Prokaryotic Cells

• Prokaryotes are the most basic living organisms. These were the first cells that appeared on Earth.

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• Animals and plants, along with other eukaryotes, have a nucleus where DNA is stored in the cell. Prokaryotes do not have a membrane-bound nucleus, but they do have a general area in the cell where the DNA resides.

• There are two basic types of prokaryotes: Bacteria and Archaea.

• Archaea are the more ancient group and, as a result, tend to live in extreme environments – salty lakes, the bottom of the ocean, and very hot environments.

• Bacteria are found everywhere – in your body, on your skin, on practically every surface and place on Earth.

• Prokaryotes can be both helpful and harmful to other living organisms.

Cell Theory

The Cell Theory applies to all living things and has three principles:

1. Every living thing is made of cells.

2. Cells come from existing cells.

3. Cells are the basic unit of structure and function.

   

Structure

The function of a cell usually determines its structure.

• All cells must have a cell membrane. Cell membranes surround the cell and serve as a barrier to the outside environment.
• All cells must have genetic material (DNA).
• All cells must have ribosomes. Ribosomes are used to produce proteins.
• All cells have cytoplasm. Cytoplasm fills the free spaces in the cell, holding the parts of a cell in place.

Prokaryotic vs. Eukaryotic Cells

• Eukaryotic cells have a nucleus, unlike prokaryotic cells.
• Prokaryotes have a cell wall for protection, keeping shape, and preventing the cell from bursting. Some eukaryotes have cell walls, but not all.

Common Shapes of Prokaryotic Cells

• Cocci

• Bacilli

• Spirilli

  Edited: 05 October 2022