1. Explain the structure of DNA – use the terms nucleotides, antiparallel strands, and complimentary base pairing.
As demonstrated in the picture below, DNA is made up of molecules called nucleotides. (white pipe cleaners) Each nucleotide contains a phosphate group , a sugar group and a nitrogen base. The four types of nitrogen bases are adenine (A=yellow), thymine (T=blue), guanine (G=purple) and cytosine (C=green). The order of these bases is what determines DNA’s instructions, or genetic code. Strands of DNA are anti-parallel, meaning they run side by side, but are not read in the same direction. Each base has a pairing opposite to itself (pyramidine to purine) . 
2. How does the activity help model the structure of DNA? What changes could we make to improve the accuracy of this model? Be detailed and constructive
I think it helps us understand tangibly the shape of DNA. I think in the future if it were possible to find materials that are slightly larger would be more helpful, as working with the small ones became quite difficult. Also, I know there are beads with letters on them, so maybe using those instead of colours.
3. When does DNA replication occur?
DNA replication occurs in Interphase. It occurs before new cells are formed, because all organelles and genetic information must be doubled before the split.
4. Name and describe the 3 steps involved in DNA replication. Why does the process occur differently on the “leading” and “lagging” strands?
Unwinding and Unzipping: The DNA molecule twists out of its double helix form and into a ladder. DNA helicase (green playdough) proceeds to break the hydrogen bonds between the base pairing and create two separate “strands”
Complimentary base pairing: Free floating nucleotides from the nucleus move into place and form new hydrogen bonds with the existing nucleotides on the separated strands. This is allowed by DNA Polymerase (red playdough).
Joining: Two DNA strands are formed using covalent bonds. The leading strand continuously bonds the nitrogenous bases as DNA unzips, while the lagging strands bonds together in segments with the help of DNA ligase (blue playdough). The processes are different on the strands because the strands are anti-parallel, and are read from different ends.
3. The model today wasn’t a great fit for the process we were exploring. What did you do to model the complimentary base pairing and joining of adjacent nucleotides steps of DNA replication? In what ways was this activity well suited to showing this process? In what ways was it inaccurate.
We modelled the base pairing as best as we could using a separate sheet of white paper to cover the rest of the 3rd and 4th blue pipe cleaner. We tried our best to demonstrate the difference between the lagging and the leading strands, but it is very hard to show bonding in segments rather than all at one. In the future, I believe maybe a time lapse video would show how DNA is properly replicated, but the use of pipe cleaners worked well for the activity.
