Cell Organelles with Their Own DNA

Cell organelles having their own DNA are:

Correct Answer: Both Mitochondria and Chloroplast

Both mitochondria and chloroplasts contain their own circular DNA (similar to prokaryotic DNA), their own ribosomes (70S), and can replicate semi-autonomously within cells. This is explained by the endosymbiotic theory (Lynn Margulis).

Endosymbiotic Theory

Mitochondria evolved from aerobic bacteria and chloroplasts from cyanobacteria, engulfed by ancestral eukaryotic cells in an endosymbiotic relationship. Over billions of years, most of their genes transferred to the nucleus, but they retained some.

Key Features of Mitochondria

• Double membrane-bound organelle.
• 'Powerhouse of the cell' — site of oxidative phosphorylation and ATP production.
• Contains circular mitochondrial DNA (mtDNA).
• Shows maternal inheritance — mtDNA is inherited only from the mother (because the egg contributes mitochondria to the zygote, sperm mitochondria are destroyed).
• Contains 70S ribosomes (like bacteria), unlike cytoplasmic 80S ribosomes.

Why Other Options Are Wrong

• Ribosome → Has NO DNA; it is made of rRNA + proteins; it is the site of protein synthesis.
• Mitochondria or Chloroplast alone → Both are correct, so the combined answer is required.