DNA Structure: Gumdrop Modeling
Basic Version
DNA has a very specific structure that allows it to coil, divide, copy itself, etc. to
be inside every cell in your body. Can you imagine DNA at all? Does it look like a giant
fluffy bunny? In this lab you will create a model so you can form an idea of what DNA
looks like, where it is found, and how big (or small) it actually is.
Important Concepts:
 DNA stands for Deoxyribonucleic Acid
“De” = Without
“oxy” = refers to oxygen
“ribo” = refers to the sugar molecule (deoxyribose in DNA )
“nucleic” = referring that it lies within the nucleus
 DNA is the genetic material inside your cells; it is the “instructions” inside the
nucleus of every cell that tell your cells how to grow.
 DNA is made up of many nucleotides. A nucleotide is made up of one
phosphate molecule, one sugar molecule, and one base.

http://www.mhhe.com/biosci/esp/2001_gbio/folder_structure/ge/m4/s1/gem4s1_1.htm
 DNA has only 4 bases: Adenine, Thymine, Cytosine, and Guanine. Each base
corresponds with only one other base. In DNA, Adenine pairs with Thymine
(vice versa), and Cytosine pairs with Guanine (vie versa), so you will never find
Adenine with Guanine, or Cytosine with Thymine.
Materials: (group of up to 4)
1)
DOTS Candy & Crows (also a product of Tootsie): ** NOTE: Material contains
corn syrup!
2)
3)
 Green = Phosphate
 Black = Sugar Use CROWS black licorice
 Yellow = Adenine
 Pink = Thymine
 Orange = Cytosine
 Red = Guanine
20 Toothpicks
1 meter of yarn
Procedure
1. Take 12 green, 12 black, 4 yellow, 4 pink, 2 red, 2 orange (DOTS) and 20 toothpicks
2. Cut all of your toothpicks in half – you will use these to bond one candy to another.
3. Set aside 6 green, 6 black, 2 yellow, 2 pink, 1 red, 1 orange (DOTS) – you will use
those later on.
4. With your colors create 6 nucleotides; each one must have one black, one green, and
either a red, yellow, blue, or orange.
What three things is a single nucleotide made up of?
5. Your green should be on the outer part of your nucleotide, while the black is in
between your base (pink/yellow/red/orange) and green. Check your nucleotides!
http://academic.brooklyn.cuny.edu/biology/bio4fv/page/molecular%20biology/dna-structure.html
6.
Make sure your sugar is bonded to only one base. Check your model.
What base does the yellow candy represent? Red? Pink? Orange?
7. Once you have your nucleotides, pick one (any one), and look at its base. Find the
nucleotide that has the base that should be paired with the one you chose. With the
toothpicks bond the nucleotides, connecting bases (use one toothpick in between
each candy).
http://1mkturin.files.wordpress.com/2009/03/dna-colored.gif
http://intra.stgym.dk/sa/3_chem1.gif
Why do you think it is important that bases are paired with only one other base?
8. Choose another nucleotide. Attach this nucleotide to the already paired ones.
Nucleotides are bound together through a phosphate. Make sure that the phosphate
of the new nucleotide is not touching another phosphate, or sugar touching another
sugar, and that the base is towards the center.
9. Continue attaching nucleotides until you have used your six nucleotides to make
three (3) correctly bound pairs.
DNA
http://picsdigger.com/domain/studentsguide.in
10. Compare your model to the diagram below. Does it look alike? Notice how one
strand starts with phosphate but ends in sugar, while the other starts with sugar but
ends in phosphate.
http://www.biologycorner.com/resources/DNA_antiparallel.gif
In this lab you only made 6 nucleotides and three pairs. In real life, do you think
DNA in your cells is made up of only 3 nucleotides? How many do you think there
are?
1. Take the string of yarn. It should measure 1 meter. This is how long DNA would
be in real life if you stretched it out.
2. Now, take the yarn and compact it so that it measures 1 millimeter, do you think
you can do it?
3. Now try to make your 1-millimeter yarn 10 times smaller. This is the size of your
cell’s nucleus: 10 microns long. It takes 100 microns to make one millimeter.
Try to squish this piece of yarn another 10 times (not possible, right?) DNA is 1 micron
big inside the nucleus, which means it’s another 10 times smaller. Why do you think
DNA is so small?
