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To help further understand how DNA is structured, build a model of it. This is a
simplified model of DNA, but it will still give you the general idea of how the
sugars, phosphate groups, and bases all connect together to make the famous
double helix shape of DNA. You can make a model out of a variety of
materials. Here's how you can do it with candy.
- Red and black hollow licorice sticks
- Gummy bears
- Small white marshmallows
What To Do:
- Cut the red and black licorice sticks into one inch strips.
- Make two equal lengths of licorice strands by threading the pieces of
licorice onto the string, alternating the red and black pieces.
- Gather together four different colors of gummy bears, the marshmallows,
and the toothpicks.
- Pair two colors of the gummy bears together and then pair two
other colors together. For example, red and orange gummy pairs could be paired
together, and green and yellow ones be paired together.
- Take a gummy bear and thread it onto the toothpick. Thread the
marshmallow onto the toothpick so that it is in the center of the toothpick
and next to the gummy bear. Thread the complementary gummy bear onto the
toothpick so that it is next to the marshmallow. You should now have a
toothpick with a gummy bear-marshmallow-gummy bear centered on it.
- Repeat step five to make more gummy bear-marshmallow toothpicks, making
sure the gummy bears are matched with their complementary colors. Make as
many of these toothpicks as you have red pieces on one of your licorice
- Take one strand of licorice and start attaching the gummy
bear-marshmallow toothpicks to it, connecting one of these toothpicks at
each of the red pieces on the strand. Then, take the second licorice strand
and connect it to the other side of the toothpicks. Again, connect the
toothpicks to the red pieces of licorice. You should end up with a "ladder"
with the red and black licorice stands making the sides of the ladder and
the gummy bear-marshmallow toothpicks making the rungs of the ladder.
- Hold your candy ladder up and turn the top counterclockwise to add
twists to the ladder.
You have just made a candy model of a strand of DNA. The red licorice
represents the sugar deoxyribose, the black licorice represents the phosphate
groups, and together they represent the sugar-phosphate backbone of DNA.
The gummy bears represent the bases that make the code of DNA. The four
different colors are used to represent the four different bases found in DNA:
adenine (A), thymine (T), guanine (G), and cytosine (C). It doesn't really
matter in your model how much of a base you use or where it is placed in the
strand, but it is important that bases are paired up correctly: A with T and G
with C. (In real DNA the order does matter as that determines what type of
organism it is and how functional it will be.)
The marshmallow in between the gummy bears represents the hydrogen bonds
connecting the bases. This is the point at which the DNA strands break apart
during replication and where the new strand connects to the original strand.
Twisting the ladder at the top in a counterclockwise direction gives the DNA
model its true shape: a right-handed double helix.
Read more about DNA here.