Prokaryotic Cells

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

%%Pro:%% Before

%%Karyotic:%% Nucleus

• 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