Welcome to the Exciting World of Bacteria!!!

What is Bacteria? Bacteria occur in almost every environment on Earth, from the bottom of the ocean floor, deep inside solid rock, to the cooling jackets of nuclear reactors. Possible bacteria-like structures have even been recovered from 3 billion year old Martian meteorites. The taxonomic Kingdom Monera consists of the bacteria. Organisms in this group lack membrane-bound organelles associated with higher forms of life. Such organisms are known as prokaryotes. Eubacteria and cyanobacteria are the major forms of life in this kingdom. The most primitive group, the archaebacteria, are today restricted to difficult environments, such as hot springs or areas of low oxygen concentration. Their small size, ability to rapidly reproduce, and diverse habitats/modes of existence make monerans the most abundant and diversified kingdom on Earth. _________________________________________ Bacteria are single cell, prokaryotic organisms. Their main parts are as follows: 1. Capsule - outside protective layer usually found on disease causing bacteria. 2. Cell Wall - next layer in that gives bacteria their shape and additional durability. 3. Cell Membrane (plasma membrane) - permeable membrane that has a variety of functions, including bringing chemicals and nutrients in and out of the cell through diffusion or active transports. 4. Cytoplasm - gel-like material inside cell that protects cell parts and helps move materials around the cell. 5. Ribosomes - makes various protiens. 6. DNA - genetic material that controls the functions of the cell. The "genes" of the organism. 7. Flagella - a tail used moving around. They can none or many of these. 8. Pilus - small hairs used for sticking to surfaces or each other. Also used in reproduction. Can have none or many.

What Different Shapes can Bacteria come in?

Bacteria typically have one of three shapes: rods (bacilli), spheres (cocci) or spiral (spirilla).

The below picture is an example of the ball-shaped cocci. The picture is of streptococci.


The shapes again, with examples and plural forms are:

Round (coccus, plr. cocci)
Example:Staphylococcus epidermidis

Rod (bacillus, plr. bacilli)
Example: Escherichia coli

Spiral (spirillum, plr. spirilla)
Example: Treponema pallidum

How do Bacterium get nutrients?

Nutrition refers to how an organism obtains energy and a carbon source. Phototrophs are species that use light energy, and chemotrophs obtain their energy from chemicals taken from the surrounding environment. An autotroph is an organism that only needs carbon dioxide as its carbon source, and a heterotroph is an organism that requires at least one organic nutrient as a source of carbon for making other organic compounds. The four major modes of nutrition for prokaryotes are:

1. Photoautotrophs are photosynthetic organisms that harness light energy to drive the synthesis of organic compounds from carbon dioxide. All photosynthetic prokaryotes use this mode of nutrition.

2. Chemoautotrophs only require carbon dioxide as a carbon source. Instead of using light for energy, they obtain energy by oxidizing inorganic substances. Only certain prokaryotes use this mode of nutrition.

3. Photoheterotrophs may use light to make ATP but must also obtain carbon in organic form. Only certain prokaryotes use this type of nutrition.

4. Chemoheterotrophs consume organic molecules for energy and carbon. Prokaryotes, protists, fungi, animals and some plants use this nutritional mode.

Most bacteria are heterotrophic, living off other organisms. Most of these are saprobes, bacteria that live off dead organic matter. The bacteria that cause disease are heterotrophic parasites. There are also many non-disease-causing bacterial parasites, many of which are helpful to their hosts.


Autotrophic bacteria manufacture their own food by the processes of photosynthesis and chemosynthesis (see autotroph ). The photosynthetic bacteria include the green and purple bacteria and the cyanobacteria . Many of the thermophilic archaebacteria are chemosynthetic autotrophs.

