Why are mitochondria known as semi-autonomous organelles?
GeneralClass 12AllAnswered 27 Mar 2026
Answer
Mitochondria are semi-autonomous because:
Autonomous features:
- Own DNA: Circular, double-stranded mtDNA (16.5 kb in humans)
- Own ribosomes: 70S type (prokaryotic, not 80S eukaryotic)
- Self-replication: Divide by binary fission independent of cell cycle
- Protein synthesis: Synthesize ~13 proteins encoded by mtDNA
Dependent features:
- Nuclear genome dependency: Most mitochondrial proteins (~1000) encoded by nuclear genes
- Import machinery: Requires cytoplasmic proteins synthesized on free ribosomes
- Lipid synthesis: Mitochondrial membrane lipids from ER
Endosymbiotic origin: 70S ribosomes, circular DNA, and double membrane support the theory that mitochondria evolved from aerobic prokaryotes engulfed by ancestral eukaryotic cells.
Maternal inheritance: mtDNA inherited exclusively from the ovum (mother).
Suggested Q&A
General · Class 12- GeneralClass 12Electric Field at Centre of Ring with Non-Uniform Charge Distribution. Four quadrants carry linear charge densities: +2λ, −2λ, +λ, −λ. Find electric field at centre.
- GeneralClass 12P°(hexane) = 408 Torr, P°(heptane) = 141 Torr. x(hexane) = 0.300. Find Y₆ and Y₇.
- GeneralClass 122N₂O₅(g) → 4NO₂(g) + O₂(g). Initial P = 50 mmHg; P at 30 min = 87.5 mmHg. Find P at 60 min.
- GeneralClass 12What is the difference between psychosis and neurosis?
- GeneralClass 12What is the difference between prism and a pyramid?
- GeneralClass 12What is the difference between phrase and clause?