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BACTERIA

BACTERIA. Prokaryotes are single-celled organisms that do not have a membrane-bound nucleus. Prokaryotes are the MOST NUMEROUS ORGANISMS ON EARTH.

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BACTERIA

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  1. BACTERIA • Prokaryotes are single-celled organisms that do not have a membrane-bound nucleus. • Prokaryotes are the MOST NUMEROUS ORGANISMS ON EARTH. • Prokaryotes 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. • Evidence in the fossil record indicates that Prokaryotes are about 2.5 Billion Years Old and Modern Humans arose about 100,000 years ago. • It wasn't until the late 1600s that scientists discovered bacteria.  In fact, bacteria were discovered by accident. • Anton van Leeuwenhoek accidentally noticed them while looking at scrapings from his teeth through a very simple microscope.  He did not know what they were, but he was essentially the first person to see bacteria. • Organisms are classified as Prokaryotes by ONE CHARACTERISTIC: THE LACK OF A CELL NUCLEUS. • Contains two kingdoms.

  2. Kingdom Archaebacteria 1 THE ARCHAEBACTERIA ARE A GROUP OF Prokaryotes THAT LIVE IN UNUSUALLY HARSH ENVIRONMENTS. 2. Scientists treat Archaebacteria as a separate Kingdom because these organisms are So Different from other Prokaryotes. 3. Archaebacteria are CHEMICALLY DISTINCT from other Prokaryotes 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.

  3. Kingdom Archeabacteria • 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.

  4. 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; round, rod, and spiral shaped. 4. We will be studying many different types of these kinds of bacteria.

  5. General Structure of Bacteria

  6. General Structure of Bacteria 1. Nucleoid: The nucleoid is a region of cytoplasm where the chromosomal DNA is located. It is not a membrane bound nucleus, but simply an area of the cytoplasm where the strands of DNA are found. Most bacteria have a single, circular chromosome that is responsible for replication, although a few species do have two or more. Smaller circular auxiliary DNA strands, called plasmids, are also found in the cytoplasm 2. Cytoplasm - The cytoplasm, or protoplasm, of bacterial cells is where the functions for cell growth, metabolism, and replication are carried out 3. Capsule - Some species of bacteria have a third protective covering, a capsule made up of polysaccharides (complex carbohydrates). Capsules play a number of roles, but the most important are to keep the bacterium from drying out and to protect it from phagocytosis (engulfing) by larger microorganisms. The capsule is a major virulence factor in the major disease-causing bacteria, such as Escherichia coli and Streptococcus pneumoniae. Nonencapsulated mutants of these organisms are avirulent, i.e. they don't cause disease. 4. Flagella - Flagella (singular, flagellum) are hairlike structures that provide a means of locomotion for those bacteria that have them.

  7. General Structure of Bacteria 5. Pili - Many species of bacteria have pili (singular, pilus), small hairlike projections emerging from the outside cell surface. These outgrowths assist the bacteria in attaching to other cells and surfaces, such as teeth, intestines, and rocks. Without pili, many disease-causing bacteria lose their ability to infect because they're unable to attach to host tissue. 6. Ribosomes- the building blocks of proteins. Proteins are the molecules that perform all the functions of cells and living organisms 7. Cell Wall - Each bacterium is enclosed by a rigid cell wall composed of peptidoglycan, a protein-sugar (polysaccharide) molecule. The wall gives the cell its shape and surrounds the cytoplasmic membrane, protecting it from its environment. 8. Cytoplasmic Membrane - A layer of phospholipids and proteins, called the cytoplasmic membrane, encloses the interior of the bacterium, regulating the flow of materials in and out of the cell. This is a structural trait bacteria share with all other living cells; a barrier that allows them to selectively interact with their environment. (this is also called cell membrane)

  8. Shapes of Bacteria (Eubacteria only) Three Shapes: 1. Spirochetea/Spirilla: Spiral Shaped - This type of bacteria is generally responsible for diseases such as cholera ( Vibrio cholerae ), and are generally found in stagnant water, and water which has been contaminated with sewage (this actually looks like a curved rod). - Basically a corkscrew shaped bacterium. It causes diseases such as lyme disease (Borreliaburgdorferi ).

