Replication+Activity

In this activity you will assemble a paper DNA model and then use the model to demonstrate how one strand of DNA is replicated to produce two strands. Producing two strands of DNA from an original strand of DNA is called replication. To summarize: you will cut out the paper shapes, assemble them into a ladder shape, and move them as shown in the animation below.

DNA consists of two side strands connected by complementary bases. Nucleotides are the units that make up DNA. Nucleotides have three parts. The shapes on the paper consisting of an oval and a pentagon with an "arm." These three shapes represents the three parts of a nucleotide. The shape of DNA can be compared to a ladder. The circles and pentagons represent the sides of the DNA molecule. The arms represent the complementary bases. The four different shapes on the end of the arms represent the four different kinds of bases found in DNA. The shapes that "fit together" at the ends of arms represents complementary bases. (The actual shape of DNA is called a double helix and looks like a twisted ladder.)

Cutting: Separate the shapes on the paper. The steps below are a quick way to do this. 1. Make 4 vertical cuts close to the circles and pentagons on the side opposite the arms. 2. Make two parallel cuts, one right next to the circle and the other right next to the pentagon. The shapes should now be separated. 3. For each shape, make a cut from the corner of the pentagon to the end of the arm. 4. For each shape, make another cut from the edge of the circle to the end of the arm. 5. Cut out the shape at the end of the arms.

Building: Put the nucleotide shapes into the shape of a DNA ladder. 1. Put four nucleotide shapes with the circle of one next to the pentagon of another. Use one of each kind of Nucleotide. Note, there are four different arm ends. 2. Like puzzle pieces, place four more nucleotide shapes across from the first four so the arm ends fit together. Arm ends that fit together are complementary. You should how have a DNA ladder with four steps.

Replication: Move the DNA model pieces similarly to the process of replication. Start with one DNA ladder with four steps. 1. At the arm ends, "unzip" two nucleotides of your DNA ladder. This "Y" shape is called a replication fork. 2. Like puzzle pieces, fit more nucleotide arms to these exposed arms. This is the start of two new DNA side-strands. 3. Unzip the remaining two nucleotides of your DNA ladder. 4. Like puzzle pieces, fit more nucleotide arms to the exposed arms. Now you have two identical DNA ladders and you just simulated the process of replication.

Nucleotide Sheet:



If you want to know all the details about replication, investigate the information below.

http://www.wiley.com/college/pratt/0471393878/student/animations/dna_replication/index.html

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