Contemporary Moral Issues - Biotechnology

hollandmercifulBiotechnology

Dec 11, 2012 (4 years and 10 months ago)

205 views

PHIL 341: Contemporar
y Moral Issues, Fall 2005


GE_Intro



November 8, 2005



Page



1




I.

Some of

the Techniques

of Biotechnology

(From
Biotechnology and Food
, by Tom Zinnen and
Jane Voichick):



Selective breeding: Choosing desirable individuals or populations as breeding stock for new
generations



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


II.

Biotechnology Timeline

An
cient 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.: Egyptians 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: successive improvements in fermentation from ancient to modern t
imes



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: Building 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 Mert
z proposed to
introduce tumor
-
inducing DNA into E. Coli.



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



1974: Scientists adopt a temporary, voluntary moratorium on certain kinds of genetic engineering
researc
h 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 into plants



1982: Eli Lilly used genetically engineered E. coli b
acteria 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, which digests the casein in
the milk and causes it to coagulate



1993: the FDA approved Monsanto’s rBGH/BST



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



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 to the US market.



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



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



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



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

PHIL 341: Contemporar
y Moral Issues, Fall 2005


GE_Intro



November 8, 2005



Page



2





III.

How to Genetically Engineer an Organism

Plants and animals are made up of cells, which contain nuclei which control the functions of the cell.
Within the nuclei are chromosomes
, which are long strands of DNA. DNA is a nucleic acid composed of
two backbones made of sugar and phosphate, and a linear arrangement of bases on each backbone. The
backbones are twisted in a double
-
helix shape. The bases (represented by the letters A (ad
enine
,
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 informat
ion 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 molecule). Each cod
on 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
makes mRNA is c
alled 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 called translation
. A segment of DNA
which encodes for a polypeptide chain is called a gene.


Genes thus carry genetic information which determine how the cell will develop. Even though the DNA in
all the cells of an organism is the same, which segment gets used depends upo
n the surrounding
environment of the cell. 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 interested 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 functiona
l, 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. Generally speaking,
this meth
od 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 rate of uptake.

Electropor
ation: 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.

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

1.

Obtain the desired gene from the donor spe
cies (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.