Prokaryotes-The+Start+of+Something+New+(Continued)

Classifications

Most high school biology students and teachers use the words “bacteria” and “prokaryotes” interchangeably. However, this is a very grave mistake. Microbiologists divide prokaryotes into two different domains which are **archea** and **bacteria**. Archea are known to be the group of prokaryotes that form methane gas from carbon compounds. Bacteria are the rest of the other types of prokaryotes. Interestingly, archeas have more in common with eukaryotes than they have with bacteria! For example, archea start their translation process (the reading of mRNA to synthesize polypeptide chains) with methionine like eukaryotes while bacteria begin the process with formylmethionine. Also, they don’t contain simple RNA polymerase as bacteria do. Moreover, archea, just like eukaryotes, are not affected by some of the antibiotics unlike most bacteria. Archea are prokaryotes that can adapt to live in harsh environments and can be separated into 3 types based on their ecology and metabolism. They are listed below:

1) Methanogens 2) Extreme Halophiles 3) Extreme Thermophiles

Just like archea, bacteria are also divided into various groups. Some are Gram- Negative Proteobacteria, Cyanobacteria, Gram-Positive Bacteria, Chlamydia, and Spirochetes.

REFERENCES:


 * AP Biology Barron's Review Book (2008 edition)
 * Campbell Biology Textbook
 * Microsoft Encarta Encyclopedia (2006 Edition)