Part 2 – Replication Process
Important Concepts:
 The replication process allows a cell to divide in order to create copies of itself
for new cells.Although you start off with one cell with DNA, you end up with
two.DNA Helicase: An enzyme in DNA that “cuts” or “unzips” the DNA strands
in preparation of the replication process
http://4.bp.blogspot.com/_8Rm_kFNfDDg/SadUClLoQ7I/AAAAAAAAA98/oWWpjdvvzwc/s400/DNA_unzi
pping_Efjc_Ewlc.png
 Replication Fork: The meeting point between the unwound part and the open
part.
http://faculty.clintoncc.suny.edu/faculty/michael.gregory/files/Bio%20100/Bio%20100%20Lectures/DNA/dna.htm
 DNA Polymerase: A DNA enzyme in charge of attaching, or completing, the
complementary bases of the strand it is completing.
Materials:
1)
2)
3)
4)
DNA Model
1 pair of Scissors
Remaining candies: 2 pink, 2 yellow, 1 orange, 1 red
Remaining toothpicks
Procedure:
1. Take the Scissors and cut your model right down the middle (separating the bases
from each other). Now you have two incomplete strands with splinters at the end of
each.
What part of the replication process do the scissors represent?
2. Start with the strand that begins with phosphate but ends in sugar and from bottom to
top connect the correct base to each splintered end (if you have A on one side, you
are attaching T, and make sure you are using the right color candy!)
What enzyme are you representing now?
3. What molecules do the green and black candies represent?
Now you should have two complete DNA strands, even though you started with
only one! Now separate the remaining base pair and complete both strands.
How many complete DNA strands do you have now?
Concept Questions:
1) True / False , the purpose of the replication process is to create new cells with
DNA.
2) What is DNA made up of?
3) Approximately how big is DNA?
4) Your DNA is different from everyone else’s
True / False
5) DNA stands for:
a. Dumb Newt Association
b. Demoniclyrapid nickel Acid
c. Deoxyribonucleic Acid
d. Deoxygenated ribose in Nucleus Acid
6) Pair these letters with their correct pairing letters:
A A C T A A G G T A C A A T C C G C A
PART 3 – DNA & RNA
Where is DNA found & how is it used?
Hypothesis:
Important Concepts:
 There are two types of cells; Prokaryotic cells and Eukaryotic cells. While
Eukaryotic cells have a protected nucleus and many organelles (specialized parts
of a cell), Prokaryotic cells don’t have a nucleus, and have very few organelles.
 Human cells are Eukaryotic, so they have a cell membrane (that keeps
everything inside), cytoplasm (a jelly-like substance inside where the organelles
are all spread out), and a nucleus in the center.
http://2.bp.blogspot.com/_lcqHdkGk3cs/Sdt9Oqn-5FI/AAAAAAAAATs/veXMRCgL_94/s400/human-cell.jpg
 RNA is a single-stranded molecule that contains the same structure and
information as DNA. It is also composed of a sugar (ribose), phosphate, and has
4 types of bases, though instead of having A, T, C, G, it has U in place of T.
DNA
RNA
http://1mkturin.files.wordpress.com/2009/03/dna-colored.gif
http://www.biologycorner.com/bio1/DNA.html
 RNA moves across the nucleus into the cytoplasm to transport the code from
DNA for the creation of proteins. Proteins are what come together to form our
traits, without them there would be something seriously wrong with us.
http://www.biologycorner.com/bio4/notes/gene-expression.php
Materials:
1.
2.
3.
4.
DNA model
1 large container
Water Source
1 sandwich bag
Procedure:
1. Which item represents which part of the cell? (Draw a line matching the material
to the cell part)
1. Large Container
a. Cytoplasm
2. Sandwich Bag
b. Nucleus
3.Water
c. Cell Membrane
2. Pour water
into the large container (for the sake of precautions,
fill only halfway)
3. Place the DNA model in the plastic bag, and seal it tightly
What do you think the nucleus’ role is? Where is DNA stored?
4. Place the plastic bag in the water-filled container
In this lab you placed the DNA inside a plastic bag before placing it in the liquid.
Why do you think DNA is not found floating around in the cytoplasm?
5. Cut a hole 6 cm wide on a corner of the sandwich bag. The nucleus inside a cell
does not open and close at all; instead, it has small pores on its surface.
6. Without tearing a bigger hole, try getting your entire DNA model out of the bag.
Does it fit? Cut a hole 6 cm wide on a corner of the sandwich bag.
7. Gently, pull out only half of the DNA model through the hole.
What do you think this single-stranded molecule could be?