BACTERIA

Bacteria

Bacteria are prokaryotic, unicellular organisms. Bacteria are very small; so much so that 1
billion could fit on 1 square centimeter of space on the human gums, and 1 gram of digested
food has 10 billion bacteria. Bacteria are the simplest living organisms. Previously they fell
under the Kingdom Moneran, but now they fall into two different Kingdoms: Archaebacteria
and Eubacteria. There are several differences between the two.

Archaebacteria have no peptidoglycan in their cellular walls. They also have odd lipids in their
cell walls. Many are able to live in extreme places (like early Earth). There are 3 types of
Archaebacteria. The first type is Methanogen. These use Carbon dioxide and Hydrogen to
make Methane. They are found in sewage, cows, and swamps, and they do not take in oxygen.
The second type is Extreme Halophile. These live in extremely salty places (i.e.: the dead sea
and great salt lake). Finally, the third type is Thermoacidophiles. These prefer extremely hot,
acidic areas (i.e.: hot springs and volcanos).

Eubacteria have peptidoglycan in their cell walls, and they have no unusal lipids. They have
three shapes: bacilli (hot dog shaped), cocci (ball shaped), and spirilli (spring shaped).
Eubacteria can also have prefixes before their names: strepto, indicating chains of the shaped
bacteria, and straphylo, indicating clusters of the shaped bacteria. Eubacteria are tested in
labratories for Gram stains. Gram stains will determine if antibiotics will work (Gram postive)
or if they will not (Gram Negative). There are four major types of Eubacteria: Cyanobacteria
(green bacteria that infest fertilizer polluted ponds and lakes and mass produce algae),
Spirochetes (Gram negative bacteria on which antibiotics do not work), Gram Positive (both
gram positive that are used to make yogurt, streptthroat is one of these), and Proteobacteria (Ecoli).
Bacteria also have special structures: Plasmids (a small loop of DNA separate from the
nuclear region, which is used for creating genetic variety, inserting into other organisms, and
by genetic engineers) and Endospores (hard coat created by some bacteria in extreme
conditions--this is why canning jars must be boiled for a long time).

Reproduction is either through binary fusion (splitting of a cell with no variety in its genes) or
through several other forms that produce genetic variety: Transformation (taking DNA from
environment and incorparting it into themselves), Conjugation ("sex" in which cilia hook
together and the Plasmids exchange genes), and transduction (viri infect the bacteria and the
bacteria infects the virus with its Plasmid to move genes throughout the population).

Bacteria produce poisons that can cause sickness: exotoxins, which are given off by the Gram
positive bacteria, and endotoxins, which are given off by Gram negative bacteria as they die.