2. 2
DNA Extraction
What DNA source did you use?
Green peas.
Step 1: Why do we need to blend up our peas?
The peas are blend to break the cells open in order to release the DNA.
Step Observation Description
Adding 1/8 spoonful of salt to
200 ml cup of cold water
No observation Salt dissolves
½ cup of peas is put in the
blender and the salt water is
added. The peas are blended
for 15 seconds.
Thin green pea soup. The peas are blend to break
the cells open in order to
release the DNA.
The pea-soup is put in
another container and 1/6 of
liquid detergent is added
Thin green pea soup The detergent breaks down
the lipids in the cell
membrane and nuclei.
The mixture sits for 5-10
minutes and the enzyme
(meat tenderizer) is added.
Thin green pea soup. meat tenderizer breaks down
the proteins. The meat
tenderizer cuts away the
proteins.
Rubbing alcohol is added to
the mixture slowly and then
stirred.
Stringy, white precipitate
forms.
Alcohol is added so as to
make it easier to observe the
white wisps of DNA
3. 3
Observations
Thin green pea-cell soup.
Step 2: Explain in your own words why you added the detergent.
The detergent is added in order to break down the lipids in the cell membrane and the nuclei.
Observations
Thin green pea-cell soup.
Step 3: What is the purpose of adding enzyme? How does this help us isolate our DNA?
The enzyme is added to break down the proteins.
The enzyme (meat tenderizer) cuts the proteins away from the DNA.
Observations
Thin green pea-cell soup.
Step 4: Why did you add alcohol?
Alcohol is added so as to make it easier to observe the white wisps of DNA. Alcohol attracts
DNA more than water does. The DNA leaves the water and enters the alcohol when the alcohol
is placed on top. Only the DNA travels because all the other debris is more drawn to water than
to alcohol. Therefore, all that is left in your alcohol solution is DNA.
Observation
Stringy, white precipitate