BACTERIA EVOLUTION AND CLASSIFICATION

Bacteria are the most numerous organisms of Earth as well as the most ancient - they were probably the first forms of life.  It is likely that all other organisms evolved from bacteria.  The earliest fossils show that bacteria existed long before other forms of life evolved.

OBJECTIVES:  Define bacteria, eubacteria, and archaebacteria, and note the relationships between them.  Describe the methods used to classify bacteria.  Name and describe three known types of archaebacteria.  Distinguish Gram-positive bacteria from Gram-negative bacteria.  Describe the significance of cyanobacteria in the formation of the Earth's present atmosphere.

EVOLUTION AND CLASSIFICATION

1. BACTERIA are microscopic Prokaryotes.

2.  Bacteria are the MOST NUMEROUS ORGANISMS ON EARTH.

3.  Bacteria have evolved into many different forms, and they are now part of nearly every environment on Earth.  They have been found at the bottom of the oceanic trenches 9.6 km (6 mi) below the water's surface and in Arctic and Antarctic Regions.

4. Evidence in the fossil record indicates that Prokaryotes are about 2.5 Billion Years Old and Modern Humans arose about 100,000 years ago.

5. Organisms are classified as Bacteria by ONE CHARACTERISTIC: THE LACK OF A CELL NUCLEUS.

6.  Unlike most other organisms, Bacteria have few Morphological differences that can be used to classify them, Bacteria do Not vary in size and shape to the extent that other types of organisms do.

7. Traditionally, bacteria have been grouped based on their Structure, Physiology, Molecular Composition, and Reaction to specific types of stains, (Gram Stain), rather than on their evolutionary relationships.

8. By comparing RIBOSOMAL RNA SEQUENCES, scientists have found that there are TWO Vastly different types of Bacteria:

    A. The Bacteria that we generally refer to as "GERMS" are classified in the KINGDOM EUBACTERIA, or EUBACTERIA, or simpler yet BACTERIA.

    B. The Other Type of bacteria are called ARCHAEBACTERIA, and belong to the KINGDOM ARCHAEBACTERIA.  These are the more ancient bacteria.

9. PROKARYOTES SHARE SEVERAL CHARACTERISTICS:

    A.  PROKARYOTES DO NOT HAVE A MEMBRANE-BOUND NUCLEUS.

    B.  PROKAROYTES DO HAVE A CELL MEMBRANE, BUT DO NOT HAVE MEMBRANE BOUND ORGANELLES.

    C.  PROKARYOTES HAVE RIBOSOMES THAT ARE DIFFERENT FROM THOSE OF EUKARYOTES.

    D.  ALMOST ALL PROKARYOTES ARE SMALLER THAN THE SMALLEST EUKAROYTES.

    E.  MOST PROKARYOTES ARE SINGLE-CELLED ORGANISMS (UNICELLULAR).

KINGDOM ARCHAEBACTERIA

1. THE ARCHAEBACTERIA ARE A GROUP OF BACTERIA THAT LIVE IN UNUSUALLY HARSH ENVIRONMENTS.

2. Scientists treat Archaebacteria as a separate Kingdom because these organisms are So Different from other bacteria.

3. Archaebacteria are CHEMICALLY DISTINCT from other BACTERIA in several ways:

    A.  The Cell Walls, Cell Membranes, and Ribosomal RNA are different from those of other BACTERIA. The Absence of PEPTIDOGLYCAN, a protein-carbohydrate found in the cell walls of Eubacteria.

    B. They can live where no other organism can survive.  They live in extreme environments, such as acidic hot springs, near undersea volcanic vents, and highly salty water.

4. The PREFIX "ARCHEA" means ANCIENT.  They are considered ancient because they probably resemble the FIRST FORMS of LIFE on Earth.

5. Scientist think that the harsh environments in which Archaebacteria now live are like conditions on the Earth when life first appeared and began to evolve.

