AP BIOLOGY

Detailed explanation-1: -Mitochondria and chloroplasts likely evolved from engulfed prokaryotes that once lived as independent organisms. At some point, a eukaryotic cell engulfed an aerobic prokaryote, which then formed an endosymbiotic relationship with the host eukaryote, gradually developing into a mitochondrion.

Detailed explanation-2: -The first endosymbiotic event occurred when a eukaryotic cell engulfed a prokaryote (SF Fig. 2.4 Step 3). This process, known as primary endosymbiosis, created the mitochondrion. Chloroplasts likely evolved when a eukaryotic cell containing mitochondria engulfed a photosynthetic cyanobacteria cell (SF Fig.

Detailed explanation-3: -It has now been firmly established that mitochondria and plastids, the classical membrane-bound organelles of eukaryotic cells, evolved from bacteria by endosymbiosis.

Detailed explanation-4: -Endosymbiotic theory goes back over 100 years. It explains the similarity of chloroplasts and mitochondria to free-living prokaryotes by suggesting that the organelles arose from prokaryotes through (endo)symbiosis.

Detailed explanation-5: -Mitochondria arose through a fateful endosymbiosis more than 1.45 billion years ago.