Chapter 4: Babies! (Comments due Wednesday 2/18)

How does a single cell develop into a multicellular organism with differentiated tissues? That's the topic of this chapter, which includes all sorts of pretty color plates to illustrate Carroll's points. Here are some questions you may want to address, in your consideration of this chapter:

• Before you read this chapter, how much had you thought about the processes involved in the development of an adult from an initial, single-celled zygote? How do your preconceived (ha! that's a double entendre) notions about embryonic development square with what you've learned in this chapter?
• Carroll analogizes the locations on a developing embryo to the geography of a globe of the earth. How well do you think this analogy holds up? In what ways are a spherical ball of cells (that will develop into an adult animal) similar to the spherical ball that is the earth?
• Observe Figure 4.5 on page 104. How do cells communicate to inhibit the expression of particular genes in adjacent cells? Can simple diffusion of signaling molecules explain butterfly wing patterns, for instance?

Please post your comments using the "Discuss" tag below no later than Wednesday, February 18.