Every living thing in the world is made up of one or more cells, but these cells can be profoundly different. A domain is the highest level of organization for all living things and they divide all cells into three factions: Eukaryotes, Bacteria, and Archaea. The organisms that are only made up of one cell in the factions of Bacteria and Archaea are also called prokaryotes. Animal cells, plant cells, fungi, and protists are eukaryotes.
The three domains of life encompass all living things on Earth.
AJC1 at Flickr.com
All cells have four things that are the same:
1) an outer cover, called the membrane, that separates the inside of the cell from the outside world
2) a part of the cell that feels like jelly where all other cell parts are found
3) DNA, the genetic matter of the cell
4) ribosomes, parts that make proteins.
However, bacteria and archaea are different from eukaryotic cells in several ways.
Eukaryotes
Most of these organisms you study around you are made of Eukaryotic cells. Many organisms in this domain are made of more than one cell and there are likely a few of them sitting in chairs next to you right now. Cells in this domain are far more organized and found in larger and more complex living things in comparison to the other two domains.
A eukaryotic cell is a cell that has a membrane-bound nucleus and other smaller parts called organelles. The word "organelle" means "little organ," and they all do different jobs in the cell.
Plants, animals, and fungi have eukaryotic cells.
AJC1 at Flickr.com
Prokaryotes
Bacteria Cells
A bacterial cell is a simple, single-celled organism that doesn't have a nucleus or any other membrane-bound organelle. Remember, a membrane is an outer cover that separates the cell from the outside world. Bacteria have a cell wall that helps keep it safe, helps the cell keep its shape, and keeps it from losing too much water. The capsule lets the cell to hook on to surfaces in its environment.
Some prokaryotes have flagella, which cells use to move or make more cells. These cells make more cells through binary fission, where one cell divides into two new cells. Through this process, a group of bacteria are able to quickly change over time to change to their environment.
Bacteria are made of one prokaryotic cell.
Openstax Concepts of Biology
Archaea Cells
Archaea are a domain of living things with only one cell that don't have a nucleus or organelles. Many of them live in places throughout the world where other cells cannot. Since they have no cell nucleus or any other organelles inside their cells, they are just like bacteria.
Archaea copy itself using binary fission. Archaea are able to swim due to one or more tail-like flagella. Even though we are still learning about archaea, we still don't know a lot about this group of cells.
Archaea can survive under extreme conditions, like the thermal pool shown in this picture.
Steve Jurvetson at Flickr.com
References
Content adapted by the RocketLit team from:
Rice University, Openstax CNX. "3.2 Comparing Prokaryotic and Eukaryotic Cells." cnx.org, 2017. <
https://cnx.org/contents/s8Hh0oOc@9.25:EaHMyDB_@6/Comparing-Prokaryotic-and-Euka>
http://eol.org/info/457