Cell structures come in various shapes and sizes dependent on their location within an organism and what life sustaining process it carries out. These can range from the globular protein of a red blood cell, designed to carry four oxygen molecules at a time to the tail like flagellum of a bacteria designed for mobility and penetration of organs within a body. There are tow major types of cells, prokaryotic cells and eukaryotic cells. An organelle is defined as an internal, membrane bound sac or compartment that serves one or more functions inside the cell. Generally, cell organelles are found more in eukaryotes compared to prokaryotes. One of the main advantages of partitioning the cell interior with these cell organelles is that numerous activities can occur simultaneously in a very confined space. There are different numbers and variation of organelle found in different cells, which is related to their cellular function.
The first of the two types is the Prokaryotic cell, the pro meaning before the nucleus as this cell has no true nucleus.Prokaryotic cells are surrounded by a cell wall and a cells membrane, and in some ways this makes them similar to a plant cell which is eukaryotic, but they have no nucleus or organelles inside, but they do have flagella's and cilia on the outside. The flagellum is a long whip like tail attached to the end of the prokaryotic cell which helps with its movement. The cilia are small spiked hairs that help to transport fluid in and out of the cell and for protection against harmful substances. They are also found in abundance in the eukaryotic cells in the human trachea where they collect dirt, they either by moving it down into the stomach or push it back up into to the mouth to spit it out.
One of the most common prokaryotic cells would be bacteria, they are the smallest cellular organism. It has no true nucleus but it does have a nucleiod region where its DNA is found. It has the flagella