question on paracentric inversion

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Zeph - 22 Sep 2006 04:09 GMT

I'm looking at paracentric inversion when crossing over occurs. Is the
final result four gametes, but only two of the gametes have the proper
number of genes? One gamete has the normal chromosome, one has the
chromosome with the inversion, and the other two have the fragmented
chromosome piece (not the acentric piece). I was watching an animation
and this is what I have concluded.

Thanks.

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Bob - 23 Sep 2006 02:32 GMT

>I'm looking at paracentric inversion when crossing over occurs. Is the
>final result four gametes, but only two of the gametes have the proper
>number of genes? One gamete has the normal chromosome, one has the
>chromosome with the inversion, and the other two have the fragmented
>chromosome piece (not the acentric piece). I was watching an animation
>and this is what I have concluded.

Well, let's see if we can figure out what you are asking. I suspect
you intended to ask about a meiotic event involving a normal
chromosome and one carrying the inversion -- though you seem to say
you are asking about making an inversion. And if you are asking about
crossing over, we need to specify the region of the crossover. The
question is only interesting if the crossover of concern is in the
inverted region.

Yes, only two "normal" gametes are produced -- those not affected by
such a crossover. Of course, that is making a simplifying assumption
-- that there is only one crossover. Getting any good gametes requires
that there be no crossovers within the inverted region.

Now, what happens in a crossover within the inverted region? One
dicentric and one acentric chromosome. Yes?

bob

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Natural Science Forum / Biology / Microbiology / September 2006

question on paracentric inversion