homologous recombination molecular biology qustion

[biochem123]

I need help on this question for my test.

 

So in homologous recombination, you have 2 double stranded DNA in close proximity. Lets say the top chromosome has 5 repetitive sequences right after another, and the homologous chromosome below it has the same 5 sequences. These sequences are about 500 base pairs long. Let's say there is a DNA break on the third sequence set on the top strand. Then, homologous recombination, crossing over, non-crossovers, and other mechanisms will occur. Explain a reason that would result in overall 7 repeats of the sequence on the top strand and 5 still on the bottom strand.

 

Any help would be appreciated.

Thanks.

 

Here is a visualization

-------SeqSeqSe(DNA BREAK)qSeqSeq-----

 

-------SeqSeqSeqSeqSeq---------

[iRNAblogger]

So I don't think that you are supposed to get answers for test questions on this website (so I'm not sure if I'm "allowed" to answer this, so I will try to only nudge you in the right direction rather than give you a straightforward answer).

 

What would happen after the double-strand break? What's the next step? (I can tell you that it would be none of the mechanisms you mentioned) Think about the different DNA-repair pathways to answer the question of how double-strand breaks are resolved. What other approaches could you use that don't necessarily involve any of the mechanisms you mentioned? What other processes in the cell could lead to sequence repeat instability?

 

I have a possible answer in my head, but I'm not absolutely sure. Sorry for being so cryptic in my response!