Prophase I of meiosis
Name: Marv J Mikesh
How do homologous chromosome pairs cross-over during prophase I of meiosis?
As the chromosomes begin to prepare for meiosis, they go through duplication,
just as in mitosis. Except, during prophase I, all 4 strands of one homologous pair
segregate together. These four strands are "stuck together" like four pieces of
spaghetti. This is called synapsis, and the four strands together are called a tetrad.
In this "twisted" condition, it is possible for adjacent strands to break and exchange
homologous segments - this is crossing over. Is this detailed enough, or do you need
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Update: June 2012