Answer:
Eukaryotes are hypothesized to have evolved from prokaryotes, as supported by the endosymbiotic theory where mitochondria and chloroplasts in eukaryotic cells share significant similarities with prokaryotic cells. This includes similar DNA, membrane structures, division processes, and ribosomes. Fossil records and modern DNA analysis corroborate the evolutionary link between these two domains.
Step-by-step explanation:
Evidence of Eukaryotic Evolution from Prokaryotes
The concept that eukaryotes evolved from prokaryotic organisms is backed by various structural and genetic pieces of evidence. One of the central pieces of evidence is the endosymbiotic theory, which posits that key eukaryotic organelles, namely mitochondria and chloroplasts, originated from free-living prokaryotes that were engulfed by ancient ancestral eukaryotic cells.
Both mitochondria and chloroplasts have similarities with prokaryotic cells that support this theory. They contain their own circular DNA, which is akin to prokaryotic DNA, and have a double-membrane structure where the inner membrane is thought to be the original prokaryotic cell's membrane. Additionally, the way these organelles divide is reminiscent of bacterial binary fission, and their ribosomes are more similar in size and structure to prokaryotic ribosomes than to those typically found in eukaryotic cells.
The appearance of fossils also supports the evolutionary lineage from prokaryotes to eukaryotes. Fossils dating back to around 3.5 to 3.8 billion years ago show structures associated with bacteria, such as cyanobacteria, while eukaryotic fossils appear in the record at about 2 billion years old. Furthermore, modern DNA analysis reveals that some eukaryotic genes show homology with bacterial DNA, which points to the mixed heritage from both the Archaea and Bacteria domains, further supporting the hypothesis of endosymbiotic events being a significant factor in the evolution of eukaryotic cells.