Which of the following organelles have their own DNA and ribosomes?
- (a)Endoplasmic reticulum and Golgi bodies
- (b)Mitochondria and Chloroplast
- (c)Endoplasmic reticulum and cytoskeleton
- (d)Cell wall and nucleolus
Correct — B, Mitochondria and Chloroplast. These two are the semi-autonomous organelles: each carries its own small circular DNA and its own 70S ribosomes, a legacy of their free-living bacterial ancestors (the endosymbiotic theory), which lets them make some of their own proteins.
- (a)Endoplasmic reticulum and Golgi bodies — The ER and Golgi apparatus process, fold and package proteins and lipids, but neither contains DNA or its own ribosomes; the ribosomes on rough ER belong to the cytoplasm, not to the organelle.
- (c)Endoplasmic reticulum and cytoskeleton — The cytoskeleton is a protein scaffold of microtubules and filaments and has no genetic material; the ER, as above, has no DNA of its own.
- (d)Cell wall and nucleolus — The cell wall is a non-living outer covering with no DNA, and the nucleolus (inside the nucleus) makes ribosomes but is not itself a DNA-plus-ribosome organelle in the sense asked.
Most cell organelles depend entirely on the nucleus for their genetic instructions. Mitochondria and chloroplasts are exceptions — they are 'semi-autonomous', carrying their own DNA and ribosomes and dividing on their own. This supports the endosymbiotic theory, which holds that both arose from ancient free-living prokaryotes engulfed by an early cell.
The question tests which organelles are partly self-governing. The trap options pair up organelles that handle proteins or structure (ER, Golgi, cytoskeleton) or coverings (cell wall) — busy, important structures, but without their own genome. Only mitochondria and chloroplasts satisfy 'own DNA and ribosomes'.
- Mitochondria and chloroplasts both contain their own circular DNA and 70S ribosomes.
- This semi-autonomy underpins the endosymbiotic theory of their prokaryotic origin.
- Mitochondria carry out aerobic respiration; chloroplasts carry out photosynthesis.
- The endoplasmic reticulum, Golgi apparatus, lysosomes and cytoskeleton have no genome of their own.
Only mitochondria and chloroplasts are semi-autonomous (own DNA + ribosomes) — hence option (b).
- The ribosomes studding the rough ER are cytoplasmic ribosomes, not DNA-bearing organelles.
- The nucleolus makes ribosomes but is a sub-region of the nucleus, not a separate DNA-plus-ribosome organelle.
This is asked as 'which organelle(s) have their own DNA / genetic material', with ER, Golgi and lysosomes as distractors.
Which organelle in the cell, other than nucleus, contains DNA?
- (a) Centriole
- (b) Golgi apparatus
- (c) Lysosome
- (d) Mitochondrion
Answer(d) Mitochondrion
The same idea, narrowed to one organelle — UPSC asked which non-nuclear organelle contains DNA (the mitochondrion), the very property (own DNA) that, together with chloroplasts, makes the pair in this NDA question the correct answer.
Which of the following two cell organelles have their own genetic material?
- (a) Endoplasmic reticulum and plastids
- (b) Endoplasmic reticulum and mitochondria
- (c) Mitochondria and plastids
- (d) Lysosomes and Golgi apparatus
Answer(c) Mitochondria and plastids
Essentially the same question one session earlier — NDA-II 2024 asked which two organelles have their own genetic material (mitochondria and plastids/chloroplasts), matching this item's 'own DNA and ribosomes' pairing.
- practice — not a real PYQ
The presence of their own DNA and ribosomes in mitochondria and chloroplasts is the main evidence for which theory?
- (a)Cell theory
- (b)Endosymbiotic theory
- (c)Fluid mosaic model
- (d)Germ theory
Answer(b) Endosymbiotic theory — the semi-autonomy of these organelles points to a prokaryotic origin.
- practice — not a real PYQ
The type of ribosomes found inside mitochondria and chloroplasts is
- (a)80S
- (b)70S
- (c)60S only
- (d)no ribosomes
Answer(b) 70S — the same size as bacterial ribosomes, consistent with their endosymbiotic origin.