6. Archaebacteria can be divided into THREE Groups, based on the Environment in which they live:

    A.  METHANOGENS - Live in oxygen-free environments (anaerobic conditions) and produce Methane Gas.   They are named for their unique method of harvesting Energy by converting H2 and CO2 into Methane Gas. Because Oxygen is a Poison To Them, Methanogens can Live Only in ANAEROBIC Conditions, such as the Bottom of Swamps and in Sewage.  The methane produced by methanogens living in the waters of SWAMPS, SEWAGE, or MARSHES is called SWAMP GAS.  Methane produced in the DIGESTIVE TRACTS of many animals including humans is called INTESTINAL GAS.  In the digestive track of cows they break down CELLULOSE, enabling cows to use nutrients in grass and plants.  They are used in INDUSTRY to treat SEWAGE and to help PURIFY WATER.

    B.  THERMOACIDOPHILES - Can live in Water that is Extremely HOT (230 degrees F.) and ACIDIC (pH less than 2), two conditions that would kill other organisms.  Can be found around HOT SPRINGS like those at Yellowstone National Park, No other organism can live in these waters!  Thermoacidophiles live near volcanic vents on land or near hydrothermal vents, cracks in the ocean floor miles below the surface that leak scalding acidic water.

    C.  EXTREME HALOPHILES - Live in Extremely SALTY Conditions.  Found in the Great Salt Lake in Utah and the Dead Sea.  Can grow in water that is up to ten times saltier than seawater. High salt concentrations would kill most bacteria, but this high concentration is beneficial to the growth of Extreme Halophiles, and these organisms use Salt to Generate ATP.

KINGDOM EUBACTERIA

1. Eubacteria account for most bacteria; they occur in many shapes and sizes and have distinct Biochemical and Genetic Characteristics.

2. The PREFIX "EU" means TRUE.  The so-called true bacteria are all the organisms traditionally known as BACTERIA OR AS MOM WOULD SAY "GERMS".

3. Bacteria can be one of THREE Different SHAPES: 

    A.  Eubacteria that are ROD-SHAPED are called BACILLI

    B.  SPHERE-SHAPED Eubacteria are called COCCI.  WHEN COCCI OCCURE IN CHAINS, THEY ARE CALLED STREPTOCOCCI, GRAPELIKE CLUSTERS OF COCCI ARE CALLED STAPHYLOCOCCI.

    C.  SPIRAL-SHAPED EUBACTERIA ARE CALLED SPIRILLA.

BACTERIA USUALLY GAIN PART OF THEIR NAME FROM THEIR SHAPE.

4.  Eubacteria can be divided into as many as 12 different PHYLA according to their Evolutionary Relataionships.  We are going to look at Four Generally Recognized Phyla of Bacteria and their properties, CYANOBACTERIA, SPIROCHETES, GRAM-POSITIVE, PROTEOBACTERIA.

GRAM STAINING

1.  Most species of Eubacteria can be grouped into TWO Categories based on their response to a laboratory technique called GRAM STAINING.

2. TAXONOMISTS divide Eubacteria into various subgroups including GRAM-POSITIVE AND GRAM-NEGATIVE BACTERIA.

3.  THESE ARE TERMS FOR THE WAY BACTERIA RESPOND TO A PROCEDURE CALLED GRAM STAINING.

4. Hans Christian Gram, a Danish Microbiologist, developed the Gram-stain technique in 1884.

5. The technique involves STAINING Bacteria with a PURPLE DYE (Crystal Violet), AND IODINE,   AND RINSED WITH ALCOHOL.  Then Restained with A PINK DYE (Safarinin).

6. Depending on Structure of their CELL WALLS, THE BACTERIA ABSORB EITHER THE PURPLE DYE OR THE PINK DYE.

7.  Gram-Positive Bacteria will retain the PURPLE DYE and appear Purple.

8.  Gram-Negative Bacteria will appear PINK from the PINK DYE.

GRAM POSITIVE BACTERIA

1. GRAM-POSITIVE BACTERIA HAVE A THICKER LAYER OF PEPTIDOGLYCAN IN THEIR CELL WALLS, MADE OF A PROTEIN-SUGAR COMPLEX THAT TAKES ON THE PURPLE COLOR DURING GRAM STAINING.

