A eukaryote is any organism whose cells contain a nucleus and other structures
(organelles) enclosed within membranes. The defining membrane-bound
structure that sets eukaryotic cells apart from prokaryotic cells is the nucleus,
enclosed by the nuclear envelope, which contains the genetic material. The
presence of a nucleus gives eukaryotes their name. Most eukaryotic cells also
contain other membrane-bound organelles such as mitochondria or the Golgi
apparatus. In addition, plants and algae contain chloroplasts. Many unicellular
organisms are eukaryotes, such as protozoa.
A prokaryote is a single-celled organism that lacks a membrane-bound nucleus.
All the intracellular water-soluble components (proteins, DNA and metabolites)
are located together in the same volume enclosed by the cell membrane, rather
than in separate cellular compartments. Prokaryotic cells can be divided into two
domains, Archaea (domain or kingdom of single-celled microorganisms. These
microbes are prokaryotes, meaning they have no cell nucleus or any other
membrane-bound organelles in their cells) and Bacteria. In cell biology,
an organelle is a specialized subunit within a cell that has a specific function.
The name organelle comes from the idea that these structures are to cells what
an organ is to the body (hence the name organelle). There are many types of
organelles, particularly in eukaryotic cells. Prokaryotes do not possess
organelles. Organelles are also known as cell compartments. Eukaryotic cells
have membrane-bound compartments in which specific metabolic activities take
place.
Prokaryote (cell structure of bacterium)
Eukaryote (cell structure of bacterium)
The Golgi apparatus, also known as the Golgi complex, Golgi body, or simply
the Golgi, is an organelle found in most eukaryotic cells. All multicellular
organisms are eukaryotes, including animals, plants and fungi.
Paramecium is a genus of unicellular Ciliate protozoa, commonly studied as a
representative of the Ciliate group. Paramecia are widespread
in freshwater, brackish and marine environments, and are often very abundant in
stagnant basins and ponds. Some species are readily cultivated and easily
induced to conjugate and divide.
Protozoa are a diverse group of mostly mobile unicellular eukaryotic organisms.
Historically, protozoa were defined as unicellular protists with animal-like
behavior, such as movement.