Organisms are made up of cells. Most organisms are multicellular and have cells that are specialised to do a particular job. Microscopes are needed to study cells in detail.
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 bacteria are called prokaryotic cellA simple cell that does not have a nucleus – the DNA is free in the cytoplasm. .
Cells of animals, plants and fungi are called eukaryotic cellA type of cell that has a nucleus..
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 ArchaeaMicroorganisms which are similar in size and structure to bacteria but are genetically different. are also prokaryotic.