Which of the following structures are believed to have originated through endosymbiosis according to the endosymbiotic theory?

• A. Endoplasmic reticulum and peroxisomes
• B. Nucleus and ribosomes
• C. Mitochondria and chloroplasts
• D. Golgi apparatus and lysosomes

Answer: (C)

Verified step by step guidance

1. Understand the endosymbiotic theory: This theory suggests that certain organelles in eukaryotic cells originated from free-living prokaryotic cells that were engulfed by an ancestral eukaryotic cell. These prokaryotes formed a symbiotic relationship with the host cell, eventually evolving into organelles.
2. Identify the key organelles associated with the endosymbiotic theory: Mitochondria and chloroplasts are the primary organelles believed to have originated through this process. They share similarities with prokaryotes, such as having their own DNA, double membranes, and the ability to replicate independently of the host cell.
3. Eliminate incorrect options: The endoplasmic reticulum, peroxisomes, nucleus, ribosomes, Golgi apparatus, and lysosomes are not believed to have originated through endosymbiosis. These structures are either formed by the host cell itself or have different evolutionary origins.
4. Focus on the correct answer: Mitochondria and chloroplasts are the correct answer because they exhibit characteristics that strongly support their prokaryotic ancestry, such as circular DNA and ribosomes similar to those of bacteria.
5. Conclude with the reasoning: The endosymbiotic theory is supported by evidence such as the genetic and structural similarities between mitochondria, chloroplasts, and prokaryotes, making them the most likely candidates for having originated through endosymbiosis.