Ch14: Biotechnology and Society

lessfrustratedBiotechnology

Oct 23, 2013 (4 years and 2 months ago)

95 views

Ch14: Biotechnology and Society

Biotechnology


The use of recombinant DNA and molecular
biology to produce commodities or services.



Changed the way that we produce our food,
diagnose and treat diseases, trace our ancestry,
gather evidence in criminal cases, identify human
remains, and protect endangered species.

Recombinant DNA


Joining together DNA from two or more
sources


Scientists can investigate the structure
and function of genes


Recombinant DNA process


DNA being used is joined to a plasmid.


DNA is cut using restriction enzymes


Creates sticky ends that will bond to another DNA molecule
with a complementary sequence.


A plasmid is circular piece of DNA found in bacteria
and yeast. (contains a signal for replication)


Contains a genetic marker, so scientists can distinguish
if the bacteria carries the human gene.

Why is this useful?


Mass produce many important human
proteins…insulin, HGH, blood
-
clotting
proteins.


Biopharming


Genetic Engineering with crops


Transgenic animals used as models for
human diseases


DNA fingerprinting


Ethics

Biopharming


Insulin


Used to be extracted from cow and pig organs


1982, using recombinant DNA technology, created
synthetic insulin.


Blood
-
clotting proteins


1960’s, used donated blood to collect clotting proteins.


60% of all hemophiliacs became infected with HIV.


Started using recombinant DNA technology in the
90’s…haven’t had any new cases since.


Human proteins made in animals.


Pompe

disease


Buildup of glycogen, causes loss of heart and muscle
function.


Receive enzyme replacement therapy.


Uses hamster cells to make mass batches of the
protein.

Biopharming


Humans have been genetically modifying crops
for better yield for thousands of years…artificial
selection.


Transgenic plants receive one or a few genes as
opposed to thousands via artificial selection


Resistance to insects and/or herbicides


Genes can originate from plants, animals, fungi or
bacteria

Genetically Modified Foods

Resistance to

herbicides and disease


Herbicide resistance crops


Contain genes for resistance to herbicides


Crops can be sprayed and it will not kill the crop


Herbicide is broken down in the soil relatively quickly.


Corn, cotton and soybeans resistant to insects


Carry a bacterial gene that releases toxins in the
insect’s gut.

Genetically Modified Plants


At least 60
-
70% of the processed foods in the
supermarket contain at least a small amount of
one or more of the transgenic plants approved
for commercial production in the United States.


Corn, soybeans, cottonseed, and canola oils


Will increase as nutritionally enhanced grains are
approved.

Increasing the nutritional value…


Fortified foods are already on the market


Vitamin D enriched milk


Flour enriched with Vitamin B


Crops can be modified to increase their
nutritional value


Diets deficient in Vitamin A can result in blindness


Huge problem in many countries


Golden Rice, free distribution in many countries

Transgenic functional foods


First modified foods benefitted the farmer,
now the goal is to benefit the consumer


Enhancing the nutritional value


Functional foods

(provide benefits above and
beyond nutritional value)


Increased omega fatty acids (brain/eye development
and prevention of cardiovascular disease)


Increased levels of antioxidants and minerals


Genetically
Engineered Foods


U.S. approval for GM
foods:


Corn


Soy


Papaya


Canola


Potato


Rice


Tomatoes

Opposing Views


Creation of super pests


Creation of super weeds


Loss of biodiversity


Biotechnology companies control
agriculture


Health concerns

Labeling Concerns


In 1992, the Food and Drug Administration claimed
they had no information showing that GM foods
were substantially different from conventionally
grown foods. Therefore they are safe to eat, and
absolutely no safety studies were required.


The U.S. Food and Drug Administration currently
requires labeling of GE foods if the food has a
significantly different nutritional property.

Ex: peanut protein in a soybean product


Early in 2001, the FDA proposed voluntary guidelines
for labeling food that does or does not contain GE
ingredients

Transgenic Animals:

Models of Human Diseases


Scientists have found that many human genes can
be found in other organisms.


