Only two types of cells exist in the world–prokaryotic and eukaryotic. Taxonomists classify bacteria and archaea (organisms similar to bacteria) as prokaryotic. Eukaryotic cells make up protists, fungi, plants and animals. Organisms made up of eukaryotic cells can be either single- or multi-celled.
The presence of a membrane-bound nucleus, among other things, in eukaryotic cells distinguishes them from prokaryotes. The cell nucleus houses DNA strands; in prokaryotic cells, the DNA floats freely in cell cytoplasm.
Cell organelles are membrane-bound structures within eukaryotic cells that perform specific functions to support life in the cell. Examples of cell organelles include ribosomes, chloroplasts (in plants), endoplasmic reticulum, mitochondria, lysosomes and golgi apparatus.
Eukaryotic cells contain cytoskeletons similar in function to the skeleton of a human or animal. The cytoskeleton gives the cell shape and allows for movement of the cell and movement of the organelles within. The cytoskeleton also aids in cell division. Microtubules and microfilaments make up a cell's cytoskeleton.
The structure of DNA in eukaryotic cells resembles strands or filaments. DNA exists as chromosomes. In prokaryotes, the DNA is circular with no chromosomes present.
A phospholipid bilayered plasma membrane surrounds eukaryotic cells. Transporting and signalling processes occur at this plasma membrane.
