Basic meiosis question

[dae]

In metaphase I can both of the chromatids of a double chromosome crossover? In textbooks the tetrad complex is always shown laid flat (it looks like XX ) so it makes since that only one chromatid from each double chromosome would be able to recombine in that geometry. But if this is a simplification for the sake of 2D display and the tetrad complex can actually assemble so that one double chromosome lays on top of the other (I can think of any reason they couldn't) than it makes sense that both chromatids could cross over.

Does anyone know the actual geometry of metaphase I?

Thanks!

[plasmodesmata11]

The chromosomes do synapse as if the X's were on top of each other. I guess in your book the diagrams are simplified.

[MrMistery]

during a crossover 2,3 or 4 strands can cross over.
See the figures in this book http://books.google.com/books?id=3E_0H6 ... #PPA193,M1

[dae]

Thanks! that makes way more sense