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This interrupted case study examines molecular genetic evidence reported in scientific literature to determine the fate of Louis-Charles, son of Louis XVI and Marie-Antoinette of France. Controversy and rumors surrounding the death of Louis-Charles suggested that either he died as a young boy while being held in captivity by the French revolutionaries or he escaped and was replaced by a substitute who died in his place. One individual claiming to be Louis-Charles was Karl Naundorff. Students begin the case by preparing pedigrees for the descendants of Maria Theresa and Francis I, the Holy Roman Emperor, parents of Marie-Antoinette. The pedigrees can be used to introduce the concepts of alleles identical-by-descent and cytoplasmic inheritance patterns. Students then compare mitochondrial DNA sequences and XY chromosome sequences from hair, bone, heart, and blood samples taken from descendants of Marie Theresa, Karl Naundorff and the heart of the boy who died in captivity to determine if the latter was truly Louis-Charles. An optional PowerPoint presentation with clicker questions is available to help guide the classroom activities.

There are a significant number of genetics curriculum resources designed by different companies, curriculum development outlets, state curriculum designers and individual teachers. What resources are good? How do you know? As part of the Geneticist-Educator Network of Alliances (GENA) Project, a Curriculum Content Review Committee was formed to review readily available classroom resources about patterns of inheritance. Click here to see original evaluation form used by the committee and here to see the summary of the committee's review.

The Y chromosome is only one-third the size of the X. Although the Y has a partner in X, only the tips of these chromosomes are able to recombine. Thus, most of the Y chromosome is inherited from father to son in a pattern resembling asexual, not sexual, reproduction. No recombination means no reassortment, so deleterious mutations have no opportunity to be independently selected against. The Y chromosome therefore tends to accumulate changes and deletions faster than the X. Degradation doesn't occur in X chromosomes because during female meiosis, the X has the other X as a full partner in recombination.

Variety of lesson resources