2. Gram-positive bacteria include organisms that produce BENEFICAL Substances and organisms that cause important DISEASE.

3. They are used to make yogurt, pickles and buttermilk.

4. Another group of Gram-positive bacteria, are used to make ANTIBIOTICS, INCLUDING TETRACYCLINE AND STREPTOMYCIN.  THESE BACTERIA ARE CALLED ACTINOMYCETES.

5. Antibiotics kill other Gram-positive bacteria by preventing them from making proteins.  They affect only the GROWTH of bacteria without harming the body cells of humans.

6. Gram-positive bacteria cause many HUMAN DISEASES, INCLUDING SCARLET FEVER, TOXIC SHOCK SYNDROME, AND PNEUMONIA.

7. Many of these bacteria produce TOXINS, which are poisons to our bodies.

8. Toxins can be deadly; a single gram of the toxin produced by Clostridium botulinum  (Botulism) could kill more than one million people.

GRAM-NEGATIVE BACTERIA

1. GRAM-NEGATIVE BACTERIA HAVE AN EXTRA LAYER OF LIPID ON THE OUTSIDE OF THE CELL WALL AND APPEAR PINK AFTER GRAM STAINING.

2. The extra lipid layer stops the PURPLE Stain from entering the CELL WALL.  They do absorb the PINK Stain, so they are easily distinguished with a microscope.

3. The extra lipid layer also stops many ANTIBIOTICS from entering the bacteria.  Treatment for these requires a different ANTIBIOTIC than those used for infections caused by Gram-positive bacteria.

4. These bacteria may have evolved from a PHOTOSYNTHETIC ancestor.  Some of these bacteria are still photosynthetic, but most are not.

5. These bacteria photosynthesis differ from plants, they do not release oxygen as a by-product, but produce SULFUR as a by-product.

6. Bacteria that produce sulfur are also called SULFUR PRODUCING BACTERIA.

PHYLUM CYANOBACTERIA

1. THE CYANOBACTERIA ARE GRAM-NEGATIVE BACTERIA THAT PERFORM PLANT-LIKE PHOTOSYNTHESIS AND RELEASE OXYGEN AS A BY-PRODUCT (Waste Product).

2. They are much LARGER than many other prokaryotes, and because they produce oxygen and provide food for other organisms they play an important role in many Ecosystems.

3. They were once classified as blue-green Algae, because they grow in long filaments resembling algae, but are now considered eubacteria because they lack a membrane-bound Nucleus and Chloroplasts.

4. They are YELLOW, RED, BROWN, GREEN, AND EVEN BLACK, AS WELL AS BLUE-GREEN.

5. Unlike other Eubacteria, Cyanobacteria are encased in a jelly-like substance and often cling together to form Colonies.

6. Certain Cyanobacteria grow in chains.  Some of these cells form specialized cells called HETEROCYSTS.

7. Heterocysts contain Enzymes for Fixing Atmospheric Nitrogen.  Cyanobacteria that form Heterocysts make Nitrogen Available to plants in a form that plants can use.

8. Certain Cyanobacteria (Anabaena) thrive on Phosphates and Nitrates that accumulate in a body of Water.  The Sudden Increase in the number of Cyanobacteria due to High availability of nutrients is called EUTROPHICATION, OR POPULATION BLOOM.

9. Following Eutrophication, many of the Cyanobacteria DIE and are Decomposed by Heterotrophic Bacteria.  The increasing population of Heterotrophic Bacteria consume available Oxygen in the water, causing other organisms in the water, such as fish, to DIE from Lack of Oxygen.

PHYLUM SPIROCHETES

1. Spirochetes are Gram-Negaitive Bacteria, Spiral-Shaped Heterotrophic Bacteria.

2. Some Spirochetes are Aerobic, and some are Anaerobic.

3. They move by means of a corkscrew-like rotation.

4. Spirochetes live Freely, Symbiotically, or Parasitically.

5. One Well Known Spirochete is Treponema pallidum, which causes the sexually transmitted disease Syphilis.

PHYLUM GRAM-POSITIVE BACTERIA

1. Despite its name, NOT all Members of this phylum are Gram-positive.  A Few species of Gram-negative bacteria are also grouped in this phylum because they share molecular similarities with Gram-positive bacteria.

