Mitochondria evolved before chloroplasts based on which observation?Multiple ChoiceMitochondria produced the oxygen found in the atmosphere.Almost all organisms have mitochondria.All eukaryotes have mitochondria, but not chloroplasts.All prokaryotes have mitochondria, but not chloroplasts.Mitochondria are larger than chloroplasts.

Which of the following provides supporting evidence that mitochondria and chloroplasts may have once been free-living prokaryotes?ANSWERMitochondria and chloroplasts are relatively large organelles.Mitochondria and chloroplasts have similar function in that they are responsible for generating most of the cell’s ATP.Mitochondria and chloroplasts contain 70S ribosomes.Mitochondria and chloroplasts are non-membrane bound organelles.

There is evidence that eukaryotic cells evolved from a prokaryotic ancestor most closely related to the Archaea. What would you predict, regarding a comparison of the inner and outer chloroplast membranes, if the endosymbiotic theory of chloroplast evolution is true?

irst appeared during the Paleoproterozoic era, likely as flagellated cells. The prevailing evolutionary hypothesis is that they arose through symbiogenesis between an anaerobic Asgard archaean and an aerobic proteobacterium, leading to the formation of mitochondria. A subsequent symbiogenesis event with a cyanobacterium gave rise to plants, incorporating chloroplasts. Eukaryotic cells possess membrane-bound organelles like the nucleus, endoplasmic reticulum, and Golgi apparatus. Eukaryotes can exist as unicellular or multicellular organisms. In contrast, prokaryotes are typically unicellular. Unicellular eukaryotes are sometimes referred to

Which of the following is true of bothmitochondria and chloroplasts?(A) They are found in the cells of eukaryoticautotrophs and heterotrophs.(B) They include stacks of membranes thatabsorb light.(C) They include compartments where hydrogenions are concentrated.(D) They produce sugars using energy harvestedin the cytoplasm.(E) They break down sugar to produce ATP

Eukaryotic organelles such as mitochondria and chloroplasts are believed to be relics of formerly free-living prokaryotes.  The transition from a hypoxic (low O2) to an oxic atmosphere (21% O2) is said to have enabled primitive eukaryotic anaerobes to engulf ancient aerobic prokaryotes and consequently acquire the ability to produce energy through oxidative phosphorylation.  This endosymbiotic theory of eukaryotic evolution also postulates that endosymbiosis resulted in larger eukaryotic genomes, which originated from the partial transfer of mitochondrial genes to the nuclear genome.  On integration into the host genome, mitochondria-derived genes became indistinguishable from the original nuclear genes.Researchers have alternatively proposed that after a prolonged period of symbiosis, the possibility exists of gene transfer from eukaryotes to prokaryotes.  This hypothesis was initially supported when copper/zinc (Cu/Zn) superoxide dismutase (SOD), a metalloprotein confined to the cytosol of eukaryotic cells, was found in Photobacterium leiognathi.  The free-living bacterium P. leiognathi is also a known symbiont of ponyfish, a small fish species native to the Indian and Pacific Oceans.SODs are antioxidant enzymes that serve as the cell's first line of defense against reactive oxygen species (ROS).  ROS produced by the electron transport chain damage proteins by oxidizing amino acid residues and metal ions on prosthetic groups but can accumulate during times of biochemical and environmental stress.  Superoxide (O2−) radicals, a form of ROS, are sequestered by SODs and converted into less toxic hydrogen peroxide (H2O2) and O2 gas.Adapted from Bannister, J.V., & Parker, M.W. (1985). The presence of a copper/zinc superoxide dismutase in the bacterium Photobacterium leiognathi: a likely case of gene transfer from eukaryotes to prokaryotes. Proceedings of the National Academy of Sciences of the United States of America, 82(1), 149–152. Question 22Ponyfish cells containing P. leiognathi symbionts were exposed to a spindle fiber toxin that specifically inhibits microtubule polymerization.  Given this information, which of the following would most likely result as a consequence of toxin exposure?A.P. leiognathi daughter cells with multiple copies of the Cu/Zn SOD geneB.Ponyfish daughter cells containing the same copy number of the Cu/Zn SOD geneC.Delayed separation of P. leiognathi cells during binary fissionD.Nondisjunction in somatic ponyfish cells undergoing nuclear division