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Modern Genetic Analysis Answers to Selected Problems
Chapter 15*

3.

a. This would be dominant. The misexpression of FasL from one allele would be dominant to the normal expression of the wild-type FasL allele. In this case, each liver cell would signal its neighboring cells to undergo apoptosis.
b. No. It would lead to excess cell death, not proliferation.
See question

4.

(1)Certain cancers are inherited as highly penetrant simple Mendelian traits.

(2)Most carcinogenic agents are also mutagenic.

(3)Various oncogenes have been isolated from tumor viruses.

(4)A number of genes that lead to the susceptibility of particular types of cancer have been mapped, isolated, and studied.

(5)Dominant oncogenes have been isolated from tumor cells.

(6)Certain cancers are highly correlated to specific chromosomal rearrangements.

See question

6. | Inhibition of apoptosis can contribute to tumor formation by allowing cells to have an unusually long lifetime in which to accumulate various mutations that lead to cancer. Additionally, the normal role of apoptosis in removing abnormal cells and, through p53, killing cells that have "damaged" DNA also would be inhibited. See question

9. | p53 detects and is activated by DNA damage. When activated, p53 activates p21, an inhibitor of the cyclinCDK complex necessary for the progression of the cell cycle. If the DNA damage is repairable, this system will eventually deactivate p53 and allow cell division. However, if the damage is irreparable, p53 will stay active and will activate the apoptosis pathway, ultimately leading to cell death. For this reason, the "loss" of p53 is often associated with cancer. See question

© 1999 by W. H. Freeman and Company. All rights reserved.