2. Members of this Phylum include the species of Streptococci that causes Strep Throat.

3. Milk becomes Yogurt when certain Gram-positive Bacilli grow in Milk and produce Lactic Acid.

4. Gram-positive Bacilli are also found in the Oral Cavity and in the intestinal Tract, where they Retard the growth of Disease causing Bacteria.

5. Lactobacilli, Gram-positive Bacilli found on the Teeth, are known to cause Tooth Decay through release of Acid.

6. ACTINOMYCETES are Gram-positive bacteria that form branching filaments.  They grow in the Soil and Produce ANTIBIOTICS, chemicals that Inhibit the Growth of or Kill other Microscopic Organisms.

PHYLUM PROTEOBACTERIA

1. The Proteobacteria make up one of the Largest and Most Diverse phylum among bacteria.

2. This Group is divided into several Subdivisions, including : ENTERIC BACTERIA, CHEMOAUTOTROPHIC BACTERIA, AND NITROGEN-FIXING BACTERIA.

ENTERIC BACTERIA

1. These are Gram-negative Heterotrophic Bacteria that Inhabit Intestinal Tracts and can live in either Aerobic or Anaerobic conditions.

2. This group includes the well known organism Escherichia coli (E. coli).

3. E. coli lives in human intestines where it produces Vitamin K an assists Enzymes in the Breakdown of food.

4. Other Enteric Bacteria are responsible for disease such as Salmonella, responsible for Food Poisoning.

CHEMOAUTOTROPHS

1. Chemoautotrophs are Gram-negative bacteria that can extract Energy from Minerals by Oxidizing the Chemicals in these Minerals.

2. Iron-oxidizing bacteria live in freshwater ponds that contain a high concentration of iron salts.  The iron bacteria oxidize the iron in the salts to obtain energy.

NITROGEN-FIXING BACTERIA

1. Nitrogen-fixing Bacteria, such as RHIZOBIUM are Gram-Negative bacteria that grow Symbiotically in root nodules of such plants as soybean, beans, peas clover, and alfalfa.

2. The Earth's atmosphere is 80% NITROGEN (N2), but plants and animals cannot use nitrogen in its gaseous state.  We depend on Nitrogen-fixing bacteria in plants to convert gaseous nitrogen into compounds such as AMMONIA.

3. We require Nitrogen to make nitrogen-containing compounds like Proteins and Nucleic Acids.

4. No other Kingdom includes organisms that can fix nitrogen. Rhizobium are essential to the NITROGEN CYCLE.  Without them and other nitrogen fixers, the diversity of life on our planet could not exist.

BIOLOGY OF BACTERIA

Viewed through a light microscope, bacteria appear to be relatively simple rods, spheres, and other forms.  However, the electron microscope reveals a great amount of detail structure within each form.  These detailed structures are responsible for the activities carried out by bacteria.

OBJECTIVES:  Describe the structure of a bacterial cell.  Describe three ways that bacteria move.  Compare the heterotrophic modes of nutrition in bacteria with the autotrophic modes.  Discuss the various types environments that bacteria occupy.  List three types of genetic recombination used by bacteria.

STRUCTURE

1. Bacteria are Typically composed of a Cell Wall, a Cell Membrane, and Cytoplasm. 

2. Some bacteria have Distinctive Structures, such as Endospores, Capsules, and Outer Membranes.

3. The Variety of Structures among Bacteria is due to adaptations to individual niches (place in the world).

CELL WALL

1. With few exceptions, both Eubacteria and Archaebacteria have a Cell Wall.

2. Unlike plant cells walls, Eubacteria cell walls are made of PEPTIDOGLYCAN.  Peptidoglycan is composed of short chains of Amino Acids, or Peptides, and Carbohydrates.

