All eukaryotic cells possess a cell membrane, cytoplasm, a nucleus, nucleic acids, and ribosomes. While the cytoplasm, nucleic acids and ribosomes in eukaryotic cells are similar to those in prokaryotic cells (Lesson 3.2), there are notable differences in the cell membrane.
All living cells have a cell membrane. Acting as a physical barrier, the cell membrane separates the cell from its environment. Acting as a diffusion barrier, the cell membrane selects what materials enter or leave the cell. Not all molecules that come in contact with the cell will be able to enter or leave.
Unlike the cell membrane of prokaryotic cells, eukaryotic cell membranes also allows communication between the cell and its environment. Specific proteins on the cell membrane are able to send and to receive chemical signals from other eukaryotic cells. This is especially true in multi-cellular organisms such as you. For example, cells in your body possess specific receptor proteins for human growth hormone, which, as the name implies, aids your body in the process of growing.
In addition, all eukaryotic cells possess membrane bound organelles. The term “organelles” can be interpreted as “little organs”. As with organs in humans, each of these membrane bound structures has a specific function that helps the cell, as a whole, to function properly.
Organisms that are composed of eukaryotic cells include plants, animals, fungi, and protists. While all eukaryotic cells have some structures in common, not all of them will have the same number or same type of individual organelles. In this lesson, we will observe these differences only between animal and plant cells..
To help you with this process, fill in the Eukaryotic cell structure sheet as chart as you work your way through this material.