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Candy DNA
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DNA Science: Candy DNA Model
OVERVIEW
The purpose of this activity is to construct a DNA model using candy pieces. It will contain all of the
parts of real DNA. This activity will provide a foundation for further study of DNA and molecular biology
concepts.
GRADE LEVEL: 7‐12
OBJECTIVES
The students will:
• Describe the structure of the DNA molecule.
• Explain the rules of base pairing.
• Represent the structure of DNA in a candy model using different candies and colors of candies
to accurately represent the sugar phosphate backbone and the nucleotide base pairs.
TIME ESTIMATE: 45 minutes
NEW GENERATION FLORIDA STATE SCIENCE STANDARDS
Grade 7
Big Idea 3: The Role of Theories, Laws, Hypotheses, and Models
• Benchmark (SC.7.N.3.1): Identify the benefits and limitations of the use of scientific models
Big Idea 16: Heredity and Reproduction
• Benchmark (SC.7.L.16.1): Understand and explain that every organism requires a set of
instructions that specifies its traits, that this hereditary information (DNA) contains genes
located in the chromosomes of each cell, and that heredity is the passage of these instructions
from one generation to another.
Grade 9‐12
Standard 3: The Role of Theories, Laws, Hypotheses, and Models
• Benchmark (SC.912.N.3.5): Describe the function of models in science, and identify the wide
range of models used in science.
Standard 16: Heredity and Reproduction
• Benchmark (SC.912.L.16.3): Describe the basic process of DNA replication and how it relates to
the transmission and conservation of the genetic information.
• Benchmark (SC.912.L.16.9): Explain how and why the genetic code is universal and is common
to almost all organisms
NATIONAL STANDARDS
Content Standard C: Life Science 5‐8
• Reproduction and Heredity: Every organism requires a set of instructions for specifying its
traits. Heredity is the passage of these instructions from one generation to another.
Developed by Julie Bokor jbokor@ufl.edu
Candy DNA
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Content Standard C: Life Science 9‐12:
• The Cell: Cells store and use information to guide their functions. The genetic information
stored in DNA is used to direct the synthesis of the thousands of proteins that each cell
requires.
• The Molecular Basis of Heredity: In all organisms, the instructions for specifying the
characteristics of the organism are carried in DNA, a large polymer formed from subunits of
four kinds (adenine (A), guanine (G), cytosine (C), and thymine (T), with uracil (U) in place of T in
RNA). The chemical and structural properties of DNA explain how the genetic information that
underlines heredity is both encoded in genes (as a string of molecular ‘letters’) and replicated
(by a templating mechanism). Each DNA molecule in a cell forms a single chromosome.
KEY TERMS
Base pair: two nucleotides on opposite complementary DNA strands that are connected via hydrogen
bonds (abbreviated bp). The size of an individual gene or an organism's entire genome is often
measured in base pairs because DNA is usually double‐stranded. The human genome is estimated to
be about 3 billion base pairs long and to contain 20,000‐25,000 distinct genes.
Deoxyribose: A sugar (C5H10O4) that is a constituent of DNA. It is ribose (found in RNA) missing an
oxygen in the 2’ position.
Gene: A hereditary unit consisting of a sequence of DNA that occupies a specific location on a
chromosome and determines a particular characteristic in an organism.
Nucleotide: A nucleotide is composed of a nitrogenous base and a five‐carbon sugar (either ribose in
the case of RNA or 2'‐deoxyribose in the case of DNA), and a phosphate group.
Phosphate ion: consists of one central phosphorus atom surrounded by four oxygen atoms in a
tetrahedral arrangement. The phosphate ion carries a negative three charge and confers an overall
negative charge to the DNA molecule.
Protein: Any of a group of complex organic macromolecules that contain carbon, hydrogen, oxygen,
nitrogen, and usually sulfur and are composed of one or more chains of amino acids. Proteins are
fundamental components of all living cells and include many substances, such as enzymes, hormones,
and antibodies that are necessary for the proper functioning of an organism.
BACKGROUND INFORMATION
DNA provides the instructions for building and operating all living things. The DNA instructions are
divided into segments called genes. Each gene provides the information for making a protein, which
carries out a specific function in the cell.
A molecule of DNA (Deoxyribonucleic Acid) is composed of two backbones and four types of chemical
bases (nucleotides). A chain of alternating phosphate groups (phosphorous and oxygen) and
deoxyribose (sugars) forms the backbone. Each sugar molecule in the backbone provides an
attachment site for one of the chemical bases. The four types of chemical bases are: adenine, thymine,
cytosine and guanine. They usually are represented by their first letters: A, T, C and G. The bases form
pairs in a very specific way: A always pairs with T, and C always pairs with G. A pair of bases is
connected by hydrogen bonds; A and T form a double hydrogen bond, and G and C form a triple
hydrogen bond.
Developed by Julie Bokor jbokor@ufl.edu
Candy DNA
DNA Science Page 3
A DNA molecule is often compared to a ladder, with the two
backbones forming the sides of the ladder and the base pairs
forming the steps, or rungs. However, instead of a straight ladder,
DNA looks like a twisted ladder, known as a double helix (“double”
for the two backbones). The DNA sequence is the consecutive order
of bases on one side, or strand, of the twisted ladder. The other
strand has a complementary sequence determined by the base
pairing rules.
The specific matching of the base pairs, A with T and C with G,
provides a way for exact copies of DNA to be made. This process is
called DNA replication. In DNA replication, the double helix ladder is
untwisted and breaking the hydrogen bonds between the base pairs
separates the two strands. Next, two new strands are made by
reading each side of the DNA ladder, one step (base) at a time. At
each step, the matching base fills in (with its associated sugar and
phosphate) to complete the rung and lengthen the new DNA strand.
