| Criteria | Mitochondria | Chloroplast | Remarks |
| Definition | Double-membrane-bound organelle responsible for aerobic respiration | Double-membrane-bound organelle responsible for photosynthesis | Both are semi-autonomous organelles of endosymbiotic origin. |
| Presence | Present in almost all eukaryotic cells | Present only in plant cells, algae, and some protists | Chloroplasts are absent in animal and fungal cells. |
| Function | Converts chemical energy from glucose into ATP (energy currency of the cell) | Converts light energy into chemical energy stored in glucose | Mitochondria perform catabolic functions; chloroplasts carry out anabolic reactions. |
| Energy Process | Aerobic respiration (oxidative phosphorylation) | Photosynthesis (light-dependent and light-independent reactions) | Both produce ATP, but through different biochemical pathways. |
| Pigments Present | No light-absorbing pigments | Contains chlorophyll a, b, and carotenoids | Pigments in chloroplasts are crucial for capturing solar energy. |
| Internal Structure | Cristae (folds of the inner membrane) increase surface area for respiration | Thylakoids (flattened sacs) organized into grana; stroma surrounds grana | Cristae and thylakoids are functionally analogous as sites of ATP generation. |
| Membranes | Double membrane: outer and highly folded inner membrane | Double membrane plus internal thylakoid membrane system | Chloroplasts have an additional internal membrane system for photosynthesis. |
| Genome | Circular DNA in matrix | Circular DNA in stroma | Both contain their own DNA and can synthesize some proteins independently of the nucleus. |
| Protein Synthesis | Contains 70S ribosomes for limited protein synthesis | Contains 70S ribosomes for partial protein synthesis | Supports the endosymbiotic origin theory; most proteins still encoded by nuclear genes. |
| Enzymatic Pathways | Krebs cycle, β-oxidation, oxidative phosphorylation | Calvin cycle, light-dependent reactions | Each organelle hosts distinct metabolic pathways essential for cell survival and growth. |
| By-products | CO₂, H₂O, and ATP | Glucose (or other carbohydrates), O₂, and ATP | Mitochondria release CO₂; chloroplasts consume CO₂ and release O₂. |
| ATP Production | Produces ATP through the electron transport chain and chemiosmosis | Produces ATP in thylakoid membrane during light-dependent reactions | Mitochondrial ATP is used throughout the cell; chloroplastic ATP is mostly used in situ for carbon fixation. |
| Role in Cell Metabolism | Central to energy release and cellular respiration | Central to energy capture and biosynthesis of sugars | Together, they form the basis of the cellular energy cycle. |
| Matrix/Stroma | Matrix: site of Krebs cycle and DNA location | Stroma: site of Calvin cycle and chloroplast DNA | Both serve as the aqueous compartment for key metabolic cycles. |
| Autonomy | Semi-autonomous; replicates independently of the cell cycle | Semi-autonomous; replicates independently of the cell cycle | Division resembles binary fission, similar to bacteria. |
| Inheritance | Generally maternally inherited in most eukaryotes | Typically maternally inherited in plants | Inheritance is non-Mendelian and extrachromosomal. |
| Evolutionary Origin | Derived from aerobic proteobacteria (α-proteobacteria) | Derived from cyanobacteria | Both originated through endosymbiosis, supporting the endosymbiotic theory. |
| Size and Number | Smaller (~0.5–1 μm in diameter), more numerous per cell | Larger (~4–6 μm), fewer per cell | Size and abundance vary with cell type and metabolic activity. |
| Special Features | Plays a role in apoptosis and calcium signaling | Involved in synthesis of fatty acids, amino acids, and immune signaling in plants | Chloroplasts have broader biosynthetic roles in plant cells; mitochondria are central to cellular stress responses. |
| Oxygen Role | Utilizes oxygen in aerobic respiration | Produces oxygen during photolysis of water | One consumes oxygen, the other produces it—complementary in ecosystem-level energy and gas exchange. |
