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DNA Jewelry Models

Catherine Sheils Ross



Type of Activity:

  • Hands-on activity/lab

Abstract:

Making DNA Jewelry Models is a portion of a unit on molecular genetics. Using the directions for this hands-on activity/lab helps students construct a model of DNA to learn DNA structure and decode it to better understand protein synthesis. They also have an actual badge of their DNA literacy to wear or use.

Whether a key ring, earrings, bracelet, or necklace, students from fourth grade through adult can do and enjoy this activity. (Even visually impaired students made a model using larger beads.)


Lesson/Activity:

Materials needed:
Teacher:
  • Overhead projector for teacher demo
  • Large pony beads and floral or electrical wire
  • Petri dish to hold demo beads

Students:

  • Seed beads Size E (3mm) or smaller (1.5mm) (sparkle and/or plain)
  • Jewelry wire
  • Key rings, earring wires, clasps
  • Fishing line (for single threading)
  • Small plastic petri dishes (to hold beads)
  • or Science Kit and Boreal Laboratories (who have generously given permission to share my signed over copyright with AE teachers.)
    Kit #45284 for 30 students. $39.50.
    1-800-828-7777
    (and of course I recommend this!-instruction sheet
    has complete graphics etc...)

Method of Evaluation:

The model and the decoding sheet can be quickly checked for accuracy. Since the activity usually takes two hours to complete, I value it at 20-25 points. (10 pts. per hour of mental investment.)


Introduction:

When scientist Rosalind Franklin first saw the model of DNA created by Watson and Crick based on her research, Ms. Franklin exclaimed, "All that matters is the beauty." By creating jewelry models of DNA, you too can experience Ms. Franklin's delight in the beauty of the master molecule of life.

Part 1 - Creating a DNA Jewelry Model

While creating your DNA model jewelry, keep the following hints in mind:

  • Your teacher's demonstration model is there to serve as a guide - refer to it if you need to!

  • Remember that the "uprights" (helixes) in the model will be double threaded. Be sure to pick beads with large enough holes to accommodate both wires. (Can test by using second wire as a blind, as you thread, and pull the extra through after both sugar-phosphate strands are complete.)

  • Using needle-nose pliers to "tie-off" the or twist the ends of each wire will save your fingertips. Also, remember that it is easier to thread the wire directly through the beads while they are in the dish rather than trying to pick up the beads with your fingers.

NOTE: Except where noted otherwise, the procedure of making key chains,earrings, bracelets, etc.. is exactly the same. To make earrings, you might prefer the small (1.5 mm dia.) seed beads; to make keychains, use the larger (3 mm dia.) E-beads.

Procedure:

  • Step 1: Decide which colors you want to use for your model (you will need to choose beads of six different colors - two different colors for the sugars and phosphates, and four different colors for the base pairs.
  • Step 2: To make a keychain, earrings, pendant, or central molecule for a silk cord necklace, bracelet, or ankle bracelet, cut two 15 cm (6") strands of wire. Twist two wires together at one end to prevent beads from slipping off as you string them. These strands of wire will be the helixes, or "uprights" of your DNA model.
  • Step 3: String an equal and even number of beads of alternating colors onto each of the wires, to represent alternating sugars and phosphates. Make sure to start with the same color bead on each wire. When you have strung the beads on each of the wires, twist a loop at the tops of the "uprights" separately to prevent the beads from falling off. Use a minimum of 26 beads for the basic 2 inch molecule. (when twisted) (Leave one inch of "slack" at the top. If you bead right to the top, it'll be very difficult to wire the bases.)
  • Step 4: Cut 30 cm (12") of wire and fold it in half to make an elongated "U". Next, string and center two different colored beads on the wire (or each wire, for earrings), to form the first "rung" or pair of nitrogenous bases.
  • Step 5: Thread each end of the wire with the "bases" beads through the third and fourth beads from the bottom of each of the sugar and phosphate "uprights" and pull tight. You've made the first rung. Be sure that the "u-wire's" ends are even.
  • Step 6: Pull the ends of the bases wire into the center of the ladder and thread two more bases onto one side of the bases wire and take the other bases wire and thread through the two just-threaded bases to make rung at a right angle to the uprights. *** Important!! The bases wires go through each other in opposite directions.*** (These additional complementary bases can be either the same or different colors from the first two sets of bases you used, depending on your personal preference.)
  • Step 7: Continue threading the bases wire up through the next sugar and phosphate on each "upright". Now add two additional complementary bases to the bases wire as you did in Step 6. (At the end of this activity, you will use whatever combination of bases you decided on to determine the amino acids coded for in your model.) Thread the bases wire through the next sugar and phosphate set, and add another base pair.
  • Steps 5-7 repeat!!
    Basic pattern is:
    Up two on both sides
    Add two in the middle
    Cross through the two in the middle
    Up the next two on both sides.
    And again, and again, and again...
  • Step 8: Repeat steps 6 and 7 until you have attached alternating base pairs to each sugar and phosphate set of the "uprights". You should do at least thirteen base pairs to have a large enough molecule to twist.
  • Step 9: Twist all of the wires at the top of the ladder together. You can twist and cut closely or finish with one last pony-bead or E-bead around the point where the wires form the model and the keychain or earring holder connect. If the molecule is loose, untwist the bottom two wires and gently pull on each . This will tighten the sides and make the bases perpendicular to the sides. Retwist together and trim after tightening. (Not too tight because you still need to twist into a double helix!)
  • Step 10: Twist your model into the Double Helix, and tape it onto the accompanying worksheet. Make sure you tape the model so that the top of it corresponds to the order of the colors listed in your color key.
  • Step 11: Then complete Part 2 of your model and decode your model. The jewelry you created will be yours to keep and wear/use after you have handed in this completed worksheet and your teacher has corrected it.

NOTE: Provided you have the optional materials needed, you can also use this pattern to make necklaces, bracelets, tie clips, or other pieces of DNA jewelry. To make larger models, start with two lengths of wire for the sugars-phosphates strands approximately double the desired length of the finished piece of jewelry. String the beads as directed, (Steps 1-9). Hint: Thread the bases in sections--18" of wire in the u-shape for base threading is manageable. Finish off the necklace or bracelet with a barrel clasp, a keychain, or earring wires, as directed in Step 9. Some students might want to make the standard two inch DNA model and use cording to finish into a necklace or bracelet.

Part 2 - Decoding your Model:

_____________________________________________________
DNA Jewelry Model:by:______________
Color key:Model:
A =(Tape here. Make sure that
T =the top corresponds to
C =your color key.)
G =
Sugar =
Phosphate =

(Color code a diagram below, to correspond to the colors of the beads in your model. Then, based on your model, list the m-RNA bases, the t-RNA bases, and the amino acids that the sense strand of your DNA coded for.)

_____________________________________________________
(teacher can use the preceeding as a header on worksheet).


Extensions/Reinforcement:

As part of this unit, we see A&E's "The Race for the Double Helix", read Watson and Crick's Nobel Prize-winning paper and make a showcase to show off their models. (The showcase has pictures of Watson, Crick, and an "I Love Rosalind" picture, directions for the model, and model on the decoding sheet. To display more models, the remainder are on index cards with students' names.)

Some excellent books for student and teacher are:

  • Rosalind Franklin and DNA by Anne Sayre-1975 ISBN: 0-393-00868-1

  • What Mad Pursuit by Francis Crick-1988 ISBN: 0-465-09138-5

  • The Double Helix by James D. Watson-1968 Catalog card #68-16217


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