When the process is complete, there are two identical DNA double
helices, each containing one original and one new strand.
DNA replication is an important part of the cell division process. Before a cell divides, it first duplicates
its DNA so that the new cell will have the same genetic information. The specific base pair matching
during replication ensures that exact DNA copies are made.
MATERIALS
For each student (or pair): For 25 candy DNA sets:
• 10 Gummy Savers (preferably the same color) • 5 bags (7.7oz) Gummy Savers
• 2 Twizzlers (cut into 12 equal pieces) • 1 bag (12.4oz) Rainbow Twizzlers
(Note: If regular Twizzlers used, cut ends and discard; if using • 4 bags (20oz) Spice drops
rainbow twizzlers, the entire candy can be used. • 50 chenille stems
Note: small round pasta can be substituted) • 50 wooden craft sticks
• 10 spice/gum drops (or colored marshmallows): • 125 toothpicks (round)
2 orange, 2 red, 3 green, 3 yellow • 25 plastic Ziploc bags or packaging
(Note: If different colors are substituted, change the • 25 student handouts
information on the student worksheet accordingly.) • Colored pencils (optional) to be shared
• 2 chenille stems (pipe cleaners)
• 2 wooden craft sticks (or Popsicle sticks)
• 5 Toothpicks
• Scissors (if students will be cutting the Twizzlers on their
own)
• Plastic Ziploc bag
• Student handout
• Colored pencils
Developed by Julie Bokor jbokor@ufl.edu
Candy DNA
DNA Science Page 4
ADVANCE PREPATION
1. Cut the Twizzlers into the smaller pieces for the students (most easily done by cutting through
many with a large knife)
2. Prepare a Ziploc bag for each student or pair or lay out all of the materials the day of the activity
and let the students collect them in their Ziploc bag.
3. Create your own DNA candy model to use as an example.
LESSON PROCEDURE
1. (20 minutes) Begin lesson with a discussion on the structure and components of DNA. Make sure to
cover the ‘backbone,’ base pairs, hydrogen bonds, and the twisted double helix.
2. (5 minutes) Discuss what each material in the activity represents in the DNA structure:
• Twizzlers (or pasta): phosphate groups
• Gummy savers: deoxyribose (sugars, which have ring structure)
• Spice/gum drops: nucleotides (chemical bases)
o Green‐ G, Yellow‐ C, Red‐ A, and Orange‐ T (change as needed based on the color
spice/gum drops being used)
3. (2 minutes) Hand out student sheets explaining how to assemble the model.
4. (10‐15 minutes) Students will create their models
ASSESSMENT
Students should be evaluated on their ability to recall and apply the information gained on the
structure of DNA.
ACCOMODATIONS
If a student is unable to assemble the DNA model individually, have students work in pairs.
Use the interactive DNA model building at
http://learn.genetics.utah.edu/content/begin/dna/builddna/
RESOURCES
• http://learn.genetics.utah.edu/ (background information and image)
• http://en.wikipedia.org/wiki/Main_Page (background information)
ADDITIONAL RESOURCES
• http://www.dnai.org/
• http://nobel.scas.bcit.ca/resource/dna/
• http://molvis.sdsc.edu/dna/moredna.htm
EXTENTION ACTIVITIES
• Have Your DNA and Eat It Too: Another version of a candy DNA model that includes
instructions on taking the candy DNA through the process of transcription and translation.
http://teach.genetics.utah.edu/content/begin/dna/eat_DNA.html and
http://teach.genetics.utah.edu/content/begin/dna/reading_DNA.html
Developed by Julie Bokor jbokor@ufl.edu
Candy DNA
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• Have students investigate the process of putting the pieces of DNA together and the scientists
who played a part.
http://undsci.berkeley.edu/article/dna_01 and
http://news.bbc.co.uk/2/shared/spl/hi/sci_nat/03/dna50/timeline/html/default.stm
• Use DNA technologies and explore gel electrophoresis either virtually, with a dry lab, or wet lab
activity
Developed by Julie Bokor jbokor@ufl.edu
Candy DNA
DNA Science Page 6
Candy DNA Model: Student Procedure
Your task is to construct a DNA model using candy pieces. It will contain all of the parts of real
DNA.
A DNA molecule is often compared to a ladder, with the two backbones forming the sides of
the ladder and the base pairs forming the steps, or rungs. To create the two backbones you will
need to alternate Twizzler pieces (representing the phosphate groups) and Gummy Savers
(representing the deoxyribose) on a pipe cleaner. Leave room at both ends of the pipe cleaner
to wrap around the craft sticks at the end (this will hold your model together).
For this model, we will be using a specific sequence. One strand of the DNA molecule is given in
the table below. Fill in the bases that will be paired with the ones given. Remember base
pairing: A always pairs with T and G always pairs with C.
Use the following colors to represent the bases: A (adenine) red
T (thymine) orange
C (cytosine) yellow
G (guanine) green
Complete the base pairing in the chart below. You may use colored pencils if you like. This is
the DNA sequence you are to create.
A
G
G
T
C
To create the base pairs, you will place two gumdrops on a toothpick. Because the bases attach
to the sugars in the backbone, insert the toothpick into the Gummy Savers on both sides. After
you have attached the pipe cleaners to the craft sticks, your model is done!
Gently twist your model to accurately represent the twisted double helix of a DNA molecule.
Developed by Julie Bokor jbokor@ufl.edu
