Download DNA Model and Replication Name: Objective: The students will

DNA Model and Replication
Name:
Objective: The students will show how the basic structure of DNA is important in the process
of DNA replication.
Materials:
2 red licorice strands, cut into 6 pieces each
2 black licorice strands, cut into 6 pieces each
6 of each color of mini marshmallow or gumdrop
Wooden toothpicks
Part One: Procedure- DNA Model
1. Assign one nitrogen base to each of the four colors. For example: green=adenine,
orange=thymine, red=cytosine, yellow=guanine
2. Get the materials listed above.
3. Prepare 6 individual nucleotides: use toothpicks to connect one black to one red
twizzler piece. Then add one marshmallow perpendicularly to the black candy.
4. Assemble nucleotides into a polynucleotide strand by connecting the red piece of one
nucleotide to the black of another. Continue until a strand of six nucleotides has been
constructed. Once this is completed, all of the reds and blacks should be in alternation
in a straight line; the marshmallows should be sticking out at a perpendicular angle from
the blacks.
5. Assemble a strand which is complementary to the strand which you have already built.
Place the second strand next to the first so that the “bases” touch. Make sure that the
correct bases are across from each other in the new strand.
Questions:
1. What does each of the parts of your model represent?
Red twizzlerBlack twizzlerorange marshmallowred marshmallow –
yellow marshmallow green marshmallow 2. Describe the actual shape of a DNA molecule.
3. Which nitrogen bases are paired together? (Check your model, is it correct?)
_______________ and ______________
__________________ and ________________
4. Where is DNA found in the human body?
Part 2: Procedure-DNA Replication
1. To show replication of the DNA molecule, “unzip” the double strand. Assemble
the proper nucleotides, one by one. One side should be assembled first then the other
side.
2. After you have completed the replication of the DNA molecule, show it to your
Teacher and get signed off.
Teacher Sign Off:
Questions:
1. Which two molecules make up the “side” of the DNA molecule?
2. Which molecules make up the “rungs” of the molecule?
3. How does the model you constructed differ from an actual DNA molecule, besides being
made of candy?
4. Describe how the replication process creates two exact copies.
5. There are about 4,000,000,000 base pairs in a human’s DNA. Sometimes
mistakes are made when replication occurs causing a mutation. How might a
mutation be made?
Part 3: Procedure-Combining 2 DNA Models
1. Find another group in the room and exchange your replicated DNA. Add their
DNA to the bottom of your original DNA. Answer the question below.
Questions
1. How many base pairs were there in your model after you combined it with the
other model?
2. How many codons or 3 base pair units were in your finished model?
3. How many amino acids could your combined model code for? Remember that both
sides of the DNA molecule can code for amino acids.
4. Only one of the strands of DNA actually codes for protein. Why do you think there are
2 strands on one DNA molecule?
Part 4: Procedure-Disassembling your model
After you have finished, take apart all the pieces of your model and return them to where you
got them. Eat at your own risk!! Remember where they have been!!