Extracting DNA Lab

MS-LS3-1 - Develop and use a model to describe why structural changes to genes (mutations) located on chromosomes may affect proteins and may result in harmful, beneficial, or neutral effects to the structure and function of the organism.

Learning Target

Students begin to develop a conceptual model to explain how genetic information is passed on to other generations by the chromosomes in cells.

Success Criteria

I can demonstrate proper lab procedures including note taking and safety.
I can make the connection between what I know about cells and how that relates to the passing along of genetic traits.

Questions to Ponder

Where have you heard of DNA before?
What is DNA? What do the initials stand for?
How is DNA used to carry the genetic instructions for all organisms to live and grow?

What is DNA?

Deoxyribonucleic acid (DNA) is a molecule composed of two chains that coil around each other to form a double helix carrying the genetic instructions used in the growth, development, functioning, and reproduction of all known living organisms and many viruses.

Fruit DNA Extraction

Your goal is to extract the DNA out of a banana sample. Each banana is made of plant cells. Plant cells are different from our own cells. Notice the image that illustrates a plant cell. The DNA is located in the nucleus of the cell. The nucleus is a very small bubble made up of lipids (fats). The cell wall houses the organelles. The cell wall is hard and stable- alike a brick wall of a house. The cell walls are not made of lipids but instead made of cellulose.

The long, thick fibers of DNA store the information for the functioning of the chemistry of life. DNA is present in every cell of plants and animals. The DNA found in banana and banana cells can be extracted using common, everyday materials. We will use an extraction buffer containing salt, to break up protein chains that bind around the nucleic acids, and dish soap to dissolve the lipid (fat) part of the banana cell wall and nuclear membrane. This extraction buffer will help provide us access to the DNA inside the cells.

As a team...

What do you think the DNA of a banana will look like?

DNA Extraction Lab

Materials

heavy duty ziploc bag
1 banana
10 mL DNA extraction buffer (soapy, salty water)
Coffee Filter
50 mL beaker
popsicle stick
20 mL ethanol
250 mL beaker

Procedure

Place one banana in a Ziploc bag.
Smash/grind up the banana using your fist and fingers for 2 minutes. Careful not to break the bag!!
Add the provided 10mL of extraction buffer (salt and soap solution) to the bag.
Kneed/mush the banana in the bag again for 5 minutes.
Make a filter using the coffee filter and assemble it over your 250 mL beaker
Pour the banana slurry into the filtration apparatus and let it drip directly into your 250 ml beaker.
Measure out 20 mL of ethanol slowly pour cold ethanol into the tube. OBSERVE
Dip the loop or glass rod into the tube where the banana extract and ethanol layers come into contact with each other.
Draw a diagram of what you see.

Back to the Team...

Discuss the following with your team:

Did the DNA look like what you expected?
How did this lab relate to what you know about cells?

Video

What is DNA and How Does it Work?

As you watch...

Consider why scientists want to better understand DNA.

After viewing the video

What is the connection between what you know about cells and how that relates to the passing along of genetic traits.
Consider what might happen if a mistake is made during the process of manufacturing proteins.

Heredity

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