Given the Putative Ancestry of Giardia's Mitosome, What Should We

Question

Given the putative ancestry of Giardia's mitosome, what should we predict is true of the mitosome?
A) It has electron transport systems that use oxygen as the final electron acceptor.
B) It has a double membrane.
C) It has thylakoids.
D) It contains microtubules, arranged in the "9 + 2 pattern."
E) It contains 80S (eukaryotic) ribosomes.

Accepted Answer

The mitosome is thought to have originated from the mitochondria-like organelles of an ancestor of Giardia that had a double membrane. Therefore, we can predict that the mitosome also has a double membrane.

Answer: E
 The mitosome is thought to have lost most of the genes necessary for oxidative phosphorylation and energy production. Therefore, it likely lacks electron transport systems and 80S ribosomes. However, it likely retains some eukaryotic-like features, such as 80S ribosomes, that were present in its ancestor's mitochondria-like organelles.