Making a Candy Model of DNA You and your partner will show how the basic structure and double helix shape of deoxyribonucleic acid is important in the process of replication. To learn how the nucleotides are formed, and how it all fits together. Nearly every cell in our body contains DNA, and it is a very important molecule as it contains important information (genetic information) to tell the cells in our body what to do. DNA is a polymer – that means it is made from lots of small, almost identical, units joined together to make a big molecule. Each unit of DNA, called a nucleotide, contains a sugar molecule (deoxyribose), a phosphate group and a nitrogen base. You and your partner will be graded on how well you follow directions and the quality of your model. DNA Model Materials DNA Part Caramel deoxyribose sugar (S) Twizzlers phosphate group (P) Toothpicks Strong bonds between phosphates and ribose sugars. adenine (A) thymine (T cytosine (C) guanine (G)) Toothpicks hydrogen bonds Information Sides of DNA: The sugar bonds with the phosphate, then the sugar from this unit links with another phosphate and so on until you get a long chain called the sugar-phosphate backbone. The nitrogen bases are adenosine, cytosine, guanine and thymine. These are usually symbolized to A, C, G and T. Each base is attached to its own sugar molecule on one strand and then pairs up with the complementary base on the other strand – turning the two strands into a kind of twisted ladder. The rules for base pairing are very strict. A always pairs with T; and G always pairs with C. Connect the nitrogen bases. The slightly positively charged hydrogen atoms of the bases are attracted to the lightly negatively charged atoms of nitrogen or oxygen on the complementary base. Steps Directions! Be sure that working surfaces and hands have been cleaned before starting this activity, if you intend to consume your models after finishing. Information! Cut Twizzler into small equal size pieces They will be your Phosphates that will bond with sugar. . Use all the material to create your sides first. Color code your Bases. DNA molecules are actually formed by building blocks of nucleotides! Nucleotide is made up of one nitrogen base attached to one ribose sugar molecule which is bonded to one phosphate molecule. Build the DNA model into any sequence of three (3) base pairs. Connect two different colored candies that represent the bases together using the toothpicks. When connecting the base pairs be sure to connect the ones that pair naturally in DNA. For example, adenine pairs with thymine and cytosine pairs with guanine. Connect the “rungs” Grasp the completed molecule by the base pair at each end of the strand twist the structure slightly and you have a DNA model! Be careful it may not twist easily. Wood does not bend. After you demonstrate this to your teacher, you may dispose of or eat your models. This is one case where you may eat your science project, if you have kept everything clean and your teacher gives permission. Be sure to remove toothpicks before you eat!!! Clean up, being sure that no toothpicks or sticky residue is left behind. Wash your hands! Answer the Analysis Question in your composition book. Analysis QuestionsThe whole model represents ___________________ The Sugar is called ______________________ What makes up a single Nucleotide? What are the base pairing rules for DNA_________________________ Write down the sequence of both of your strands. Transcribe one of your strands to represent M RNA.
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