How do Bacterium Reproduce? In bacteria DNA is organized in a continuous strand of genetic material. This circle of DNA is localized in an area called the nucleoid, but there is no membrane surrounding a defined nucleus as there is in the eukaryotic cells of protists, fungi, plants, and animals. Bacterial cells may also include one or more plasmids, circular strands of separated DNA that is able to independently replicate. Genetic Recombination: Conjugation- During this method two cells pass each other sending DNA from the so called "male" cell to the "female" cell by means of a sex pilus, which is a hair like structure on the outside of the bacteria cell. Transformation- This method is when the bacteria collect parts of DNA that have been released into water of soil by the decomposing dead bacteria. Transduction- Transduction occurs when bacteriophages or viruses that infect bacteria carry parts of DNA from cell to cell. After one of these types of genetic recombination, binary fission takes place and the cell begins to grow. Almost like a lady who is pregnant begins to grow. While in this stage the cell is expanding and molecule copies itself and travels to opposite ends of the cell. Then once the cell has expanded to a certain point the cell's cytoplasm pinches in half and divides into 2 daughter cells. These cells then repeat the process as frequently as every 6 minutes. Before long you have a new colony of bacteria that has been developed. Divisions of Bacteria and Examples There are three main divisions of life, they are Domain Bacteria, Domain Archaea, and Domain Eukarya. This section will be focusing on Domain Bacteria, and Domain Archaea. Each of these domains has its own subdivisions, whcih will be covered below. There are five main groupings of Domain Bacteria, these are grouped by similarities in ribosomal RNA. They are: 1. Proteobacteria: This is the most diverse type of bacteria, and it has three main subgroups. ---a. Purple Bacteria: Purple bacteria can be either photoautotrophic or photoheterotrophic. Many of these bacterium get nutrients from sulfur-containing compounds, and do not release oxygen as a waste product, but sulfur instead. These bacterium are usually found in sediments of ponds, lakes, and mud. Many have flagella or tales as a means of transport. ---b. Chemoautotrophic Proteobacteria: These bacterium live symbiotically in the roots of some plants such as legumes as well as other vegetables and contribute to their absorbtion of nutrients. Some species do this by converting nitrogen from the air into helpful nitrogen-containing minerals plants can use. These bacterium also help out with chemical cycles of ecosystems such as nitrogen fixation. ---c. Chemoheterotrophic Proteoacteria: These bacterium, such as the enteric bacterium Salmonella, can, in some cases be harmful. They live in the intestinal tracts of humans and animals and are usually rod-shaped. The micro-organisms that have been known to cause food poisoning are chemoheterotrophic bacterium. 2. Gram-positive Bacteria: This group includes mainly gram-positive bacterium, but some gram-negative bacterium as well because of similarities between some of the species'. Most of the species included in this group are chemoheterotrophs, but some are photosynthetic. As you can see this group covers a variety of species. ---a.Chemoheterotrophic Gram-positive Bacteria: These are typically what you would think of when talking about gram-positive bacteria. They form endospores that are able to survive in harsh conditions. ---b.Mycoplasmas: Mycoplasms do not form spores like the chemoheterotrophic gram-positives do, they are the smallest cells known to man and they are the only bacteria that do not have cell walls. They are not actually gram-positive, but they are very closely related to some species that are, so they are classified as gram-positive. They are commonly found in soil and some are harmful to animals causing walking pneumonia in some cases. ---c.Actinomycetes: These are a type of gram-positive bacteria that form large colonies similar to fungi. Some are used in the production of commercial antibiotics. 3. Cyanobacteria: These are generally photoautotrophs that use photosynthesis as a source of energy. They have chlorophyll a, the type of chlorophyll plants have, and they produce oxygen as a byproduct as do most plants. They usually live in water, both fresh and salt, or symbiotically with fungi such as lichens. They perform a variety of functions such as nitrogen fixation, and they have thick gel-like cell walls. They move by gliding, not by using flagella. These bacteria can take on single celled forms, colonies, or multicellular "organisms" that have specialized areas for performing specialized tasks. 4. Spirochetes: These are chemoheterotrophs, and they are very long and thin. They have fillaments that act as flagella to propel these strand-like cells into helical, corkscrew shapes. Many of these species are pathogenic, or harmful. Different species of these bacteria are responsible for causing Syphilis, and Lyme disease. 5. Chlamydias: These are parasitic bacteria and the get all of their energy from their hosts. They have gram-negative cell walls and do not have peptidoglycan which most bacteria have. Species of chlymydias are respoinsible for causing most cases of blindness and the STD nongonococcal urethritis. The next Domain, Domain Archea consists of the oldest and most primitive bacterium that we know of. They have many differences from Eubacteria which prompts some scientists to place them in their own kingdom. There are three main subdivisions of Archeabacteria. They are: 1.Methanogens, archeabacteria that produce methane. They cannot tolerate exposure to air, and they can use Carbon dioxide as a carbon source for energy. They are commonly found in the stomachs of cows, this is why cow manure often releases methane gas. 2.Extreme Halophiles, Archeabacteria that can live in very high concentrations of salt. They are heterotrophs and require high salt concentrations for growth. They live in salty areas such as salt lakes and the dead sea. 3.Extreme Thermophiles, Archeabacteria that can live at very high temperatures. They require lots of heat for growth, and their membranes and enzymes are stable at high temperatures. They often also require sulfur for growth. Some species even oxidize sulfur for energy. Now that you know about bacteria, play games with creatures that look like bacteria! Bacteria shapes are seen in both the blobs game, and the frendz game. The blobs resemble clusters of cocci, the sphere-like bacteria. Or if you don't fancy Blobs, how about Frendz? These creatures also look like cocci! They also can change colors from red to blue, and the blue would then slightly resemble cyanobacteria! Have fun, and remember, everything is biology! BACTERIA WORDSEARCH!!!!!! See how many bacteria-related words from our site you can find in here!