  9. Shapes of Bacteria (Eubacteria) 2. Bacillus or Rod-shaped - The second and slightly more complex type of bacteria are the genus Bacillus. These bacteria are rod shaped, and can be very short or very long. Most bacilli are capable of forming spores, which can protect the bacteria from harsh conditions such as dryness etc, and the bacteria within can remain viable for up to 100 years. - Bacilli are also capable of causing many diseases, such as Yersinia pestis, which causes bubonic, pneumonic and sceptacaemic plague, and Bacillus anthracis, which causes the, by now probably very famous disease, due to the post 9/11 attacks, anthrax. Common types of bacillus are Lactobacillusspp which generally cause milk to spoil, and a number of various soil dwelling species. Salmonella typhi

  10. Shapes of Bacteria (Eubacteria) 3. Cocci or round shaped: - These bacteria are generally some of the smallest, and simplest, being small and spherical, hence Cocci (berry shaped). - There are a number of bacteria in this category which are pathogenic (disease causing) such as Staphlycoccusaureus , which causes a type of food poisoning, and is rapidly becoming known as the hospital superbug, a variant of this species called MRSA (Methicillin Resistant Staphylococcus aureus ), N. meningitidis, which causes the often deadly diseases, meningitis, Staphylococcus epidermis which inhabits the skin and can cause spots and boils, and finally Moraxella catarrhalis, which generally tends to cause infections in the lower respiratory tract in humans. pair of Cocci Staphylococcus aureus

  11. Bacteria exists in groups and colonies A. Strepto: chains of bacteria Streptococcus

  12. Groups of Bacteria B. Staphylo: Clusters Staphylococcus

  13. Groupings of bacteria C. Diplo: two Diplococcus

  14. Bacterial groups D. Tetra: Four A tetrad appears as a square of four cocci (arrows). Tetracoccus

  15. Gram Staining Most species of bacteria can be grouped into TWO Categories based on their response to a laboratory technique called GRAM STAINING. (Figure 23-4) 1. TAXONOMISTS divide bacteria into various subgroups including GRAM-POSITIVE AND GRAM-NEGATIVE BACTERIA. 2. Hans Christian Gram, a Danish Microbiologist, developed the Gram-stain technique in 1884 3. The technique involves STAINING Bacteria with a PURPLE DYE (Crystal Violet), AND IODINE,   AND RINSED WITH ALCOHOL.  Then Restained with A PINK DYE (Safarinin). (Figure 24-3) 4. Depending on Structure of their CELL WALLS, THE BACTERIA ABSORB EITHER THE PURPLE DYE OR THE PINK DYE.   5.  Gram-Positive Bacteria will retain the PURPLE DYE and appear Purple. 6.  Gram-Negative Bacteria will appear PINK from the PINK DYE.

  16. Gram Positive Bacteria: antibiotics can work • 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.

  17. Gram-negative bacteria: antibiotics cannot work • 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.

  18. Bacterial Reproduction • Bacteria can reproduce at tremendous speeds.  Some bacteria can reproduce as often as once every 20 minutes!  However, bacteria have to have certain conditions in which to reproduce.  These conditions are not often met, and that is one thing that keeps bacteria from growing out of control. • Bacteria reproduce using two basic methods:  asexual reproduction and sexual reproduction. • Asexual reproduction involves only one individual or parent.  The offspring generated by asexual reproduction are exact duplicates of the parent.  Binary fission is the process by which a bacteria splits into two cells.  Each cell gets an exact copy of the parent cell's genetic material. Binary Fission

  19. Reproduction Sexual reproduction involves the joining of two parent cells and the exchanging of genetic materials.  In sexual reproduction, the offspring will have a mixture of the parent cells' traits.  Conjugation is the process by which bacteria join and exchange genetic materials.  Once genetic materials are exchanged, each bacteria cell will go through binary fission to produce an offspring with a new genetic makeup.

  20. Additional Vocabulary • Aerobic: needs oxygen • Anaerobic: without oxygen • Faculatice Anaerobic: with or without oxygen • Autotrophs: Make own food a. Photoautotroph: Use sunlight to make food b. Chemoautotrophs: Use energy of chemical reactions for food • Heterotrophs: Get food from another source a. Saprophyte: feeds on dead decaying matter

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