3. Archaebacteria cell walls are composed of a different compound.

4. In Gram-negative Eubacteria, the cell wall includes an outer membrane this is composed of a layer of Lipids and Sugars.

5. The outer membrane protects these Bacteria against some kinds of Antibiotics by preventing their entry into the cell.  Many antibiotics have No Effect on Gram-negative Bacteria.

CELL MEMBRANE AND CYTOPLASM

1. The Bacterial Cell Membrane is composed of a Lipid Bilayer similar to Eukaryotes.

2. In Bacteria, the cell membrane contains Enzymes that Perform the Reactions of Cellular Respiration.

3. Bacteria do NOT have Mitochondria so they use their cell membranes to carry out Cellular Respiration.

4. The cell membranes of Photosynthetic Bacteria have internal foldings called THYLAKOIDS, these are equal to the Thylakoids found in Chloroplasts.

5. Bacteria Thylakoids contain Photosynthetic Pigments and carry out the function of Photosynthesis.

6. Bacterial cells do NOT have membrane bound organelles.  The CYTOPLASM of Bacterial cells is made of a Viscous (Thick Liquid) solution of Ribosomes and DNA.

7. The Bacterial DNA is arranged in a single, closed loop.  Some bacteria also have PLASMIDS, self-replicating loops of DNA, in their Cytoplasm.

CAPSULES AND PILI

1. Many bacterial species produce an Outer Covering called a CAPSULE.  The capsule is made of polysaccharides that cling to the surface of the cell and Protect It against drying or harsh chemicals and a host body's white blood cells, which would otherwise engulf (eat) it.

2. When a Capsule consists of a Fuzzy Coat of Sticky Sugars, it is called a GLYCOCALX (GLIE-koh-KAY-liks).  The Glycocalyx enables bacteria to attach to the surface of host cells and tissue.

3. PILI are Short, Hairlike Protein Structures found on the Surface of some species of bacteria.  Pili help bacteria hold on to host cells, and are also used to transfer genetic material from one bacterium to another.

ENDOSPORES

1. Some bacteria have a special means of surviving difficult conditions.  WHEN LIVING CONDITION BECOME UNFAVORABLE, SOME BACTERIA FORM SPECIAL, DEHYDRATED CELLS CALLED ENDOSPORES.

2. A bacterial Endospore is a dormant structure that is produced by some Gram-positive bacterial species that are exposed to harsh environmental conditions.

3. Endospores consists of a Thick Outer Covering that surrounds the Cell's DNA.

4. Although the Original Cell may be Destroyed (Die) by harsh conditions, its Endospore will survive. They help bacteria resist High Temperature, Harsh Chemicals, Radiation, Drying, and other environmental extremes.

5. Bacteria that form Endospores have an advantage for survival.  Endospores can be alive but inactive for many years.

6. When conditions improve (become favorable), they break open and produced new bacteria cells.

7. This is NOT a form of Reproduction (THEY ARE NOT REPRODUCTIVE CELLS), but it does allow some species of bacteria to survive hostile conditions and to grow and reproduce when conditions improve.

MOVEMENT STRUCTURES

1. Many Bacteria use FLAGELLA, WHIPLIKE STRUCTURES, FOR MOVEMENT.  These are usually used to move bacteria cells through water.

2. Bacteria that Lack Flagella have other methods of Movement.

3. Myxobacteria produce a Layer of Slime and then Glide through it.

4. Some Spiral-shaped bacteria move by a Corkscrew-Like Rotation.  These organisms have Flexible Cell Walls and filaments within the Cell Walls that, when Contracted, cause the bacterium to turn and move ahead.

STRUCTURAL CHARACTERISTICS OF A BACTERIAL CELL

NUTRITION AND GROWTH

1. TWO major differences between groups of BACTERIA are their SOURCE OF ENERGY AND WHETHER OR NOT THEY USE OXYGEN FOR CELLULAR RESPIRATION.

