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 of bacteria are called Description of a cell which does not have a nucleus - the DNA is free in the cytoplasm..
The two types of cell compared:
| Feature | 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, ribosomes and chloroplasts in plants. | Cytoplasm, ribosomes present; there are 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. |
| Feature | Size |
|---|---|
| Eukaryotic cell | Most are 5 μm - 100 μm. |
| Prokaryotic cell | Most are 0.2 μm - 2.0 μm. |
| Feature | Outer layers of cell |
|---|---|
| Eukaryotic cell | Cell membrane, surrounded by cell wall in plants and fungi. |
| Prokaryotic cell | Cell membrane, surrounded by cell wall. |
| Feature | Cell contents |
|---|---|
| Eukaryotic cell | Cytoplasm, cell organelles include mitochondria, ribosomes and chloroplasts in plants. |
| Prokaryotic cell | Cytoplasm, ribosomes present; there are no mitochondria or chloroplasts. |
| Feature | 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. |
A group of organisms called A type of single-celled microorganisms. They are similar to bacteria, and are usually found in extreme conditions such as hot springs. are also prokaryotic.