What are the Parts of a Eukaryotic Cell?
As you read through each of these features of eukaryotic cells, it is important to realize that while most of these parts can be bound in all eukaryotic cells, not all of them are found in all eukaryotic cells.
All plant cells have a cell wall. The cell wall is a rigid structure that supports the cell and surrounds the cell membrane. The cell wall of a plant cell is made of a type of sugar called cellulose. Fungi (singular fungus), such as yeasts and mushrooms, also have cell walls. The cell walls of fungi are made of a sugar (carbohydrate) called chitin. Prokaryotic cells such as bacteria and archaea also have cell walls that are often constructed of peptidoglycan. Animal cells and protists do not have this structure.
All cells have a cell membrane. The cell membrane is a flexible protective barrier that surrounds all cells. It separates the cell from the outside environment. However, the primary purpose of the cell membrane is to control what substances can enter and leave the cell. In cells that have a cell wall, the cell membrane is found just inside the cell wall.
The cell membrane is made of different materials. It contains proteins, carbohydrates, and phospholipids. Proteins are molecules made by the cell for a variety of functions. Lipids are compounds that do not dissolve in water. They include fats and cholesterol. Phospholipids are lipids that contain the element phosphorous.
The proteins and lipids in the cell membrane control the movement of materials into and out of the cell. A cell needs materials such as nutrients and water to survive and grow. Nutrients and wastes go in and out of the cell through the proteins in the cell membrane. Water can pass through the cell membrane without the help of proteins.
