Mitochondria and chloroplast are considered to be endosymbionts of cells because they

Options

A. Possess their own nucleic acid
B. Have capacity of ATP synthesis
C. Do not reproduce
D. All the above

Answer

**Step-by-Step Solution:**

1. **Definition of Endosymbionts**: Begin by understanding what an endosymbiont is. An endosymbiont refers to an organism that lives within the body or cells of another organism in a mutually beneficial relationship.

2. **Origin of Mitochondria and Chloroplasts**: Historically, mitochondria and chloroplasts are believed to have originated from free-living prokaryotic cells. These prokaryotes were engulfed by ancestral eukaryotic cells through a process called endocytosis.

3. **Characteristics of Mitochondria and Chloroplasts**: Both mitochondria and chloroplasts possess their own circular DNA, similar to that of prokaryotes. This DNA is distinct from the nuclear DNA found in eukaryotic cells.

4. **ATP Synthesis**: Mitochondria are known as the powerhouse of the cell because they generate ATP through cellular respiration. Similarly, chloroplasts are involved in photosynthesis, converting light energy into chemical energy.

5. **Reproduction**: Unlike typical organelles that replicate during cell division, mitochondria and chloroplasts do not reproduce independently. Instead, they are replicated when the eukaryotic cell divides.

6. **Conclusion**: Because of their unique characteristics—having their own DNA, the ability to synthesize ATP, and their method of reproduction—mitochondria and chloroplasts are considered endosymbionts of eukaryotic cells.

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