uncontrolled growth (tumor) question

[Meredith92]

This is a question from a tbr passage.

Mutated gene A has been shown to induce uncontrolled growth. in vivo studies of the gene have demonstrated normal levels of mRNA and protein product from gene A. From this info it can be concluded that:

A. the mutation in gene A has resulted in depressed RNA polymerase binding frequency
B. protein product A is necessary for entering mitosis
C. the mutation in gene A has resulted in a significant structural change in protein A
D. the cell line used posses a ******ed cellular ribosome level

C is correct. we know that gene A is known to induce cancer. also, form the info in the question we know there is nothing wrong with the transcription of the gene or efficiency of translating the messenger RNA. therefore we should conclude that even though the protein is synthesized, it is useless. recall that protein function is tied into its structure. therefore, a nonfunctional protein probably suffers from a significant change that resulted from the gene mutation


Okay, so I have a few difficulties with this question... when it says "mutated gene A" does it mean gene A normally is good and does not do uncontrolled growth... but when it is mutated it creates uncontrolled growth? OR does it mean that gene A is, itself, a mutated gene that results in uncontrolled growth. I chose B because i thought it meant a gene A is normally good, but its mutate form messes up growth... which implies it must have some effect on mitosis.

I'm not sure if my confusion is clearly explained... but if you can help me out that would be great. thanks so much

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[Trayshawn]

I believe the question meant to say "in vivo studies of the mutated gene..." as that would make everything make sense.

Gene A has a normal and mutated form. The normal form exhibits no such carcinogenic properties. The mutated form does. However, when studying that mutated gene in living organisms (aka in vivo), there is no issue with the making of mRNA or protein that gene A normally codes for. Thus, the issue is not likely with polymerase binding or ribosomes eliminating choice A and D. Choice B is a stretch and there is really no reason to suggest that it is necessary for entering mitosis. (It might have been a better answer if it said something like it being necessary to regulate mitosis since, when malfunctional, mitosis happens like crazy thus leading to cancer).

So the best answer is C. Something must just be wrong with the kind of protein produced.

 

[Meredith92]

Thank you! Just as a follow up question ( that may be a dumb question)- is cancer always related to problems w mitosis/ division?

 

[Deadlifts]

Thank you! Just as a follow up question ( that may be a dumb question)- is cancer always related to problems w mitosis/ division?

Cancers are unregulated cell growth so yes, mitosis is involved. Typically you have genes in place to regulate how fast mitosis occurs but mutations/etc. can change this (Oncogenes or tumor suppressors). Gene p53 is a good example of this.

That doesn't mean all cancers behave the same or have the same causal factors, though.