Which of the following is NOT an organelle that is thought to be the result of endosymbiosis? A. mitochondrion B: chloroplast C.Golgi apparatus D.A & B
The Correct Answer and Explanation is:
The correct answer is C. Golgi apparatus.
Explanation:
Endosymbiosis is a scientific theory suggesting that certain organelles within eukaryotic cells, particularly mitochondria and chloroplasts, originated from free-living prokaryotic cells that were engulfed by an ancestral eukaryotic cell. Over time, these engulfed cells formed a symbiotic relationship with their host, eventually evolving into permanent, integrated organelles. The mitochondria are believed to have originated from a type of aerobic bacterium, while chloroplasts likely descended from photosynthetic bacteria (like cyanobacteria).
Now, let’s break down each option:
- Mitochondrion (A): Mitochondria are thought to have originated from ancient prokaryotic cells, specifically from an ancestor of aerobic bacteria. This is a clear example of endosymbiosis, as mitochondria have their own DNA, which is similar to bacterial DNA. They also replicate independently of the host cell’s replication cycle and have a double membrane, another indicator of their prokaryotic origins.
- Chloroplast (B): Chloroplasts, found in plant and algal cells, are similarly believed to have originated from cyanobacteria through an endosymbiotic event. Like mitochondria, chloroplasts have their own DNA and are involved in independent replication. They also have a double membrane structure, supporting the endosymbiosis theory.
- Golgi apparatus (C): The Golgi apparatus, on the other hand, is not thought to have originated through endosymbiosis. It is a membrane-bound organelle found in eukaryotic cells that is involved in processing and packaging proteins and lipids. Unlike mitochondria and chloroplasts, the Golgi apparatus does not have its own DNA, and its structure is derived from the endomembrane system of the cell, which is a feature unique to eukaryotes.
Therefore, C. Golgi apparatus is not an organelle believed to be the result of endosymbiosis.
