Wrapping Up DNA Replication

To start class today I gave students a chance at some extra credit on Monday's test.  Each student was given a set of 15 pictures to first separate into mitosis and meiosis and then put in order.  See me as soon as possible if you were absent for this opportunity!

We finished our discussion of DNA replication by discussing how errors are minimized.  This is addressed on p. 305 of your textbook.  Next we talked about why the ends of chromosomes shorten with each replication.  The process is summarized on p. 306.  Our conversation extended to the ethical implications of using telomerase as a treatment for disease and/or aging.  It is an interesting area to think about and one that we will likely be hearing more about in the next decade!

Toward the end of class I shared an AP Free Response question on the topic of DNA structure and replication.  The question is below:

Scientists seeking to determine which molecule is responsible for the transmission of characteristics from one generation to the next knew that the molecule must (1) copy itself precisely, (2) be stable but able to be changed, and (3) be complex enough to determine the organism's phenotype.

• Explain how DNA meets each of the three criteria stated above.
• Select one of the criteria and describe experimental evidence used to determine that DNA is the hereditary material.