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Do Prokaryotes Have a Cell Membrane?

Instructor: Stephanie Matalone

Stephanie taught high school science and math and has a Master's Degree in Secondary Education.

This lesson will delve into the details of what prokaryotes and cell membranes are. It will then answer the question of whether or not prokaryotic cells have cell membranes and why they are important.

Prokaryotes

There are two main types of cells, prokaryotes and eukaryotes. Prokaryotes are simpler cells that tend to make up single-celled organisms like bacteria, while eukaryotes are more complicated cells that usually make up larger organisms like plants and animals.

Eukaryotes are characterized by the presence of many organelles which are compartments in the cell that have specialized jobs such as the mitochondria that is responsible for energy production. Prokaryotes lack most organelles, most notably the nucleus which is responsible for all activities that go on in the cell and houses the genetic information.

Prokaryotes do have a few organelles including ribosomes that make proteins and a cell membrane that protects the cell. These organelles are also found in eukaryotes.

Prokaryote
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Eukaryote
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Cell Membrane

Think of the cell membrane as a water balloon that holds the water inside the balloon. The cell membrane holds everything inside the cell including the cytoplasm, a gooey material the fills up the inside of the cell just as the water fills the inside of the balloon. All the organelles of a cell are suspended in the cytoplasm and surrounded by the cell membrane.

Not only does the cell membrane hold the contents of the cell together, it also protects the cell like a bouncer at a club. The cell membrane decides what materials can enter the cell just as a bouncer decides what people can enter the club. There are special proteins channels embedded in the cell membrane that allows certain molecules to cross into the cell as needed.

The cell membrane is also called the phospholipid bilayer. This is because it is composed of two phospholipid molecules that are oriented towards each other. The phosphate head of each phospholipid molecule is hydrophilic, meaning it is attracted to water which is why they are oriented towards the outside and inside of the cell. The lipid tail of each phospholipid molecule is hydrophobic which means it is not attracted to water. This is why tails are oriented toward each other so they are away from the water inside and outside of the cell.

Cell Membrane
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