Answer:
Yes. A eukaryotic organisms have mitochondria or some degenerate form of mitochondria. Monocercomonoides is an unusual organisms that does not have the slightest indication that it has a mitochondria nor have at least an abbreviated form of mitochondrial proteins. However, scientist conclude that mitochondria must have once been present in this organism and later lost them.
Explanation:
Usually a eukaryote has some genes in their nuclear DNA needed to assemble mitochondria but that genes were not present in Monocercomonoides. It also does not have a genes for making the energy extracting enzymes. Thus this extraordinary organism refuses to adhere to the basic requirement of a eukaryotes.
However scientist classify Monocercomonoides to be a eukaryotes though it does not show evidence of having a mitochondria simply because it is now commonly accepted that mitochondrion-related organelles (MROs) are essential composition in all newly discovered eukaryotes and that mitochondrial endosymbiosis takes place before radiation of all extant eukaryotes. It means that evolutionist assume that the mitochondria evolved in the common ancestor of all eukaryotes and conclude that mitochondria must have once been present in this organism and later lost them.
Monocercomonoides can still carry out all of its basic functions of life by obtaining energy from glucose using anaerobic metabolic pathways that operates in the cytoplasm of its cell. They utilize glycolysis, the same non-oxygen-requiring,energy-generating biochemical pathway found in the cytoplasm of all cells to metabolize glucose. It gets more energy by using a series of enzymes that breaks down arginine, an amino acid.
The organism could be considered a life form because evolutionist believed that it started out its existence with mitochondria, received a genes for iron-sulfur cluster synthesis from bacteria and lost its mitochondria. With their strange ways to energize their life and build structures for survival, Monocercomonoides live inside a mammalian intestine, a low oxygen environment.
This protist is a remarkable organism that surprises scientist and pushes the limits of what is actually known in biology.