BIS 152 Homework 1

BIS 152 Homework 1 - Shivali Gupta September 8, 2009 BIS...

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Shivali Gupta September 8, 2009 BIS 152 Section 001 Maria Pallavicini T.A. Heather Bryan Homework 1 Chapter 2: #1, 5 Chapter 12: #3, 8, and 9 1. What types of observations allow a trained pathologist to identify the tissue of origin of a tumor? And why are certain tumors (5-10%) extremely difficult to assign to a specific tissue of origin? While tumor cells deviate substantially in behavior from their normal cellular precursors, they almost always retain some of the distinctive characteristics of the normal cell types from which they have arisen. These characteristics provide critical clues about the primary origins of most tumors. For example, an early indication of premalignant change in the esophagus is a metaplastic condition called Barrett’s esophagus , in which the normally present squamous epithelium is replaced by secretory epithelial cells of a type that is usually common in the stomach. Thus, such phenotypic characteristics aid in the identification of the preliminary origin of most tumor cells. In some situations, (5-10%), the tumors given to a trained pathologist are extremely difficult to assign to a specific tissue of origin, because these tumor cells have shed almost all of the tissue-specific, differentiated traits of their normal precursor tissues. Thus, such tumor cells are more commonly called dedifferentiated , and the tumors as a whole are called anaplastic , in other words that it is no longer possible for a pathologist to determine the origin of the tumor using histopathological criteria. 5. How can we estimate what percentage of cancers in a population that is avoidable (through virtuous
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This note was uploaded on 06/23/2010 for the course BIO 152 taught by Professor Ling during the Spring '10 term at UCM.

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BIS 152 Homework 1 - Shivali Gupta September 8, 2009 BIS...

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