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DNA Technology
DNA Technology
• Different types of technology
can be applied to DNA based on
its structure to allow humans to
understand it better
• This means that through
technology we can use DNA to
our advantage to help solve
problems in the world around us
DNA Technology
• Some examples are
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Gel Electrophoresis
Cloning
PCR
Recombinant DNA Technology
Activation genes
• We will take a look at all of these
over the next few slides
Gel Electrophoresis
• Gel electrophoresis is a method
of sorting DNA based on size
• It is very useful to compare two
pieces of DNA to see if they are
similar
• DNA can be collected and run
through a sponge like gel
• The gel will separate the
segments of DNA by size
Gel Electrophoresis
• In order to get accurate
comparative result we have to
make sure that DNA cut
• By cutting DNA with restriction
enzymes we can cause DNA to
separate at specific base pair
combinations
• This causes different size
combinations from two similar
pieces of DNA
Gel Electrophoresis
Gel Electrophoresis
• We often use this to compare
two different samples of DNA
• We see if they are similar by
comparing how they travel
through the gel
• If two samples travel through
the gel in the same pattern, they
contain DNA of the same length
• This means that they have a
good chance of being related
Gel Electrophoresis
• Samples of DNA are placed at
the end of a segment of gel
• An electrical field attracts the
segments of the gel
• Smaller particles will travel
further
• Larger particles will travel
shorter
Virtual Demo
• http://learn.genetics.utah.edu/content/labs/gel/
Cell’s Potential
• Cells that are blank slates
are called stem cells
• Stem cells are cells that
have the potential to
become any other type of
cell
• A cell that already has
already developed and has
a purpose is called a
differentiated cell
• These cells have the same
set of DNA that is
contained in a stem cell
but are only using a
segment of it
Cell’s Potential
• A popular topic in science is how
to express the silent part of the
DNA in a differentiated cell
• How can we change the
differentiated cell into a new
type of cell?
• How can we get the DNA that
we want to be expressed
working?
Cell’s Potential
• A clone is an organism that is
produced asexually from a
single or group of cells
• Clones are organisms that can
be created from stem cells or
from differentiated types of
cells
• It all depends on what type of
organism you are trying to
clone
Cloning Plants
• Cloning plants is not as difficult as
you might think
• In fact several people in this room
might have cloned plants before
• If you have ever taken a “cutting”
from a plant to create an entire
new plant, you have cloned a
plant
• It is a way to asexually recreate a
new plant
Cloning Plants
• Cloning plants is now used
extensively in commercial
agriculture
• Plants that have desirable traits
are selected and they are asexually
reproduced
• Plants that produce more fruit, can
resist disease, grow quickly, etc
Cloning Plants
• This means that plants have the
ability to utilize sections of their
DNA that are normally not used
when they differentiate
• They can access different parts
of their DNA to create more
plant cells that can differentiate
Reproductive Cloning
• Animals do not have the same
ability to utilize DNA exactly like
a plant
• Most multicellular animals do
not have the ability to
regenerate like a plant
• However some animals can
regenerate lost body parts
Reproductive Cloning
• There are two main types of
cloning
• Reproductive cloning is the type
of cloning where a live organism
is born
• Therapeutic cloning has the
main goal of producing stem
cells for therapeutic treatments
Reproductive Cloning
• Most reproductive cloning of
complex animals is done
through the use of nuclear
transplantation
• Nuclear transplantation is the
process of removing a zygote’s
nucleus with a nucleus from a
somatic cell
• This would allow a cell to have
DNA from a donor cell and still
be able to divide
Reproductive Cloning
• Some organisms (mammals) need
to have that cloned cell eventually
implanted in a parental organism
• This will give them the chance to
develop
• These will eventually give rise to a
new organism
• However, that new organism will
be an individual
• The two cats seen here are clones
but have very different colors
Therapeutic Cloning
• Therapeutic cloning of animals can
involve trying to create more stem
cells from an organism
• Often times adult stem cells are
harvested to produce specific
tissues
• Adult stem cells are stem cells that
will only give rise to specific type of
cells
Therapeutic Cloning
• Adult stem cells from an animal
can be found in the skin, bone
marrow, hair, livers etc
• These cells are then then cloned
to create a new group of adult
differentiated cells
• These cells can then be used in
many different medical therapies
Introduction to PCR
• The amount of DNA that is
required for most of the tests,
experiments and labs is massive
• There are only a tests that can
be done on the DNA from a
single cell
• This is because there is a very
