DNA EXTRACTION

Detergent

eNzymes

Alcohol

Purpose of

DNA

extraction…

Isolation of DNA is often the first

step before:

• DNA profiling

• cloning

• disease diagnosis

• DNA sequencing

• genetically modified organisms (GMO) -

agriculture, pharmaceutical

• Environmental testing, bioterrorism

… so it is an

important lab

skill to learn.

Summarize this purpose in your

lab book.

Laboratory

Protocol

Create a table like this in which you fill in the steps of the procedure and the biological explanation behind what is occurring at each step:

Protocol Directions Explanation

1.

2.

Laboratory

Protocol

1. Obtain the cup containing 10 ml Gatorade from

your instructor.

2. Take the Gatorade from the cup into your mouth,

and swish the water around vigorously for 60

seconds. Gently chew the insides of your

cheeks. It is NOT helpful to drawblood!

3. Carefully expel the liquid into the plastic vial.

4. Dispose of the paper cup in the trash.

Cell

Collection

Gently chewing the

inside of the mouth

combined with a water

mouth wash is used to

dislodge epithelial cells

lining the mouth

Ample cell collection is

critical for success.

Why

Gatorade?

Na+

Na+

Na+

Na+

O CH2

O

P O

O

O Base

CH2

O

P

O

O

O

Base

OH

Sugar

Sugar

O

• Gatorade contains salt

• Na+ ions of NaCI

bind to the phosphate groups of DNA molecules, neutralizing the electric charge of the DNA molecules.

• The addition of

NaCI allows the DNA molecules to come together instead of repelling each other.

Laboratory

Protocol

5. Obtain the detergent from your workstation, and

add 2 ml of detergent to your plastic vial.

6. Place the cap on the vial and gently invert your

tube 5 times (don’t shake it!).

7. Let your vial sit

undisturbed for 10 minutes.

Why Detergent?

To break open the cell and nuclear membranes, allowing

the DNA to be released into the solution

Laboratory

Protocol

8. Add a pinch of meat tenderizer to your vial.

9. Place the cap on your vial

and gently invert it a few

times.

10. Let sit for 10 minutes.

Why Add

Meat

Tenderizer?

• Meat tenderizer is made of enzymes that

break down proteins in meat.

• In this case, the enzymes destroy

proteins that bind DNA.

• This treatment increases the amount of

intact DNA that is extracted.

Laboratory

Protocol

11.Gently pour COLD ethanol into your vial so that

it forms a layer on top of the Gatorade solution

12.Let sit for 10 minutes.

Adding Ice

Cold

Alcohol?

• DNA does not dissolve in alcohol.

• The addition of cold alcohol makes the DNA

clump together and precipitate out of

solution.

• Precipitated DNA molecules appear as long

pieces of fluffy, stringy, web-like strands.

• Microscopic oxygen bubbles “aggregate” ,

or “fuse” together, as the DNA precipitates.

• The larger, visible air bubbles “lift” the DNA

out of solution.

Post Lab

Questions

ANSWER IN COMPLETE SENTENCES

1. DNA is a microscopic molecule. How

come we can see it?

2. List five potential applications of DNA

extraction.