Prokaryotes
<p>There are two major kinds of prokaryotes:
<b>Bacteria
Archaea </b>(single-celled organisms)
As you may have read earlier in this unit, biologists now estimate that each human being carries nearly 20 times more bacterial, or prokaryotic, cells in his or her body than human, or eukaryotic, cells. If that statistic overwhelms you, rest assured that most of these bacteria are trying to help, and not hurt, you. Numerically, at minimum, there are 20 times more prokaryotic cells on Earth than there are eukaryotic cells. This is only a minimum estimate because there are trillions of trillions of bacterial cells that are not associated with eukaryotic organisms. In addition, all Archaea are also prokaryotic. As is the case for bacteria, it is unknown how many Archaean cells are on Earth, but the number is sure to be astronomical. In all, eukaryotic cells make up only a very small fraction of the total number of cells on Earth. 
 
There are four main structures shared by all prokaryotic cells, bacterial or Archaean:
 
<b>The plasma membrane
Cytoplasm
Ribosomes
Genetic material (DNA and RNA)</b>
 
<img src="/174637d9-df9a-5214-ac5a-6ff187a2f198.png"/>      <img src="/401b0e81-de45-566b-803c-423098a8ece6.png"/>
 
 
 
 
 
 
 
 
 
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