Kingdom Monera

Basic Info Are the smallest living cells that can be seen under a microscope. Live in all environments; very diverse habitats. Very diverse metabolisms. Contain NO nucleus. Are autotrophic and heterotrophic. The Kingdom Monera includes the greatest number of organisms on earth

Two domains: Eubacteria and Archaebacteria Eubacteria require oxygen to live. Archaebacteria are ancient bacteria and live in extreme environments (high temperatures, high salt, or high acidity. However they are also found in soils, oceans and marshlands

Archeabacteria  Their cell membranes are composed of different proteins than eubacteria.  Are important in carbon, nitrogen, and sulfur cycles.

Halophiles live in high salt environments.  Great Salt Lake in Utah

Thermophiles live in hot springs. They use sulfur to produce energy.

 Methogens produce methane gas from carbon dioxide and hydrogen. Methogens also digest cellulose in the guts of cows.

Eubacteria All other bacteria. Vital in decomposing materials, fixing nitrogen, digestion, and making certain foods.

Structure Bacteria are prokaryotic cells.  They are simple cells.  Contains a cell wall, cell membrane, nucleoid region (DNA), ribosomes, and cytoplasm (gel like).  Single-stranded circular DNA.  Some bacteria also have a flagellum (movement) and pilli.  Some have a slime layer (known as a capsule).

Shapes and Sizes  Bacteria come in many different sizes and shapes.  Bacteria colonies will have one of the following three shapes: Cocci (spherical) Bacilli (rod-like) Spiral

o They will group together in pairs, chains, or clusters.

Gram Positive and Negative Gram Positive bacteria have a cell membrane and a thick cell wall made from peptidoglycan.

 Gram negative bacteria have a cell membrane, a thin layer of petidoglycan, and an outer cell membrane. The outer membrane is also known as LPS (lipopolysaccarhride) or endotoxin.

Replication and Cell Division Occurs by binary fission:  First, there is the replication of the bacterial genome.  Then the cell wall extends.  Next is production of a septum, which is a wall that divides the cell into two daughter cells. The septum grows from opposite sides towards the center of the cell, causing cleavage of the daughter cells.

 Incomplete cleavage causes bacteria to remain linked forming chains or clusters.

There are also three ways in which bacteria can exchange DNA:

Transduction Transduction: DNA transferred from one cell to another via viruses.

Conjugation Conjugation: Is the transfer of genetic material through direct cell to cell contact. The DNA is transferred through the pilius.

Transformation Transformation: When bacteria die, some may release DNA which can be taken up by another and form to produce genetically different cells.

Spores Some gram positive bacteria (Clostridium and Bacillius), under very harsh conditions will convert to a dormant stage; a spore.  A spore is a dehydrated structure with multiple layers that helps to protect the bacterium.  The spore will contain a copy of the bacterium’s genome, and only the essential proteins.

Bacterial Growth Occurs in four stages: Lag, exponential, stationary, and decline (or death).

The lag phase is the period before the bacteria begin dividing. The bacteria are adjusting to a new environment. The exponential phase is when the bacteria are dividing and growing. Eventually the culture will run out of nutrients and enter the stationary phase.

If no new nutrients become available, the culture will continue to not grow, toxins will build up, and eventually the culture will decrease and enter the decline phase.

Common Bacteria on the Human Body Normal Flora- All the microorganisms normally found on the surface tissues of humans. We have more bacterial cells on us than we do our own cells.  Not all bacteria are harmful!! If it was not for some bacteria in our intestines, we would not be able to digest certain foods. Some common bacteria in the intestines: E.coli, Clostridium, Lactobacillus, and Bifdiobacteria. Majority of the bacteria living in the gut are gram negative bacillus bacteria (all enteric bacteria).

Some bacteria are even helpful in making the food we eat! Many bacteria are helpful in making dairy foods.

Other bacteria help in the biochemical cycles. All proteins contain lots of nitrogen. The atmosphere is 80% nitrogen. However, we can’t directly use atmospheric nitrogen, because it is in the wrong form: N 2. We need it in the ammonia form: NH 3.

Nitrogen fixing bacteria are able to do this conversion. Most of them live in root nodules of certain plants, the legumes, such as alfalfa and soybeans. Farmers plant these crops to enrich their soil by naturally adding ammonia to it. The nitrogen-fixing bacteria live in the soil and invade the nodules of young plants. Plants also need nitrogen in the form of nitrate, NO 3. Nitrifying bacteria convert ammonia to nitrate