California Academic Content Standards (Reinforced)

• S.9-12.LS.4.b Students know how to apply the genetic coding rules to predict the sequence of a...1

• DNA Name - Hooks / Set

  As students come into class they are given the challenge of changing their first name into DNA. The worksheet guides them through writing their first name, then using the alphabet list to find the sequence for their "DNA Alias" or "DNA name". The challenge part of the activity asks them to use a codon chart from their textbook to match their DNA sequence to the appropriate codons, and answer a few review questions from our protein synthesis unit. The worksheet challenges students to use base pairing rules, write complementary DNA strands, and translate their "DNA name" into an amino acid sequence.

  • DNA Alias Worksheet [ Download ]
  • Codon Chart [ Download ]
• Review DNA Structure - Lecture

  Randomly calling on students, review the base pairing rules (adenine to thymine, and guanine to cytosine). Remind students in that the letters with straight lines (A and T) always go together and the letters with curved lines always go together (C and G), except in RNA, where T becomes a U. Review with students that DNA has a double helix structure, that it looks like a ladder that twists upon itself. On the board, the teacher may use their last name as an example, and call on students to walk  through each part with my name. This creates a sample DNA strand for modeling how to make the ornament.
• DNA Ornament - Demo / Modeling

  The original model came from a RAFT activity, and kits are available. Attached is a PDF of that activity along with the worksheet that is use with the modifications made to make it specific to their class. Students will be making their model using pipe cleaners and beads to make their ornament. It is sometimes helpful to have a finished model to show students, and one to demonstrate the steps with them.

  
  1. Pipe cleaners, black and white pony beads are used to represent the sugar phosphate backbone and other colors of pony beads are used to represent the nucleotides- these colors change every year based on what I can find. I make a color key on the board, based on what colors I am using.

  
  2. Going back to the strand made with the teacher's name (the example is still on the board), walk students through how to make the model. 

  3. First, students fold the pipe cleaner in half, then they add a white bead, then a black bead, and then a bead representing the first letter of my "DNA name", followed by a bead that complements the first one, a black bead, and then a white bead- for a total of 6 beads.

  
  4. Next add 4 beads to one side of the pipe cleaner- sugar, next base pair, sugar.

  
  5. This is the hardest step for most students. By folding the pipe cleaner you have two ends, take the end that does not have the beads and run it through the 4 beads on the other side. This creates the first loop- look at figure 3 in the handouts.

  
  6. Add a phosphate group bead to each side and then repeat the steps.

  
  7. Continue to repeat the steps until the strand represents the entire first name.

  
  8. If students run out of pipe cleaner length, they can add more by twisting a new one onto the ends of the old one.

  
  9. At this point, students will need to obtain a "stamp" from the teacher (see below). To finish the ends twist the two sides together to seal the bottom and cut off any excess.

  
  10. To twist the helix, hold onto both ends and twist, the pipe cleaners will naturally twist creating the twisted double helix shape.

  
  11. To turn it into an ornament, place a hook around the top and allow students to hang on the classroom tree- you can also loop masking tape with the students name on the bottom so they can identifty theirs when it is time to take them home.

  • RAFT Modeling Directions [ Download ] Directions on how to create model from RAFT.
• DNA Ornament - Lab / Shop

  Students will work on their own DNA model. The lab sheet below guides them through the steps. During this time, the teacher can walk around the room and help the students. Many of them will become confused at the pulling the pipe cleaner through step, review how to do this once with them normally helps. It is important to remind students to use their DNA alias as their base pair sequence. Students are usually about halfway through the first period when they begin their models. usually they finish their models on day 2.

  • DNA Ornaments Student Directions.doc [ Download ]
• Stamp Point - Assessment

  At step 9 of the student directions, students are instructed to raise their hand to obtain their stamp. It is important to check the students model to ensure they are understanding the directions.  The teacher may select two or three base pairs and make sure they are correct. If they are correct, and the model is put together correctly, a stamp is placed in the "Stamp" box on the student's assignment sheet.  Twist the ends together to finish the model off and use wire cutters (jewelry type) to trim the ends and give the student a piece of masking tape and a hook. They are instructed to write their name on the tape and wrap it around the bottom and place the hook on the top and hang it on the tree.
• DNA Coloring Sheet - Closure

  As students finish I have thier DNA model complete the attached coloring and reading sheet. It gives a basic review of DNA structure and function. Students color the DNA model and answer the questions.

  • DNA Coloring Sheet and Review Questions [ Download ]