BIOL Questions

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Use your knowledge of DNA replication to fill in the table below. Write a function in the first empty column. Use a check mark in the second and third to indicate whether the item from the first column is needed on the leading and/or lagging strand (also see the * note below the table). For the direction of DNA synthesis, circle “toward” or “away,” as appropriate.

	Purpose or Activity	Needed on Leading? *	Needed on Lagging? *
primase
helicase
ligase
dNTPs
topoisomerase
SSBs
Direction of DNA synthesis by DNA Pol. (DNAP)	(What is this direction?)	Toward or away from the replication fork?	Toward or away from the replication fork?
DNAPI
DNAPIII
RNA primer
DNA primer
Okazaki fragments

* Note that two of the enzymes work just ahead of and/or behind the replication fork, so are not directly associated with either the leading or lagging strand.

Complete the half-empty diagram on the next page, answering the questions that are asked below:

1. What region of the DNA helix is marked by the circled #1? This region of the DNA is opened by the __________ enzyme.

2. At the top of your diagram, indicate with arrows the different overall directions of replication fork movement. Is replication symmetrical or asymmetrical from the origin of replication?

3. In the space below, outline the steps involved in DNA replication.

4. In the diagram, you should recognize the replication fork to the left of the black line from the work we did in class. On your empty diagram (to the right of the black line) draw the process of replication for both strands of DNA for each step of DNA replication that you just outlined above.

a) include all of the enzymes and other components involved in DNA replication that we talked about in class.

b) indicate the polarity of the parent (old) and nascent (new) DNA strand (i.e. label each to indicate 5’ and 3’ ends)

c) indicate which strand is leading and which strand is lagging

5. What is the difference between replication on either side of the Origin of Replication? Is there a difference?