puffylover

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aamc 6, bs section, question 130

this passage suggests that the expression of disease genes probably is important in regulating normal cellular physiology because:

altered expression of disease gene leads to disease

how come the answer isn't:
the expression of the disease genes lead to disease


seems like genetics is a big topic on recent tests... anyone wanna reread the passage and explain it to me ;)
 

Geekchick921

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I have not taken AAMC #6, and probably will not, but are they talking about cancer? There are genes that are not cancer-causing in and of themselves, but if they mutate, the cell can start to grow into a tumor. They code for proteins that help regulate the rate of mitosis and differentiation, and when they malfunction, the cells just start running amok and can turn into a tumor cell. They're called proto-oncogenes, and they become oncogenes if they mutate.

There are also tumor suppressing genes that, as the name suggests, suppress the growth of tumors. They repair bad DNA, also control the rate of mitosis and can dictate apoptosis. If they malfunction, cancers can form this way as well.

Cancer.org has some good analogies for this about a car. but if this question isn't about cancer I think you can just forget everything I said. :)
 

RogueUnicorn

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the answer lies in this portion of the passage "Studies of DNA mutations in NF1 patients have revealed few mutations–too few to explain all the features of this genetically dominant disease."
 

RogueUnicorn

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let's try it another way, why do you think your answer is correct
 

sshah92

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I don't like this question either. First of all, it's badly written... no genes are "disease genes" because disease results from the altered expression of normal genes.

I chose B because the expression of disease genes, assuming disease genes exist, would result in disease -- and the altered expression (i.e. inactivation) of "disease" genes would eschew the disease from happening.
 

Arayh

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Well, I didn't read the passage, but altered expression of "disease" genes doesn't necessarily mean inactivation, but rather constitutively activated, and if this gene were a signal transduction protein for cellular proliferation, then you would satisfy one of the hallmarks for cancer.