DNA is a large polymer that is made up of multiple nucleotide monomers. Nucleotides are made up of 3 different components which include a sugar, a phosphate group and a nitrogenous base. It contains 2 backbones that are made up of bonded sugar-phosphate portions of adjacent nucleotides. The two complimentary strands that DNA is made up of, run antiparallel to each other which means they run opposite directions. Each strand has a 5’ end and a 3’ end. The two strands being antiparallel means that complementary base pairing can happen which allows the two DNA strands to be held together. Bases always bond with the same partner (Adenine and Thymine, Guanine and Cytosine)
This activity helped model the structure of DNA because it showed how complementary base pairing works and how new strands of DNA can form. It also helped to show the shape of DNA. To help improve the accuracy of the model we could have used different objects to help show different bonds and where they happen.
DNA replication is an essential part of cell division and the growth of all organisms. It uses strands of DNA to create new strands. It occurs before new cells are formed because it requires genetic information for it to split.
The 3 steps that are involved in DNA replication are: Unwinding, complementary base pairing, and joining. Unwinding is when the DNA helix unwinds and the H-bonds between base pairs break. The DNA helicase enzyme is what causes DNA to unwind. Complementary base pairing is when nucleotides move into place to form and H-bond with their “partner” on another strand. Polymerase is what causes complementary base pairing. Joining is when nucleotides on a new strand form covalent bonds with their “partner”. The leading strand is continuous as DNA continues to unzip and the lagging strand has fragments form as DNA unzips. DNA ligase is what glues fragments together. A leading strand is synthesized in the 5’ to 3’ direction while a lagging strand is synthesized in the 3’ to 5’ direction.
To model the complementary base pairing, we detached some of the pairings from each other and then used different coloured playdough to show what helicase, polymerase, and ligase do. The model was helpful in showing what the different enzymes did, but it was not helpful in the way that our model kept falling apart and sometimes the instructions were not clear so we didn’t know what we were supposed to do some of the time.
