A Simply Fruity DNA Extraction: Category: Type: Rough Parts List
A Simply Fruity DNA Extraction: Category: Type: Rough Parts List
A Simply Fruity DNA Extraction: Category: Type: Rough Parts List
To break open the cells of the strawberry we need a lysis buffer. Prepare the lysis buffer in a cup as follows: mix 100ml of water, 100ml of soap, and 1 tablespoon of salt.
Remove the leaves from the strawberry, place the berry in the freezer bag and mash it up really well using your hands.
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Add lysis buffer to the bag, close and squish for a few minutes. Mix carefully, the fewer bubbles created the better the results.
Cover the plastic cup with the cheese cloth and push the strawberry/detergent mix through the muslin little by little. Throw away the cloth.
Pour the alcohol into the cup and wait 1-2 minutes for the DNA to start precipitating out. You should see a white fluffy cloud form, this is the DNA.
View of the precipitated DNA from above. Use the toothpick to lift the DNA out of the alcohol. Voila! Strawberry DNA.
Fine
Points:
The
lysis
buffer
can
be
made
in
class
by
the
students
or
made
beforehand
by
the
teacher.
For
the
soap
you
can
use
dish
liquid,
hand
soap
or
shampoo.
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Mission
Science
Workshop.
All
Rights
Reserved
worldwide.
When
linking
to
or
using
MSW
content,
images,
or
videos,
credit
MUST
be
included.
Dont use a sandwich bag as these are thinner than freezer bags and can break during strawberry mashing. Other fruits can be used but strawberries are easy to mash. They are also octoploid, which means that they contain a lot of DNA. You can isolate human DNA but you will need to get someone to fill a shot glass with spit! 100% isopropyl alcohol or 95% ethanol can also be used to precipitate DNA. The alcohol needs to be ice-cold so leave the bottle in the freezer overnight before the class. The precipitation normally begins immediately but the DNA can take a couple of minutes to condense.
Objectives:
During this experiment, students will: 1. Extract DNA from a Strawberry and understand that DNA is in the food they eat. 2. Understand why each step of the experiment is peformed. 3. See DNA with their own eyes.
Concepts
Involved:
Deoxyribonucleic
acid
(DNA)
is
the
molecule
that
controls
everything
that
happens
in
the
cell.
It
contains
instructions
that
direct
the
activities
of
cells.
DNA
may
be
extracted
with
a
simple
method
using
household
items.
Each
step
is
necessary
because
of
the
complex
way
that
DNA
is
packaged
in
cells:
Soap
is
used
to
break
down
the
cell
membrane,
a
lipid
bilayer.
Salt
helps
to
remove
proteins
bound
to
the
DNA.
It
also
helps
to
keep
the
proteins
soluble
in
the
water
layer
(detergent)
and
stops
them
from
precipitating
with
the
DNA
into
the
alcohol.
The
alcohol
causes
the
DNA
to
precipitate
i.e.
to
separate
in
solid
form
from
a
solution.
Focus Questions:
1. Why would we want to extract DNA from things? 2. Can you think of something youve seen before that looks like the DNA? 3. Compare the DNA youve extracted to the size of the strawberry originally. How much of the strawberry was DNA? 10%? 1%? Less than 1%? How could you figure that out for sure?
Elaboration:
All
organisms
are
made
up
of
cells,
from
simple
single-cell
bacteria
to
multi-cell
humans
and
plants.
It
doesnt
matter
if
you
are
human,
a
bacteria
or
a
strawberry,
every
cell
contains
deoxyribonucleic
acid
(DNA).
DNA
is
the
blueprint
that
determines
everything
that
happens
in
a
cell.
It
contains
instructions
that
are
used
in
its
development,
function
and
reproduction.
Removing
DNA
from
a
cell
is
called
DNA
extraction.
Extraction
of
DNA
from
cells
and
its
purification
are
techniques
that
are
very
important
to
scientists.
Isolating
DNA
allows
scientists
to
identify
and
study
genetic
diseases,
and
if
they
experiment
further
with
this
DNA
they
can
discover
new
treatments/medicines.
Scientists
can
also
genetically
engineer
organisms
in
the
lab
to
produce
things
that
are
beneficial
to
humans,
such
as
insulin.
In
forensic
science
DNA
is
used
to
answer
questions
such
as
maternity/paternity,
or
whether
a
person
was
present
at
a
crime
scene.
These
tests
take
advantage
of
the
fact
that
every
person
on
the
planet
has
a
unique
DNA.
In
this
experiment
we
make
our
own
DNA
extraction
kit
from
household
materials
and
use
it
to
purify
DNA
from
strawberries.
We
are
using
strawberries
to
extract
DNA
because
their
cells
each
have
eight
copies
of
the
genome
in
every
cell.
