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. $Prokaryotes do not have a membrane-bound <strong>nucleus</strong>$, but they do have a general area in the cell where the DNA resides.

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• 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.

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

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Prokaryotic vs. Eukaryotic Cells

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

Common Shapes of Prokaryotic Cells

• Cocci
• Bacilli
• Spirilli

 Edited: 05 October 2022