Eukaryotes and prokaryotes
Bacteria are amongst the simplest of organisms – they are made of single cells. Their cell structure is simpler than the cells of animals, plants and fungi.
- Cells of animals, plants and fungi are called Description of a cell which has a nucleus. Eukaryotic cells also have other structures in the cytoplasm which have membranes around them. cells.
- Cells of bacteria are called Description of a cell which does not have a nucleus - the DNA is free in the cytoplasm. cells.
Diagram not to scale. Prokaryotic cells are smaller than eukaryotic ones
Cells of bacteria do not have a nucleus. Their DNA is present in the cytoplasm of their cells. It is found in a loop. Bacteria can also have much smaller circles of DNA called The small circular genetic material present in bacterial cells and used in DNA recombinant technology.. These are able to move from one cell to another. They provide genetic variation.
Comparing cell types
| Eukaryotic cell | Prokaryotic cell | |
| Size | Most are 5 μm – 100 μm | Most are 0.2 μm – 2.0 μm |
| Outer layers of cell | Cell membrane - surrounded by cell wall in plants and fungi | Cell membrane - surrounded by cell wall |
| Cell contents | Cytoplasm, cell organelles include mitochondria, chloroplasts in plants, and ribosomes | Cytoplasm, ribosomes - no mitochondria or chloroplasts |
| Genetic material | DNA in a nucleus - plasmids are found in a few simple eukaryotic organisms | DNA is a single molecule, found free in the cytoplasm - additional DNA is found on one or more rings called plasmids |
| Type of cell division | Mitosis | Binary fission |
| Size | |
|---|---|
| Eukaryotic cell | Most are 5 μm – 100 μm |
| Prokaryotic cell | Most are 0.2 μm – 2.0 μm |
| Outer layers of cell | |
|---|---|
| Eukaryotic cell | Cell membrane - surrounded by cell wall in plants and fungi |
| Prokaryotic cell | Cell membrane - surrounded by cell wall |
| Cell contents | |
|---|---|
| Eukaryotic cell | Cytoplasm, cell organelles include mitochondria, chloroplasts in plants, and ribosomes |
| Prokaryotic cell | Cytoplasm, ribosomes - no mitochondria or chloroplasts |
| Genetic material | |
|---|---|
| Eukaryotic cell | DNA in a nucleus - plasmids are found in a few simple eukaryotic organisms |
| Prokaryotic cell | DNA is a single molecule, found free in the cytoplasm - additional DNA is found on one or more rings called plasmids |
| Type of cell division | |
|---|---|
| Eukaryotic cell | Mitosis |
| Prokaryotic cell | Binary fission |
A group of organisms called Microorganisms which are similar in size and structure to bacteria but are genetically different. are also prokaryotic.