This
means
that
it
has
a
lot
more
DNA
per
cell
than
an
organism
that
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Mission
Science
Workshop.
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Rights
Reserved
worldwide.
When
linking
to
or
using
MSW
content,
images,
or
videos,
credit
MUST
be
included.
only has one or two copies. It also means that we have a better chance at having a successful DNA preparation! During the DNA extraction, we use physical force (mashing the strawberry) and the lysis buffer to break open the cell and release the DNA into solution. DNA is highly soluble in water because the phosphate group of each nucleotide carries a negative charge. Positively charged sodium ions from the salt in the lysis buffer are attracted to the phosphate groups on the DNA. This neutralizes DNA's electric charge, and allows the DNA to clump together. The DNA precipitates out in the presence of the alcohol because it is not soluble in alcohol. How can we be sure that we have isolated DNA? This class can be extended using experiments to confirm that we have DNA. Place a drop of distilled water on a microscope slide. Use a toothpick to remove a tiny piece of the DNA from the toothpick. Put a coverslip over the DNA and add a drop of methylene blue at the edge of the cover slip and use the corner of some paper towel to draw the stain under. Look at the DNA under the microscope and write down what you see. It should be noted that the white stringy stuff that we see is a mixture of DNA and RNA, and that the protocol that we have used is a nucleic acid isolation. Using other chemicals in a proper lab setting, a very very pure sample of DNA could be isolated.
Grades
k-8
Standard
Set
Investigation
and
Experimentation:
Scientific
progress
is
made
by
asking
meaningful
questions
and
conducting
careful
investigations.
As
a
basis
for
understanding
this
concept
and
addressing
the
content
in
the
other
strands,
students
should
develop
their
own
questions
and
perform
investigations.
Grades
k-12
Mathematical
Reasoning:
1.0
Students
make
decisions
about
how
to
approach
problems:
1.1 Analyze
problems
by
identifying
relationships,
distinguishing
relevant
from
irrelevant
information,
sequencing
and
prioritizing
information,
and
observing
patterns.
1.2 Determine
when
and
how
to
break
a
problem
into
simpler
parts.
2.0
Students
use
strategies,
skills,
and
concepts
in
finding
solutions:
1.1 Use
estimation
to
verify
the
reasonableness
of
calculated
results.
1.2 2.2
Apply
strategies
and
results
from
simpler
problems
to
more
complex
problems.
1.3 Use
a
variety
of
methods,
such
as
words,
numbers,
symbols,
charts,
graphs,
tables,
diagrams,
and
models,
to
explain
mathematical
reasoning.
2.5
Indicate
the
relative
advantages
of
exact
and
approximate
solutions
to
problems
and
give
answers
to
a
specified
degree
of
accuracy.
3.0
Students
move
beyond
a
particular
problem
by
generalizing
to
other
situations:
3.1
Evaluate
the
reasonableness
of
the
solution
in
the
context
of
the
original
situation.
3.2
Note
the
method
of
deriving
the
solution
and
demonstrate
a
conceptual
understanding
of
the
derivation
by
solving
similar
problems.
3.3
Develop
generalizations
of
the
results
obtained
and
apply
them
in
other
circumstances.
Grade
7
Standard
Set
1.
Cell
Biology.
All
living
organisms
are
composed
of
cells,
from
just
one
to
many
trillions,
whose
details
usually
are
visible
only
through
a
microscope.
As
a
basis
for
understanding
this
concept:
7.a.
Students
know
cells
function
similarly
in
all
living
organisms.
7.b.
Students
know
the
characteristics
that
distinguish
plant
cells
from
animal
cells,
including
2012
Mission
Science
Workshop.
All
Rights
Reserved
worldwide.
When
linking
to
or
using
MSW
content,
images,
or
videos,
credit
MUST
be
included.
chloroplasts and cell walls. 7.c. Students know the nucleus is the repository for genetic information in plant and animal cells. Grade 7 Standard Set 2. Genetics. A typical cell of any organism contains genetic instructions that specify its traits. Those traits may be modified by environmental influences. As a basis for understanding this concept: 2.d. Students know plant and animal cells contain many thousands of different genes and typically have two copies of every gene. The two copies (or alleles) of the gene may or may not be identical, and one may be dominant in determining the phenotype while the other is recessive. 2.e. Students know DNA (deoxyribonucleic acid) is the genetic material of living organisms and is located in the chromosomes of each cell. Grade 8 Standard Set 6. Chemistry of Living Things (Life Sciences) Principles of chemistry underlie the functioning of biological systems. As a basis for understanding this concept: 8. c. Students know that living organisms have many different kinds of molecules, including small ones, such as water and salt, and very large ones, such as carbohydrates, fats, proteins, and DNA.
2012 Mission Science Workshop. All Rights Reserved worldwide. When linking to or using MSW content, images, or videos, credit MUST be included.