small amount of DNA that is can
be tested from a single piece of
DNA
Introduction to PCR
• Also in many scenarios, there
are limited supplies of DNA that
can be found, used or taken for a
test
• Tests done on fossilized
organisms, tests done at crime
scenes and tests done on foreign
samples might not contain
enough DNA to be conclusive
Introduction to PCR
• However there is a process to
create duplicate pieces of DNA
from a single piece of DNA
• The polymerase chain reaction
(PCR) is a method that is used to
create multiple copies of DNA
from a small starting amount
• It is a quick and simple process
that allows us to create enough
DNA to do accurate and viable
tests
PCR
• PCR was invented by the brilliant
but “troubled” scientist, Kary
Mullis
• His idea was to create a system
that would produce exact
replicas of DNA in a factory like
fashion
• This would allow researchers to
be able to manipulate large
amounts of DNA from a small
sample
PCR
• The process of PCR starts out in
a PCR vial
• It contains the original sample of
DNA, spare nucleotides (A,T,G
and C), DNA polymerase and
primers
• The sample is then heated to
90OC to 95OC for thirty seconds
• This seperates the hydrogen
bonds in the DNA
PCR
• The sample is then cooled down
to 55OC to 60OC and this allows
the primers to bind to the DNA
• This gives the DNA polymerase a
place to bind and start copying
DNA
• When the mixture is then
heated to 75OC for a full minute,
the DNA polymerase replicates
the remaining segments of DNA
PCR
• The whole process takes around
6 minutes
• The majority of the time is the
heating and cooling of the liquids
• This process can be repeated for
around three hours before there
is damage or fragmentation to
the original sample
• During this time you can go from
one single piece of DNA to
around one billion pieces of DNA
PCR
• This means that if one single
piece of DNA is found, you can
create a billion copies to test in a
very short period of time
• This allows for a small amount of
DNA to become enough to tell
us important things about an
organism
Video
• http://www.dnalc.org/resources
/3d/19-polymerase-chainreaction.html
• Simulation http://learn.genetics.utah.edu/c
ontent/labs/pcr/
On/Off Switch
• Think about the different types
of foods that you ate yesterday
• Where the macromolecules
different?
• Where the amounts and sources
different?
• This means the bacteria in your
gut have to be able to survive in
many different situations
On/Off Switch
• Gene regulation is the selective
turning on and off of genes
• This means that there are times
when DNA is expressed and
when it is not expressed
• Remember DNA  RNA 
Proteins
• The process from genotype to
phenotype is called gene
expression
lac Operon
• So lets think about E. coli
• E. coli is a bacteria that is
in your gut that is
required to breakdown a
disaccharide called
lactose
• Lactose is something
that is found in many
dairy products
• E. Coli breaks down
lactose with the enzyme
lactase
lac Operon
• Lactase takes a small time
amount of energy to produce
• So when there is dairy present
then lactase is produced
• However when dairy is not
present then E. Coli will not
waste energy producing lactase
lac Operon
• In order to control the
expression of the gene that
creates lactase there is an
operon
• An operator is a segment of DNA
that is between the promoter
and the DNA that codes for a
gene
lac Operon
• A group of genes that are related
and controlled are called a
operon
• Operons can be found almost
exclusively in prokaryotic
organisms
• They are grouped together in
the segment of prokaryotic DNA
so one on/off switch can control
the entire cluster
Operons
• When the gene is turned off there is a an active
repressor that attaches to the operator and blocks
RNA polymerase from binding
Operons
• When the operons are turned on the repressor is
inactivated (one of a few different ways) and mRNA is
able to be produced
Video
• http://www.youtube.com/watch
?v=oBwtxdI1zvk
X Inactivation
• That is how prokaryotes
activate and inactivate
genes
• Eukaryotes activate and
inactivate their genes
several different ways
• These different ways of
expression make life
varied for eukaryotic
organisms
X Inactivation
• The X chromosome is present in
males and females
• However female mammals do
not fully utilize their second X
chromosome
• This is so that females do not
produce more proteins as a male
of the same species
X Inactivation
• The active X chromosome is a
normal chromosome that
functions by undergoing protein
synthesis
• The inactive X chromosome
becomes a highly condensed
Barr body
X Inactivation
• Female embryonic cells will all
start out with two functioning X
chromosomes
• However early in the
development of the organism
one X is turned off at random
per cell
• The daughter cells from that cell
will have the same X inactivated
X Inactivation
• This means that as a female
mammal develops there will be a
mosaic of inactive X chromosomes
throughout her body
• This is seen in Tortoise Shell cats
• X chromosomes will carry the gene
for their color
• Based on what X chromosome is
turned on and which is turned off
determines their color