READ: Background DNA replication is the process whereby the cell makes an identical copy of the whole genome (all the DNA inside the cell) in preparation for cell division. It involves a number of steps that are catalyzed and coordinated by a number of different proteins. To prepare for this lab, you are going to work through a computer simulation of the process and answer some questions about it. Then you will model the process of DNA replication using paper DNA and proteins.
HW Assignment
❖ Go to the following website: http://www.phschool.com/science/biology_place/biocoach/dnarep/intro.html
● A google search for “DNA Replication phschool” might be easier than typing in the URL. It should be the first hit.
● CLICK on Concept 4: Biosynthesis of DNA (in the panel on the left side of the screen). Then click on the purple “Review” button.
- In which direction does the DNA polymerase move?
- What is the substrate for DNA polymerase?
- How does DNA polymerase know which base to add to the growing chain?
- What type of bond is formed between the growing DNA chain and the new nucleotide?
● Click on “Concept 5: Replicating Antiparallel DNA Strands” then on the “Review” button in the upper right corner of the screen. Watch the 5 steps of DNA replication and answer the following questions:
- In an unlabeled diagram, how can you identify the leading strand?
- In an unlabeled diagram, how you can identify the lagging strand?
- Why are there Okazaki fragments in the lagging strand but not the leading strand?
- What nucleic acid polymer is created first on the lagging strands? Should there also be this polymer in the leading strand?
- Why is it necessary to have an RNA primer before DNA is produced?
- What does DNA Polymerase I do? Why is this important?
- What does DNA ligase do? What would happen if there wasn’t DNA ligase around during DNA replication?
- Why does the animation call DNA replication “semi-continuous”?