More questions
posted by pam39 at 10:02 AM
Tuesday, July 17, 2007
BIOL335 links
- Your textbook!
- UBC BIOL335 website(updated)
- More than you'll need to know on P elements
- Link to a site on Ac/Ds elements
- Landmark discoveries in molecular biology
- Link to mol.gen. of prokaryotes course at univ. of Arizona
- Lac operon stuff
- Link to a clatech problem set
- Link to another caltech problem set
- Link to Dr. Zimmerman's molbiol-check out their links!
- BIOL334 website
Genetics links
- Your textbook!
- Traditional genetics terms
- Human genetics problem sets (University of Arizona)
- Mixed problem set
- Another problem set (vcu)
- Another problem set (vcu)
- Pam's loppins questions
- Triploid bananas: how does it work?
- BIOL334 website
Previous Posts
- On RFLPs, chromosome walking, etc!
- More questions
- markers question
- extra help session
- post-midterm thoughts
- A few answers
- QUESTIONS THAT CAME UP!
- TECHNIQUUES
- ANNOUNCEMENT
- SOME QUESTIONS THAT CAME UP
7 Comments:
Pam, are you going to post the VNTR question with the 2 senarios? I didn't understand it too well maybe you can give a briefing of it.
Thank you so much :)
So, with AC type we can jump out at anytime, but with the P-element it has to be present in the mother and then we would not see any eyelashes???
With Ac-type elements, there's no repressor to worry about, and it can jump in any cell.
So the mother (found under the car) could be e-/e[Ac] or homozygous for e[Ac], and just by chance, in her own cells, the TE did not jump out in any of the cells around her eyes. However, it might have jumped out in some other cells (that don't make eyelashes anyway, so the "patchy" phenotype is not visible)...
The patchiness of the offspring would be due to some jumping in somatic cells...
If something noramlly represses, then a GOF means that it will repress even better and a LOF would be that it does not repress anymore?
So, for proto-oncogenes when they GOF they will run thru the cell cycle even faster (increasing it's normal functioning), but it will never go thru a LOF because if it does the cell will die and they are more often dominant?
For tumor-supressors we have a LOF because it's mostly found in recessive state. Thus if we have a LOF here, we will end up waiting a long time to go thru the cell cyecle because we will be "paranoid"?
As you can see Pam I need help with this concept
Yes, if the function of something is to repress, a GOF mutation will make it repress even better, or repress at times/in places where it usually isn't in action. And yes, a LOF would cause "it" not to repress anymore (or to repress less efficiently).
Proto-oncogenes can actually have LOF mutations, but this type of mutations usually have little effect. First of all, LOF mutations are more often recessive, so you'd need both copies of the genes mutated in the same cell. Then, as you said, LOF mutations in proto-oncogenes will put the cell at a huge disadvantage (they may make the cell 'get stuck' at some point in the cell cycle, or die when it's not supposed to), so either nothing happens, or the cell dies--> no direct visible effect.
For tumor suppressor genes it's the opposite. Since these genes are usually involved in "double checking", fixing, doing quality control, slowing down the process, etc, we will most likely see the effect of mutations that are LOFs.
For example, if you have a LOF for a gene that usually monitors DNA for mistakes, then the cell will become sloppy and won't care about problems in the DNA (base pair mismatches, lesions in the DNA, etc). This will cause the cell to keep going through the cell cycle even though there are problems in the DNA, so over time it will accumulate many mutations-a recipe for disaster!
LOFs are usually recessive, so you will need both copies of your tumor suppressor gene of choice mutated in the same cell in order to see an effect.
On the other hand, if we had a GOF in our gene involved in DNA "quality control", the cell will become "paranoid" and will keep checking its DNA over and over. This may slow down the cell cycle and put the cell at a disadvantage (it won't grow and divide as fast as the WT cells), so either we'll see no noticeable effect, or the cell will die (and again, nothing really noticeable-it's just ONE cell).
In summary:
LOFs in proto-oncogenes and GOFs in tumor suppressor genes--> not much of an effect, and typically nothing "nasty"
GOFs in proto-oncogenes or LOFs in both copies of a tumor suppressor gene--> the cell becomes more susceptible to become cancerous.
Cheers!
Pam
OMG thnx so much PAM, I was not able to sleep all night thinking about this concept.
Will we be having a review on thursday, like tying up all the lose ends?
basically, with the GOF in proto-oncogenes the cell will become hyperactive (more cells produced) and a LOF in tumor supressor genes the cells become sloppy (more cells go thru the cell cycle missing check points and leaving with multiple mistakes.
So, together they will cause cancer because there is an increase in the number of cells with an increase in the number of mistakes
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