Fruit loop DNA
Created by Erika Styer
October 2010
Time: About two 39 min periods
Grade Level: 7th grade
Concepts: Structure of DNA & Basic intro to Nucleic Acids
Possible Do First Questions:
1) Does your desk have DNA? (allow debate over what desk is made of and whether or not DNA could be
preserved in dead material. May have to re-explain non-living vs dead)
2) Do rocks?
3) Do trees?
4) What defines something as living? (review of 8 functions of life. Ask what function of life does DNA fit
into. Explain how DNA is part of reproduction and growth)
Follow up activity:
In my seventh grade team, I connected the DNA strands of each of the periods (5) together to make one strand
about 130 feet long. I hung the strand down our team’s hallway. I had each lab station research 3 DNA facts
and record sources. Each period voted on two overall facts they wanted to represent their period. I hung each
periods’ DNA fact next to their part of the DNA strand. I made a poster/banner of a very basic description of
the activity to hang at the entrance to the hallway. I had very positive feedback from other teachers and
administration about the ‘cool-looking’ display of DNA. The 7th graders took pride and showed off their part of
the DNA strand to friends as they walked down the hall. This also allowed for a cool transition into
chromosomes. I wound up the long DNA strand into a yarn bundle and it became a metaphor of a
chromosomes.
Nucleic Acids:
the building blocks of DNA
Introduction
In this unit we have been learning about the different kinds of compounds that make up organic matter. So far
we have learned about Proteins, Carbohydrates, and Lipids. Today we are learning about the fourth kind of
compound called Nucleic acids.
Each of our bodies is very unique because of Nucleic Acids like DNA (deoxyribonucleic acid) and RNA
(ribonucleic acid). DNA is made up of four different bases Adenine, Thymine, Cytosine, and Guanine.
Each of these four bases has a partner base they always pairs with. The different sequences of the
four bases code for our bodies to make us very different from one another. So DNA determines how
we look on the outside and how our body works on the inside.
Today we will be learning about the structure of DNA. DNA is arranged in a double helix. It looks like a rope
ladder which someone has twisted. The ladder connected by bonds between pairs of bases. There are bonds
side-to-side between two bases that make the ‘rungs’ of the ladder, called hydrogen bonds. There are also
bonds running up and down which make the sides of the ladder, these are phosphate bonds.
Today, with the help of our delicious generic brand Fruit Hoops, we
will be making our own models of the structure of DNA!
The four bases will be represented by four colors of fruit loops (RED, BLUE, GREEN, and
YELLOW). Just like real nucleic acids, each color of the fruit loops has a partner.
Red bonds to Blue
Yellow bonds to Green
Hydrogen bonds = black yarn
Phosphate bonds= white yarn.
Lab Procedure:
1) Separate bases (fruit hoops). Each student should take a small pile of fruit loops and sort out the Red,
Blue, Yellow, and Green fruit loops. The other color fruit loops can be put back in the container.
2) Make base pairs. Each student should take two fruit loops and ‘bond’ the two bases
together by tying them with a black piece of yarn (Hydrogen bond). Remember, like
bases, certain fruit loop colors can only pair with certain other colors.
3) Connect your four base pairs. Each student should connect the base pairs with the white yarn
(Phosphate bond) to make one short ladder with four rungs.
4) Combine your piece of DNA with your lab partners. Tie your piece of DNA onto your partners
with white yarn. You should now have a piece of DNA with many base pairs.
5) Stretch and Twist your DNA. Have two people hold the DNA, one at each end, and slowly twist the
structure. This is what a double helix strain of DNA looks like!