DNA extraction is a method used to purify DNA from a sample by separating it from other cellular components using physical and chemical techniques. It involves lysing cells and solubilizing the DNA using detergents and enzymes. Common extraction methods include organic extraction, non-organic extraction, and adsorption. DNA can then be extracted from various samples for purposes like genetic testing, forensic analysis, and body identification.

1. DNA EXTRACTION
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2. Genetic
testing
Body
identification
Analysis of
a forensic
evidence
DNA Extraction
• DNA extraction is a method use to purify DNA by using physical and/or chemical methods from a sample
separating DNA from cell membranes, proteins, and other cellular components.
• It involves lysing the cells and solubilizing DNA, which is followed by chemical or enzymatic methods to
remove macromolecules, lipids, RNA, or proteins.
DNA extraction techniques include organic extraction (phenol–chloroform method), nonorganic
method (salting out and proteinase K treatment), and adsorption method (silica–gel membrane).

3. The basic criteria that any method of DNA isolation from any sample
type should meet include:
(1) efficient extraction of DNA from the sample
(2) production of a sufficient amount of DNA for use in downstream
processes
(3) successful removal of contaminants
(4) isolation of high quality and high purity DNA.
Samples used for DNA extraction can be taken from human tissues,
blood, hair, rodent tissues, leaf tissue, bacteria, yeast, fungi, insect, stool, body
fluids, spores, soil, clinical samples (e.g., biopsy samples, fine needle aspirates),
forensic samples (e.g., dried blood spots, buccal swabs), and fingerprints.
INTRO

4. Collection of sample
Cell lysis
Precipitation of DNA
Removal of the DNA
FLOW CHART OF THE DNA EXTRACTION
Source: Retrieved November 22, 2022 from
https://learn.genetics.utah.edu/content/labs/extraction
LYSIS
SOLUTION
ISOPROPYL
SALT
SOLUTION

5. This composes of two chemicals:
a. Detergent - disrupts the cell membrane and nuclear
envelope.
b. Proteinase K - Hydrolyzes histones apart freeing DNA. It
inactivate DNases and RNases that would otherwise degrade
a desired DNA or RNA sample.
LYSIS SOLUTION
DNA’s sugar phosphate backbone is charged. By adding salt,
it helps neutralize the DNA charge and make the molecule
less hydrophilic, meaning it becomes less soluble in water.
The salt also helps to remove proteins that are bound to the
DNA and to keep the proteins dissolved in the water.
SALT SOLUTION
Figure 1:
Figure 2:

6. It performs three (3) different functions in DNA extraction, which are precipitation
washing and storing.
It is because DNA is not soluble in alcohol, it allows the sodium ions to interact
with the DNA molecules more easily. Wherein, the colder the alcohol, the less soluble DNA
will be in it.
ISOPROPYL SOLUTION
Polar and nonpolar molecules dissolve in polar and
nonpolar solutions, respectively. Solute and solvents dissolve
properly only if they have a similar structure. DNA is a polar
molecule and soluble in water as water is also partially polar.
But water can destroy everything, the positive
charge of water will try to dissolve and stabilize it. So what
happens is that in the addition of alcohol, the net negative
charge of alcohol makes the positive charge of water busy.
This disallows water to interact with the DNA,
meaning, that alcohol prevents the Na and PO3– complex by
neutralizing other positive charges. With the addition of more
and more alcohol it neutralizes as many positive charges as
possible from the solution and precipitates DNA in a visible
form.

7. What is the purpose of the warm water bath in
DNA extraction?
The warm water bath helps the DNA to be freed from the cells. The warm water will melt the membranes and then afterwards
eethe soap can be added to dissolve the lipid layers.
Why does the DNA sink to the bottom of the tube
after it is being centrifuged?
The centrifuge aids in separating the DNA and its impurities based on their difference in molecular weight. Wherein, the
molecular weight of DNA is lighter than the other cell material, like proteins and cell walls. So, by spinning the sample with
centrifuge, the material from the DNA can be separated thus a cleaner DNA sample.
What does the centrifuge do in the process? Why
does it needs to be balanced?
The water is “pushed” against the bottom of the bucket by what is colloquially known as “centrifugal force.”
Though not a real force, but a reaction to the centripetal force, centrifugal force pushes against the bottom of the bucket.
This causes the particles in the solution to clump at the bottom of the tube. That solid clump is called a pellet, and the
solution above it is called the “supernatant”.

