A eukaryotic cell is one which contains complex structures bound together by a cell membrane. Large species such as humans, animals and plants and fungi have eukaryotic cells. Eukaryotic cells contain a membrane bound nucleus, this nucleus is what sets eukaryotes apart from prokaryotes.
In addition to being much larger than prokaryotes, eukaryotes have other membrane bound cellular structures in addition to their nucleus. Their cells contain organelles which is the name for their membrane bound structures.
The cell nucleus is bound by a membrane, called the nuclear membrane or nuclear envelope. This double membrane is responsible for what materials go in and out of the nucleus. The cells endoplasmic reticulum, a network of tubules which function in protein transport are extensions of the nuclear membrane. Ribosomes (definition) which are attached to rough endoplasmic reticulum are then modified in protein carrying bodies in the cell known as the Golgi apparatus, or Golgi bodies.
Another membrane bound organelle in the Eukaryotic cell is the Mitochondria, the organelle which is responsible for supplying the cell with energy. The mitochondria have two membranes, the innermost membrane being the place where aerobic respiration occurs.
Many eukaryotic cells contain projections attached to their cytoplasm called flagella or cilia. Flagella are longer projections and cilia shorter ones which are used by the cell as a means of motility.
Centrioles found in Eukaryotic cells usually appear in pairs or groups. They are part of the cytoskeleton (see what are functions of cytoskeleton) which gives the cell its shape.
As previously mentioned, both plants and animals contain Eukaryotic cells. Plant cells have rigid outer cell walls which contain cellulose, hemicelluloses and pectin, which help the plant to maintain its shape. Animal cells lack this cell wall and are therefore more flexible and able to transform themselves into different shapes.
Animal cells also lack chloroplasts (plants use these for photosynthesis) and have smaller vacuoles than plants. Eukaryotic fungal cells are similar to animal cells but have a cell wall made of chitin.
Depending on the type of organism you have, Eukaryotes are either multicellular (many cells) or unicellular. Animals, including humans are multicellular Eukaryotes, and plants are as well. The most common type of unicellular Eukaryote are the protists, who are distinguished from plants, animals and fungi by the fact that they have only one cell and are very difficult to categorize. Paramecium, Amoeba’s and Foraminifera are a few examples of unicellular organisms which are Eukaryotic.
