Challenge Questions

Section 21.3

Question 21.34

Would the genomic conflict hypothesis likely explain genomic imprinting for genes involved in adult memory? Why or why not?

Question 21.35

In recent years, techniques have been developed to clone mammals through a process called nuclear transfer, in which the nucleus of a somatic cell is transferred to an egg cell from which the nuclear material has been removed (see Chapter 22). Research has demonstrated that when a nucleus from a differentiated somatic cell is transferred to an egg cell only a small percent of the resulting embryos complete development and many of those that do die shortly after birth. In contrast, when a nucleus from an undifferentiated embryonic stem cell is transferred into an egg cell, the percentage of embryos that complete development is significantly higher (W. M. Rideout, K. Eggan, and R. Jaenisch. 2001. Science 293:1095–1098). Propose a possible reason for why successful development of cloned embryos is higher when the nucleus transferred comes from an undifferentiated embryonic stem cell.

Section 21.4

Question 21.36

The use of embryonic stem cells has been proposed for replacing cells that are destroyed by disease or injury. Because of ethical concerns about creating and destroying embryos to produce embryonic stem cells, researchers have attempted to create induced pluripotent cells (iPSCs). In this chapter we discussed studies showing that iPSCs retain some epigenetic marks of the differentiated adult cells from which they were derived. What implications might this research have for attempts to use iPSCs to regrow cells and tissue?

Go to your to find additional learning resources and the Suggested Readings for this chapter.