Single and double crossovers

[ratatat]

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Hi,

I looked at the Biological Sciences topic guide on the AAMC website and it included "single and double crossovers". I'm wondering what the basic requirement of knowledge is for those crossovers for the exam. Also, is it a high yield concept?

Thanks

 

[Compass]

Basically, know when they happen, why they happen, how they happen. Map distance I have never seen, but may appear. You might have to find out whether or not something has magically double-crossed over, for example in a pedigree.

 

[sv3]

Basically, know when they happen, why they happen, how they happen. Map distance I have never seen, but may appear. You might have to find out whether or not something has magically double-crossed over, for example in a pedigree.

any good resources? I have TPR and Ek and neither mention anything more than "single cross over". Seriously, they don't go into it. I am guessing single crossover is the transfer between two homologs but double could be 4? You could also interpret it as the number of genes crossing over buy i dont think that is correct.

hopefully someone can clear this up. I usually don't dwell on things that multiple sources don't cover though.

 

[ratatat]

http://en.wikipedia.org/wiki/File:Morgan_crossover_1.jpg
http://en.wikipedia.org/wiki/File:Morgan_crossover_2.jpg

I found those two images on wikipedia

 

[sv3]

http://en.wikipedia.org/wiki/File:Morgan_crossover_1.jpg
http://en.wikipedia.org/wiki/File:Morgan_crossover_2.jpg

I found those two images on wikipedia

thanks. Appears my "incorrect" guess was right and my likely correct guess was wrong....go figure. If these pics are right and I'm seeing it right, looks it single vs double is indicitive of the number of genes that are crossed over. I previously thought it meant number of chromos involved - which appears incorrect now. thanks for posting the links

 

[ratatat]

No problem man.