complementary to the portion of DNA being utilized. This process in which DNA
ma
kes mRNA is called transcription.


Parts of the newly constructed mRNA are then excised (the removed parts are called introns, the
remaining parts are called exons), and the remaining mRNA is then transported out of the nucleus, into
the cytoplasm, and to
the ribosomes. Transfer RNA then transfers amino acids to the ribosome, which are
then arranged according to the mRNA to construct polypeptide chains (roughly, a protein or a part of a
protein). This process in which mRNA makes a polypeptide chain is calle
d translation. A segment of DNA
which encodes for a polypeptide chain is called a gene.


Genes thus carry genetic information
that

determine
s

how the cell will develop. Even though the DNA in
all the cells of an organism is the same, which segment gets use
d depends upon

the cells history and its
surrounding environment.
Thus, muscle cells behave differently than hair cells, even though they have the
same DNA.

The Key Steps of genetic engineering:

1.

Identify the gene that makes the protein you are intereste
d in.

2.

Transfer this gene from the species in which it occurs naturally to the species in which you want
the gene to be. (This typically takes a very large number of attempted transfers. Frequently, the
DNA isn’t taken up in the target cells or is taken
up but is not functional, or is taken up and
causes damage to the DNA resulting in the death of the target cell.)

Vectorless methods of transfer (pp. 35
-
36):

Biolistic delivery: DNA is mixed with tiny metal particles and fired into the target cells. Genera
lly speaking,
this method has a low uptake rate for the foreign DNA (not all particles go into the nucleus) and
sometimes causes damage.

Microinjection: Commonly used in animals (the cell wall of plant cells makes it difficult in plants) and has a
high rat
e of uptake.

Electroporation: Commonly used with plants cells and, to a lesser extent, fungal cells. The target cells are
placed in a solution of foreign DNA, and a strong electric field is applied. This opens up the pores
of the cell membrane and leads to

the DNA being taken up by the cells.

Shaking: Used with plant cells. Shake together a test tube containing water, the plant cells, the foreign
DNA, and tiny crystals of silicon carbide.

PHIL 341: Contemporary Moral Issues, Fall 2006


GE_Intro



November 20, 2006



Page



3




Transfer methods which use vectors (pp. 36
-
41)

1.

Obtain the desired
gene from the donor species (using restriction enzymes).

2.

Insert the gene into the vector species, using either a bacterium (pp. 37
-
38) or a retrovirus (pp.
28
-
29) with the capacity to inserts its DNA into the DNA of that which it infects. An adenovirus
can
also be used which inserts its DNA into the nucleus of the target cell, but the DNA doesn’t get
incorporated into the DNA of the cell. Thus, it doesn’t get passed on during cell division.

3.

Infect the target species with the vector species.