Transfer mutant human disease alleles into model
organism


Symptoms that mirror those in humans


Study early stages of development and disease
progression


Test medications to
treat symptoms

Cloning

Cloning


Clones


Molecules, cells, or
individuals derived from a
single ancestor


This does not genetically
modify the organism.

Cloning: Embryo Splitting


Embryo Splitting


Unfertilized egg is taken by a donor mother


Fertilized via
in vitro
fertilization (IVF)


Forms an embryo containing 4
-
8 cells


Cells are separated from each other, then they divide to
form genetically identical embryos.


Embryos implanted into surrogate mothers for
development

**Similar to nature’s way of producing identical
twins/triplets




Nuclear Transfer


Egg cell and the surrounding cells are removed from
the ovary


Cells are separated and the nuclei are removed from
each cell.


The cumulus cell’s nucleus (cells that were
surrounding egg cell) is now injected into the
enucleated egg cell.


Egg is implanted into surrogate mother.


Cloning:
Nuclear Transfer

Nuclear Transfer


Dolly the sheep (1997)


Nuclear transfer via cell
fusion (very similar to
the previous
description)


Showed that highly
specialized adult cells
can direct all stages of
development when
transferred into egg
cells.


Animal cloning has
great impact on
farming…why?

Gene Cloning/Copying


Recombinant DNA


Polymerase Chain Reaction (1980s)


Form of DNA replication


Two components: strands of DNA (template) and
Primers (regulate the start of replication)


Can amplify the original DNA sequence millions of
times over a few hours


PCR

1.
Solution of DNA is
heated to 90⁰ to 100
⁰C to break the H
bonds between
strands. These two
strands will now
serve as templates.

2.
Solution is rapidly
cooled to 50⁰C and
primers bind to
complementary
strands on the DNA
fragments. The
primers mark the
boundaries of the
region that needs to
be copied.

3.
Enzyme (
Taq

polymerase) synthesizes
a complementary strand
beginning at the
primers.

Steps 1
-
3 make up one PCR
cycle…these steps are
repeated each time and
each new strand is
replicated in each cycle.
This happens over a
matter of hours instead
of weeks.

PCR

Gel Electrophoresis


Used to provide genetic information in a wide
range of data fields.


Provide evidence in criminal cases


Diagnose genetic diseases


Solve paternity cases


Samples can be obtained from any DNA
-
containing tissue or body fluid (cheek cells,
blood, skin, and hair).

Other uses of Electrophoresis


Conservation biologists determine kinship
among populations/individuals


Captive breeding programs, zoos



Evolutionary biologists use DNA profiles to
compare similarities and differences among
species to construct hypothetical family trees.

Gel Electrophoresis


Gel electrophoresis is a technique used to
separate DNA fragments based on size, yielding a
unique “fingerprint.”



DNA is a
negatively

charged molecule, so it will
move to the positive end of the gel.


Fragments that are smallest in size are able to
travel the farthest from the well; whereas large
fragments travel only a short distance from the
well.


For this lab, we will look at Short Tandem
Repeats (STRs)


These are non
-
coding regions that contain
repeated segments.


Each person has a different number of repeats
for the two alleles that you have (one from
mom, one from dad)


DNA profiling is performed at many loci to
improve the Power of Discrimination


Making the Gel


After making the gel, place it in an
electrophoresis chamber and add buffer to
cover the gel.


Be sure the wells are placed at the negative
electrode end.
WHY?

Loading the Gel


Since we cannot see DNA
without special dyes, we
add a tracking dye to each
reaction tube.


This does not stain the
DNA, but because of their
size, the dye molecules
move at a rate that is
similar to that of the DNA.

Staining and Photographing the DNA


After electrophoresis, you must stain the DNA for
visualization.


Submerge the entire gel in
methylene

blue, which will
bind to the DNA.


Rinse the gel repeatedly with water, so that the dye
washes off the gel.



The DNA will appear as blue bands that are easily
seen when a light is passed through the gel.

Analysis of Results


Each fragment of DNA is a particular number
of nucleotides, or base pairs, long.


When researchers want to determine the size
of DNA fragments produced with particular
restriction enzymes, they run the unknown
DNA alongside DNA with known fragment
sizes.