From an article cited in the OP [0], More than 95% of all proteins located in the mitochondrial compartments are encoded by the nuclear DNA, synthesized in cyt

From an article cited in the OP [0], More than 95% of all proteins located in the mitochondrial compartments are encoded by the nuclear DNA, synthesized in cytoplasmic ribosomes and imported into mitochondria. These include factors that regulate mitochondrial DNA (mtDNA) gene expression such as mtDNA and RNA polymerases, mitochondrial transcription factors, RNA processing and modifying enzymes, transcription termination factors, mitochondrial ribosomal proteins, aminoacyl-tRNA synthetases, and translation factors (1, 2). It's clear that a mitrochondrial element can't live for long without the presence of the host cells, so, like a virus, it doesn't meet all the requirements to be considered fully living. [0] https://pmc.ncbi.nlm.nih.gov/articles/PMC23071/ https://pmc.ncbi.nlm.nih.gov/articles/PMC23071/