2. Most BACTERIA are HETEROTROPHS; they get their energy by consuming Organic Matter as a source of Nutrition.

3. Heterotrophic bacteria that feed on dead or decaying material are called SAPROPHYTES.

4. Some are AUTOTROPHS, they obtain their energy by making their own Food from SUNLIGHT OR MINERALS.

5. PHOTOAUTOTROPHS ARE BACTERIA THAT USE SUNLIGHT AS AN ENERGY SOURCE.

6. CHEMOAUTOTROPHS OBTAIN THEIR FOOD FROM OXIDIZING INORGANIC COMPOUNDS INSTEAD OF SUNLIGHT.

7. The Second important Metabolic difference between BACTERIA groups has to do with CELLULAR RESPIRATION.

8. ORGANISM THAT USE OXYGEN DURING CELLULAR RESPIRATION ARE CALLED AEROBES.

9. THOSE THAT DO NOT USE OXYGEN ARE CALLED ANAEROBES, TYPICALLY THEY GET ENERGY FOR THEIR CELLULAR RESPIRATION THROUGH FERMENTATION.

10. THE PRESENCE OR ABSENCE OF OXYGEN IN THE ENVIRONMENT IS A LIFE DETERMINING CONDITION FOR SOME BACTERIA:

    A. BACTERIA CALLED OBLIGATE AEROBES CANNOT LIVE WITHOUT OXYGEN.

    B. BACTERIA CALLED OBLIGATE ANAEROBES CANNOT LIVE IN THE PRESENCE OF OXYGEN.

    C. BACTERIA CALLED FACULTATIVE ANAEROBES CAN USE OXYGEN WHEN IT IS AVAILABLE, BUT THEY DO NOT DEPEND UPON IT.

11. Bacteria have varying Temperature Requirements for Growth.  Some bacteria grow best in Cold Temperatures of 0-20 degrees C (32-68 F).  Others grow best in Temperatures between 20-40 degrees C (68-104 F).

12. Thermophilic (Heat Loving) bacteria grow best in Temperatures between 40-110 degrees C (104-230 F).

13. Most bacteria Grow BEST at a pH of 6.5 to 7.5 (7.0 is neutral).

REPRODUCTION AND GENETIC RECOMBINATION

1. MOST BACTERIA reproduce by a process called BINARY FISSION.

2. BINARY FISSION IS A PROCESS IN WHICH THE CHROMOSOMES REPLICATE, AFTER WHICH THE CELL DIVIDES.

3. BINARY FISSION IS A TYPE OF ASEXUAL REPRODUCTION.

4. Under ideal conditions, bacteria divide (reproduce) rapidly, DOUBLING THEIR NUMBERS EVERY 20 MINUTES.

5. ALL BACTERIA ARE HAPLOID AND CONTAIN ABOUT 1/1000 AS MUCH DNA AS ORDINARY EUKARYOTIC CELLS.  MOST BACTERIA'S DNA IS A SINGLE DOUBLE STRAND THAT ATTACHES TO THE CELL MEMBRANE AND REPLICATES JUST BEFORE THE CELL DIVIDES.

6. Some kinds of bacteria also contain SMALLER PIECES OF CIRCULLAR DNA CALLED PLASMIDS.  PLASMIDS are used in genetic engineering to carry new genes into other organisms.

7. BACTERIA CAN EXCHANGE GENES BY ONE OF THREE SPECIAL MEANS: CONJUGATION, TRANSFORMATION, OR TRANSDUCTION.

    A. CONJUGATION - THE PROCESS OF EXCHANGING GENETIC MATERIAL THROUGH CELL-TO-CELL CONTACT (Conjugation bridge). During conjugation, DNA Moves from one bacteria cell to another, this allows the DNA to change and provide VARIATIONS and DIVERSITY of the generations of bacteria to follow.  It Increases the chances that some bacteria will survive the environment changes. The bacteria attached together using special hairlike structures called PILI, a bridge of cytoplasm (CONJUGATION BRIDGE) forms between two bacteria cells, and the DNA passes from one cell to another.

    B. TRANSFORMATION - THE PROCESS BY WHICH BACTERIA CELLS PICK UP AND INCORPORATE DNA FROM DEAD BACTERIA CELLS.  THEY TAKE UP DNA FROM DEAD CELLS OF THE SAME OR A CLOSELY RELATED SPECIES.

