PDBIO Course

Discussion Board Due: A New Lifeform

The Purpose

I have found that students in my class often have difficulty understanding the Meselson Stahl experiment. The goal of this activity is to foster some virtual group study and discussion such that you achieve a deeper level of understanding. I give this same question to my face-to-face class, and find it is very beneficial for exam preparation.

The Instructions

• Review the slideshow DNA Replication associated with lesson 7, try to solve the problem at the end, and then share your thoughts with your classmates.
• My hope is that one or more of you will bravely post an answer from which others will either add to or modify. After sufficient discussion, I will join in and discuss the problem.
• To get credit for participation your contributions must be meaningful. For instance, "that's interesting" or "thanks for the information" does not count as participation.  Add your post, and then reply to/comment on a fellow student's post. As you use this discussion board, please be kind to each other.

The Problem: A New Life-Form

A new life-form is discovered on Mars. Scientists are thrilled to learn that it contains DNA. When scientists repeat the Meselson Stahl experiment on the Martian life-form, they get the results depicted below. What can you deduce from these data?