- Explain the structure of DNA – use the terms nucleotides, antiparallel strand, and complimentary base pairing.
DNA is also called Deoxyribonucleic acid, it is mand out of sugars, phosphates and nitrogen bases. DNA is a large polymer made of nucleotide monomers that have 2 backbones, which formed by bonded sugar-phosphate portions of adjacent nucleotides. The two strands are antiparallel, one strand will start with sugar, then phosphate, then sugar, the other strand is opposite that start with phosphate, then sugar. Between the two strands, there are many nucleotide bases that make ladders, H-bonds link between base pairs to form complimentary base pairing that made by Pourine and Pyramidine, which are Adenine and Thymine, Guanine and Cytosine.
- How does this activity help model the structure of DNA? What changes could we make to improve the accuracy of this model? Be detailed and constructive.
By modeling the structure of DNA, we can have a better visual of hoe DNA is look like and by the time we making it, we can be much clearer about the details that we might not know by just reading. For example, when the time me and my groupmates make the DNA, I truly understand how antiparallel strand means, the pink beads that represent the phosphate should be at opposite direction.
To make the model more accurate, we can change the material that we use, maybe use other things to represent the H-bonds that we need to cut ourselves that is hard to keep them same and also when we try to link to strands together, it is easy for them to came apart, especially when it is winding.
- When does DNA replication occur?
DNA replication occurs before cells divide, it replicates to double cell structures and their genetic information.
- Name and describe the 3 steps involved in DNA replication. Why does the process occur differently on the “leading” and “lagging” strands?
The three steps involved in DNA replication are unwinding and unzipping, complimentary base pairing and joining. For the first step – unwinding and unzipping, the helix unwinds and unzip, H-bonds between the base pair break. It is caused by DNA helicase. Then the complimentary base pairing is involved by DNA polymerase, which is the new strand will be pairing with the leading strand to form base-pairs that sill A to T and C to G. The last step is Joining, DNA ligase glues the new strands to the leading strand that make a new DNA. Leading strand and lagging strand are different because leading strand continuous as DNA unzips, but the lagging strand is fragments form as DNA unzips DNA ligase glues fragment.
DNA helicase unzip DNA
complimentary base pairing
DNA ligase join the adjacent nucleotides
DNA replication finished (get two DNA)
- 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 use different colour beads to show how the base pair is on the pipe cleaners, twist the white pipe cleaners to join them together. The model we make this time give us a feel of how DNA replicates and how enzymes works in the process, but it is more focus on the leading strand that we didn’t really look at lagging strand and shows how it works in the DNA replication.