    C. TRANSDUCTION - USING A VIRUS TO TRANSFER DNA FROM ONE BACTERIA TO ANOTHER.  VIRUSES CALLED BACTERIAPHAGES ARE USED TO CARRY DNA BETWEEN CELLS.  THIS IS ONE WAY TO GET BACTERIA TO MAKE LARGE AMOUNTS OF PROTEINS FOR RESEARCH AND MEDICINE.  THIS IS USED TO PRODUCE HUMAN INSULIN NEED BY DIABETICS.

8. GENETIC RECOMBINATION in Bacteria is a NONREPRODUCTIVE means by which bacteria acquire new combinations of genes.

BACTERIA AND HUMANS

Much of our knowledge about bacteria is a result of the study of the diseases they cause in humans.  In addition to what we have learned about pathogenic bacteria and how they cause disease, we have also learned how bacteria benefit us.  Bacteria are used in food preparation and in environmental, chemical and mining processes.

OBJECTIVES:  Describe the ways that bacteria can cause disease in humans.  Specify how antibiotic resistance has come about, and describe ways that bacteria resist antibiotics.  List three ways that bacteria are helpful to humans.

BACTERIA AND DISEASE

1. Many of us only think of bacteria as the germs that cause DISEASE. The scientific study of disease is called PATHOLOGY.  Bacteria that cause disease are called PATHOGENS. (BACTERIAL DISEASES)

2. Some bacteria cause Disease by Producing Poisons called TOXINS.

3. EXOTOXINS are Toxins that are made from Protein. Exotoxins are produced by Gram-positive Bacteria and are secreted into the surrounding environment.  TETANUS is a disease caused by an Exotoxin. Ever cut yourself or step on a nail and had to take a shot?  That was to prevent Tetanus.

4. ENDOTOXINS are Toxins made of Lipids and Carbohydrates, are associated with the outer membrane of Gram-negative bacteria, such as E. coli.  Endotoxins are Not Released until the bacteria Dies.  Endotoxins cause fever, body aches, and weakness, and they damage the vessels of the Circulatory System.

5. Bacteria can also cause disease by damaging and destroying body tissue (Streptococci). As bacteria adhere to cells, they secrete digestive enzymes that allow further tissue invasion.

ANTIBIOTICS

1. Antibiotics are Drugs that Fight Bacteria by interfering with their Cellular Functions.

2. PENICILLIN interferes with Cell Wall Synthesis.

3. TETRACYCLINE interferes with Protein Synthesis.

4. Many Antibiotics are derived from chemicals that Bacteria or Fungi Produce.

5. SULFA DRUGS are Antibiotics that are Synthesized in Laboratories. (Man Made)

6. Many Antibiotics are able to affect a Wide Variety of Organisms, they are called BROAD SPECTRUM ANTIBIOTICS.

ANTIBIOTIC RESISTANCE

1. When a population of bacteria is exposed to an Antibiotic, the Most susceptible DIE.  A Few Mutant bacteria that are resistant to the Antibiotic may continue to grow.

2. A Resistant Population then grows from these Mutant Bacteria through reproduction and genetic recombination.

3. These new Population are Antibiotic-Resistant.  This has resulted from the Over Use of Antibiotics.  Many diseases that were once easy to treat are becoming more difficult to treat.

USEFUL BACTERIA

1. Bacteria affect our lives in many positive ways.

2. Bacteria are used in Sewage Treatment, and as Decomposers, breaking down the remains of organic matter in dead plant and animal waste.  Recyclers, returning nutrients back to the environment.

3. Bacteria are useful in food production.  Bacteria help us make buttermilk, sour cream, yogurt, cottage cheese, sauerkraut and pickles.

4. Bacteria are also used in industrial chemical production.  They produce organic chemicals and fuels. Used in the mining of minerals. And  there products are used as insecticides.

5. Bacteria are used to help clean up environmental disasters caused by humans, such as chemical and oil spills.