Prokaryotic Cells

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Prokaryotic Cells

Prokaryotes, such as bacteria, are cells that contain no organelles or any membrane-bound internal structures. As such they are single celled organisms.

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Cell Wall

The cell wall provides structural rigidity and acts a protective layer to the cell. The cell wall is outside of the cell membrane and helps to prevent lysis (spliting due to increased volume) of the cell. Bateria cell walls are made of peptidoglycans.

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Cell Membrane

The cell membrane is a phospholipid bilayer that contains protein channels that allow for the selective entrance and exits of molecules from the cell. The membrane prevents the diffusion of ions, proteins and other molecules out of the cell.

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Cell Capsule

Some prokaryotes also have a cell capsule. The capsule allows it to attach to surfaces and helps to protect it from dehydration and attack by immune systems. 

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Flagella and Pili

Some prokaryotes have flagella, they are for locomotion.

Some also have pili, these are for attaching to surfaces. 

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DNA

As prokaryotes have no nucleus the DNA is free in the cytoplasm. The DNA is in the form of baterical chromosomes and plasmids in prokaryotes. A plasmid is a circular double helix of DNA that replicates independently of the bacterial chromosome.Image result for plasmid (http://bio1151.nicerweb.com/Locked/media/ch20/20_02a.jpg)

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Ribosomes

Ribosomes in prokaryotes are smaller than those in eukaryotes. They are also found freely within the cytoplasm.Image result for ribosomes in prokaryotes (http://biosiva.50webs.org/transl6.gif)

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