1. Explain the structure of DNA

Every DNA strand is essentially a large polymer made of molecules called nucleotides. Phosphate and nitrogen are the bases of DNA. The types of bases include adenine, thymine, guanine and cytosine and these determain the genetic code. These for bases are shown in the pictures as the purple, blue, yellow and green beads. These are attached to H bonds which are the white strands and are connected to the backbone, the blue pipecleaner. In between in each H bond there is phosphate, or pink bead. Every DNA code starts with Thymine, Adenine, and cytosine then the rest of the sequence is what makes each DNA different.

2. How does this activity help model the structure of DNA? What changes could me make to improve the accuracy?

This allows us to represent each part of the DNA strand using a physical object so we can clearly see where everything is placed. We could have differentiated with shapes rather than making the bases all the same. We also didn’t differentiate between 3 hydrogen bonds and 2, so that’s something we could have added.

1. When does DNA replication occur?

DNA replication occurs before cell division during the interface of mitosis after the check for size efficiency.

2. Names and describe the 3 steps involved in DNA replication. Why does the process occur differently on the leading and lagging strands?

First there is unwinding which is when the DNA unfolds and unzips when the two H bonds let go. Then there is the Complimentary base pairing step which is when nucleotides move into place and form H bonds with matching stand. Finally there is Joining where DNA ligase attaches to the lagging strand. A leading strand is the strand which is synthesized in the 5’-3’direction, whereas the legging strand is synthesized in the 3’-5’ direction.

3. 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 showed H bonds attaching to another H bond. And we showed the red Bigfoot candy as the DNA ligase going on the lagging strand as you can see in the picture. Then the watermelon candy represents DNA helicase breaking the H bonds and the blue big foot represents DNA polymerase which is H-bonding new nucleotides to the template strand. This activity clearly shows each step and each object involved in the replication. From the photo it is difficult to tell what the candies are and what they are doing, so I feel that we could’ve used other objects.