Sanders 3rd EditionCh. 17 - Organelle Inheritance and the Evolution of Organelle GenomesProblem 23
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04:11In 1918, the Russian tsar Nicholas II was deposed, and he and his family were reportedly executed and buried in a shallow grave. During this chaotic time, rumors abounded that the youngest daughter, Anastasia, had escaped. In 1920, a woman in Germany claimed to be Anastasia. In 1979, remains were recovered for the tsar, his wife (the Tsarina Alexandra), and three of their children, but not Anastasia. How would you evaluate the claim of the woman in Germany?
The dodo bird (Raphus cucullatus) lived on the Mauritius Islands until the arrival of European sailors, who quickly hunted the large, placid, flightless bird to extinction. Rapid morphological evolution such as often accompanies island isolation had caused the bird's huge size and obscured its physical resemblance to any near relatives. However, sequencing of mitochondrial DNA from dodo bones reveals that they were pigeons, closely related to the Nicobar pigeon from other islands in the Indian Ocean. Why was mitochondrial DNA suited to the study of this extinct species?
Cytoplasmic male sterility (CMS) in plants has been exploited to produce hybrid seeds. Specific CMS alleles in the mitochondrial genome can be suppressed by specific dominant alleles in the nuclear genome, called Restorer of fertility alleles, RF. Consider the following cross:
♀CMS 1Rf 1/Rf1 rf2/rf2 × ♂CMS2rf 1/rf1 Rf2/Rf2
What genotypes and phenotypes do you expect in the F₁? If some of the F₁ plants are male fertile, what genotypes and phenotypes do you expect in the F₂?
Considering the phylogenetic assignment of Plasmodium falciparum, the malarial parasite, to the phylum Apicomplexa, what might you speculate as to whether the parasite is susceptible to aminoglycoside antibiotics?
Elysia chlorotica is a sea slug that acquires chloroplasts by consuming an algal food source, Vaucheria litorea. The ingested chloroplasts are sequestered in the sea slug's digestive epithelium, where they actively photosynthesize for months after ingestion. In the algae, the algal nuclear genome encodes more than 90% but not all of the proteins required for chloroplast metabolism. Thus it is suspected that the sea slug actively maintains ingested chloroplasts, supplying them with photosynthetic proteins encoded in the sea slug genome. How would you determine whether the sea slug has acquired photosynthetic genes by horizontal gene transfer from its algal food source? Discuss the steps required for heritable endosymbiosis to eventuate, and their plausibility.
Most large protein complexes in mitochondria and chloroplasts are composed both of proteins encoded in the organelle genome and proteins encoded in the nuclear genome. What complexities does this introduce for gene regulation (i.e., for ensuring that the appropriate relative numbers of the proteins in a complex are produced)?