Biology 120                                Handout: Organogenesis and Cancer                                       R. Irwin

Organogenesis: specialization of different tissues for different functions

Cancer:


Evolution of cancerous cells:

              o cells with more cancerous mutations reproduce faster
              o over time, most cells in a tumor are cancerous
              o this is natural selection occurring among cells
              o result: increased malignancy over time because cells with most cancerous mutations are most malignant


 QUESTIONS:

1.   Give examples of human tissues derived from ectoderm, endoderm, and mesoderm
2.   Given that virtually all body cells have the same genes in them, and genes are what code for the appearance & biochemistry of cells, how is it possible for cells to have different structure and different biochemistry from each other?
3.   How do rates of cell division and cell growth change through the process of embryogeny?
4.   What determines what kind of cell a particular cell produced during development specializes into?  What experiments have demonstrated this process?
5.   The two main features of cancer are growth of large balls of undifferentiated cells called _________________ and the fact that cells from these tumors spread through out the body through the process called _____________________.
6.   Are all tumors cancerous? Explain.
7.  Tumors are made of:
  a. bacteria that have infected the body
  b. an individual's own body cells that have mutated to grow uncontrollably
  c. an individual's own body cells, but ONLY if that individual has been infected by a tumor-causing virus
  d. an individual's own body cells, but ONLY if that individual has been infected by tumor-causing bacteria
8.  What are the two main ways cancer is treated?  Why do these cancer treatments have such extreme side effects?
9.  What is the difference between a benign tumor and a malignant tumor?  Some tumors start out benign and become malignant.  How is this related to the clonal evolution theory?  How can this help with cancer prevention?
10.   Many genetic traits you have learned about are either present or not present (e.g. you either have blue eyes or you don't), but with regard to cancer very few cancers are coded that directly -- instead, people have predispositions to cancers but may or may not actually get them.  Why is this?
11.  How is cancer related to the process of embryogeny?  What is similar in terms of structure and in terms of genetics between the development of an embryo and the development of a tumor?
12.  Why do we have genes that when either activated or suppressed result in cancers?  What necessarily roles do such genes play (so that we can't get rid of these genes)?
13.  The two kinds of normal gene in our body that, if they mutate, can result in cancer are called _________________ and _______________________.  How does each of these genes function normally?  How can mutations in such genes cause cancer?

 HOMEWORK QUESTIONS FROM THE REUTERS PAPER:

1.  What is angiogenesis?  How can understanding angiogenesis potentially be used to treat cancer (what would be done to tumors to help get rid of them based on a knowledge of angiogenesis)?  Briefly, how is the science of genomics being used to help develop such treatments (treatments based on knowledge of angiogenesis.)

2.  How do the blood vessels in tumors differ structurally (that is, in terms of the physical structure, not genes, of the blood vessels) from normal blood vessels?  How do blood vessels in tumors and blood normal blood vessels differ in gene expression? Relate this to the material from lecture by explaining whether the pattern of gene expression suggests that the genes involved are oncogenes, tumor suppressor genes, or some of both.  Justify this last point based on the stated ways in which the genes in normal and tumor blood vessels differ, and on an explanation of what oncogenes and tumor suppressor genes are.