DNA Extraction From Plant Cells Practical Experiment

DNA is one of the genetic materials of

most living organisms including plants,

animals, bacteria, fungi and viruses it is

the hereditary material responsible for

  the passing on of characters of the

 parents to their offspring through

generations information is stored within the DNA molecule in the form of genes which are made up of several codons

     

formed by the four nitrogen bases

thymine adenine cytosine and guanine in

different combinations each codon is

made up of a combination of any three of

these four bases and are called triplet

codons these triplet codons are

transcribed into the complementary mRNA

which is then translated into the

corresponding amino acids encoded by the

triplet codons

these translated amino acids eventually

form proteins enzymes and other

biomolecules that drive the various

physiological functions within the

organism extraction and isolation of

this important molecule is the first

step in any experiment on genetic

engineering or recombinant DNA

technology

in biotechnology research extraction of

DNA is carried out using expensive

enzymes and chemicals under controlled

conditions in the lab setting

one can also extract and isolate DNA

using cheap and easily available

materials that one can find in any

household although it's a rudimentary

alternative to the method employed in

the laboratory the basic principle remains the same

the material is crushed to separate the

cells the cell wall and cell membrane of

the cell are then destroyed to reveal

the DNA which is then extracted into a

form that's visible to the naked eyes

in this video we'll try to extract and

isolate DNA from plant materials such as

leaves using materials that you can find

in your kitchen

to perform DNA extraction from plant

cells you will need the following

blender or pestle and mortar weighing

scale strainer or a funnel with filter

paper cone

250 ml beaker or cup

ice cold water

tablespoon or spatula

test tube or a small graduated cylinder

5 ml or 10 ml syringe or measuring pipet

glass rot or plastic straw

sodium chloride detergent powder or

liquid soap or Sds

meat tenderizing powder or ice cold

freshly prepared pineapple juice or

papaya juice

ice called ethanol or isopropanol

to begin the experiment weigh 50-100

grams of the plant material transfer it

into a pestle and mortar or blender and

blend it with about 100 ml of ice cold

water and half a teaspoon of common salt

the reason we add sodium chloride is

because it has two important functions

to perform

sodium chloride helps to remove proteins

that are found within the cell and also

bound to the DNA it also helps to keep

the proteins dissolved in the aqueous

layer so they don't precipitate in the

alcohol along with the DNA in the later

part of this experiment the sodium ions

create a temporary attraction between

the positively charged sodium and the

negatively charged phosphate backbone of

the DNA thus neutralizing the DNA

this makes DNA less hydrophilic and can

easily be dissociated or precipitated

from the water

filter the blended mixture into a beaker

using a strainer or a funnel with a

filter paper cone

add a tablespoon of detergent powder

dishwashing liquid soap or Sds to the

filtrate in the beaker and stir the

mixture gently

allow the mixture to stand for 5 to 10

minutes

during this time the detergent starts to

dissolve the cell membrane of the plant

cells which is a lipid bilayer and also

the cell wall the detergent molecules

interact with the lipid particles in the

cell membrane and removes them thus

exposing the DNA or genetic material of

the plant cells after 10 minutes or so

transfer about 10 ml of the mixture in

the beaker in a test tube or a graduated

cylinder add a pinch of meat tenderizing

powder or about 5 ml of pineapple juice

or papaya juice to it gently agitate the

test tube to mix the two liquids wait

for 5-10 minutes for the digestion

reaction to occur

meat tenderizer contains papain enzyme

pineapple contains bromelain enzyme

these are protease enzymes and are able

to break down proteins bound to the DNA

now hold the test tube in an inclined

position and using a glass rod or

pipette carefully add about five ml of

ice cold rubbing alcohol or ethanol such

that the alcohol flows gently down the

inner wall of the test tube and forms a

layer on top of the digested plant

extract in the tube

observe the interface between the two

liquids you will find that the DNA begin

to precipitate in the alcohol in the

form of white

gelatinous strings or clumps

alcohol such as ethanol and isopropanol

are non-polar solvents addition of

alcohol to the sodium-bound DNA forces

the DNA and sodium ions to become even

more tightly bonded since alcohol is

very non-polar

this tight binding between DNA and

sodium makes it even more hydrophobic

and eventually the DNA dissociates or

precipitates out from the water layer

and into the non-polar alcohol layer in

the form of a white cloudy precipitate

at the water alcohol junction you can

separate and remove the DNA thus

obtained by spooling it onto a plastic

straw or a wooden stick

this is all about extracting DNA from

plant cells that you can perform at home

thanks for watching you

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