Prokaryotes & Eukaryotes
- Animal and plant cells are types of eukaryotic cells, whereas bacteria are a type of prokaryote
- Prokaryotes have a cellular structure distinct from eukaryotes:
- Their genetic material is not packaged within a membrane-bound nucleus and is usually circular (eukaryotic genetic material is packaged as linear chromosomes)
- Prokaryotes lack membrane-bound organelles
- Eukaryote cells are compartmentalized to create partitions within the cell for specialized reactions to take place
- Prokaryote cells are many (100s/1000s) of times smaller than eukaryotic cells
- Their ribosomes are structurally smaller (70 S) in comparison to those found in eukaryotic cells (80 S)
A Prokaryotic Cell's Structural Features Diagram
Prokaryotic cells are often described as being ‘simpler’ than eukaryotic cells, and they are believed to have emerged as the first living organisms on Earth.
Prokaryotic & Eukaryotic Cells Comparison Table
| FEATURE | PROKARYOTES | EUKARYOTES |
| Size | 0.5 - 5 µm diameter | Up to 100 µm diameter |
| Genome | DNA circular with no proteins, in the cytoplasm | DNA is associated with histones (proteins), formed into chromosomes |
| Cell division | Occurs by binary fission, no spindle involved | Occurs by mitosis or meiosis and involves a spindle to separate chromosomes |
| Ribosomes | 70S ribosomes | 80S ribosomes |
| Organelles | Very few No membrane-bound organelles |
Numerous types of organelle Membrane-bound Single membranes: lysosomes, Golgi, vacuoles Double membranes: nucleus, mitochondria, chloroplast No membrane: ribosome, centriole, microtubules |
| Cell wall | Made of peptidoglycan (polysaccharide and amino acids) and murein | Present in plants (made of cellulose or lignin) and fungi (made of chitin, similar to cellulose but contains nitrogen) |
