Chapter 20

Distinguish among totipotent, pluripotent, and multipotent stem cells, and give an example of where you would find each type of cell.

Explain how an individual's own cells might be used in stem cell therapy.

Draw a diagram to illustrate how a concentration gradient of a transcription factor along the anterior-posterior axis of a Drosophila embryo can create a region in the middle in which transcription of a target gene takes place without being transcribed in either the anterior or posterior region.

Expression of a homeotic gene in the wrong tissue in Drosophila results in the development of an inappropriate body part from that tissue. Explain why this happens and how it shows that homeotic genes are positive regulators of developmental pathways.

Explain why master regulatory genes tend to be more strongly conserved in evolution than are the downstream genes they regulate.