All small GTPases of the Ras superfamily, Cdc42, Rac, and Rho act as molecular switches, inactive in the GDP-bound state and active in the GTP-bound state.

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#Unit 8. Inheritance Biology

In Paracentric inversion - a single crossover takes place in the inverted region an unusual structure results

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#Unit 8. Inheritance Biology

Dicentric bridge - Structure produced when the two centromeres of a dicentric chromatid are pulled toward opposite poles

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#Unit 8. Inheritance Biology

In paracentric inversion form,

Acentric chromatid - Chromatid that lacks a centromere

Dicentric chromatid - Chromatid that has two centromere

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#Unit 8. Inheritance Biology

Recombination is also reduced within a pericentric inversion. No dicentric bridges or acentric fragments are produced.

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#Unit 8. Inheritance Biology

Recombinant chromosomes have too many copies of some genes and no copies of others, so gametes that receive the recombinant chromosomes cannot produce viable progeny. 

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#Unit 8. Inheritance Biology

This suppression of recombination allows alleles adapted to a specific environment to remain together, unshuffled by recombinationsomes cannot produce viable progeny.