8. 1. The molecules will travel through the gel in different directions or at different speeds based on what?
2. This is known as the filter that sorts the DNA strands which usually looks like a sponge that is made of a Jell – O.
3. What is the chemical name of Ethidium bromide?
4. Which DNA strands will move the farthest? that move the nearest?
5. This is the isolation of any sub – cell structures.
6. What are the three (3) processes involved in cell fractionation?
7. How long usually for the DNA to run in a gel electrophoresis?
8. What do the presence of ‘bubbles’ mean?
9. Based on your simulation at the website in ‘genetics Utah’, the period of how long should the gel electrophoresis runs
depends on what factors?
10.What is the purpose of the salt water solution?
11.What is the difference between fractionation and centrifugation?
12. Ethidium bromide is used as a what?
13. What is the relationship of the length of molecules and their speeds?
14. Gel electrophoresis separates DNA fragments based on their size and charge. In the process, the molecules or the DNA
strands is pushed through a gel that contains the small pores. What pushes the DNA strands into the small pores of the
gel?
GEL ELECTROPHORESIS

9. It is a technique used to separate DNA
fragments based on their sized and charge.
A filter that sorts the DNA strands and is like
a sponge made of a Jell – O with many small
holes in it.
GEL ELECTROPHORESIS
GEL
Electrophoresis
Refers to a technique that uses electrical
current to separate DNA, RNA or proteins
based on their physical properties such as
size and charge.

10. Principle of Gel Electrophoresis

11. WHAT IS USED?
a. Agarose gel
A component of agar. It forms a 3D gel matrix of helical agarose
molecules in supercoiled bundles held by hydrogen bonds, with
channels and pores through which molecules are able to pass.
When heated, these hydrogen bonds break, turning the agarose
to liquid and allowing it to be poured into a mold before it resets.

12. • Percentage of agarose included in a gel impacts the pore sizes and thus the size of
molecules that may pass through and speed at which they do so. The higher the
percentage of agarose, the smaller the pore size, thus the smaller the molecules able to
pass and the slower the migration.
• 0.7-1% agarose gel is typically used for day-to-day DNA separations, offering good, clear
differentiation of fragments in the range of 0.2-10 kb. Larger fragments may be resolved
using lower percentage gels, but they become very fragile and hard to handle, while
higher percentage gels will give better resolution of small fragments but are brittle and
may set unevenly.

13. b. Ethidium bromide
This is an intercalating dye and is incorporated in the gel during setting. This binds the
DNA and fluoresces under UV light, allowing the DNA fragments to be visualized. The
more DNA present, the brighter the band.
Key steps in Gel
Electrophoresis:
• Determine the required gel percentage
• Pour a gel
• Mix samples/ ladders with loading dye
• Load the gel
• Run the gel
• Visualization

14. HOW TO READ GEL
ELECTROPHORESIS
Base pairs are two complementary DNA
nucleotide bases that pair together to form a
“rung of the DNA ladder.”
In humans it ranges in size from about 50
million to 300 million base pairs. Although in 23
chromosomes, it only consists of approximately
3 billion base pairs of DNA.

15. Agarose gel (2%) analysis of PCR-amplified products
from DNA extracted from a bronchoalveolar lavage
(BAL) diagnostic specimen of a patient with pulmonary
symptoms. Credit: The Centers for Disease Control and
Prevention.

16. In the well, DNA is a negatively charged molecule due to the phosphate
groups that constitute the backbone of DNA, which is due to the presence
of bonds created between the phosphorus and oxygen atoms. Therefore,
by placing the DNA at the negative end of the gel matrix, when the current
is turned on the DNA will migrate down the gel towards the positive side
because the opposite charges attract.

17. IMPORTANCE OF GEL ELECTROPHORESIS
• Visualization of sample DNA
a. Whether DNA is present in a sample.
b. The sizes of DNA fragments present.
c. How clean the sample is.
• Separation of DNA fragments for purification
• Separation of DNA fragments for Southern blotting
• Electrophoretic mobility shift assays (EMSAs)

18. THANKS