| Size |
0.1 – 5 µm |
10 – 100 µm |
10 – 30 µm |
| Shape |
Variable (cocci, bacilli, spirilla, vibrio) |
Variable (generally regular) |
Variable (generally irregular) |
| Multiplication Rate |
Rapid |
Moderate |
Moderate |
| Cell Wall |
Present (peptidoglycan) |
Present (cellulose) |
Absent |
| Glycocalyx |
Present (slime layer or capsule) |
Absent |
Absent |
| Gram Stain |
Gram-positive or Gram-negative |
Not applicable |
Not applicable |
| Plasma Membrane |
Present, selectively permeable |
Present, selectively permeable |
Present, selectively permeable |
| Cell Envelope |
Complex (glycocalyx, cell wall, plasma membrane) |
Simple (cell wall, plasma membrane) |
Simple (plasma membrane) |
| Organelles |
Ribosomes only (70S) |
Membrane-bound organelles (e.g., chloroplasts, mitochondria) |
Membrane-bound organelles (e.g., mitochondria) |
| Energy Production |
Cell membrane (no mitochondria) |
Mitochondria |
Mitochondria |
| Cytoplasm |
Present, main arena of cellular activities |
Present, main arena of cellular activities |
Present, main arena of cellular activities |
| Ribosomes |
70S, involved in protein synthesis |
80S (cytoplasm), 70S (mitochondria, chloroplasts), protein synthesis |
80S (cytoplasm), 70S (mitochondria), protein synthesis |
| Polysome |
Present (polyribosomes) |
Present (polyribosomes) |
Present (polyribosomes) |
| Inclusion Bodies |
Present (e.g., phosphate granules, cyanophycean granules) |
Absent |
Absent |
| Gas Vacuole |
Present in Cyanobacteria and some bacteria for buoyancy (e.g., purple and green photosynthetic bacteria) |
Absent |
Absent |
| Nucleus |
No true nucleus, nucleoid region |
True nucleus, membrane-bound |
True nucleus, membrane-bound |
| Genetic Material |
Circular DNA, plasmids, ds circular, GC-rich |
Linear DNA, chromosomes, ds linear, AT-rich |
Linear DNA, chromosomes, ds linear, AT-rich |
| Plasmids |
Present (e.g., Ffactor, Ti plasmid, AmpR, TetR) |
Absent |
Absent |
| Unique Structures |
Mesosomes, plasmids, chromatophores |
Chloroplasts, large central vacuole, cell wall |
Lysosomes, centrosomes |
| Presence of Centrosomes |
Absent |
Absent |
Present |
| Cell Division |
Binary fission |
Mitosis and meiosis |
Mitosis and meiosis |
| Locomotion Structures |
Undulating flagella |
Generally absent |
Flagella (propeller-like with 360-degree motion) and cilia |
| Examples |
Bacteria, blue-green algae, mycoplasma, PPLO |
Onion peel cells |
Human cheek cells |
