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Bacteria Prokaryotes Unicellular, organisms that lack a nucleus
Prokaryotes Unicellular, organisms that lack a nucleus Much smaller than most eukaryotic cells
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Kingdoms Eubacteria Archaebacteria now referred to as just Archaea
FYI: The three Domain system, previously discussed was started in the late 1970’s by a scientist by the name of Dr. Carl Woese. His discovery of Archae bacteria (and how different they were from eubacteria, lead him to introduce this change) FYI: Because archaebacteria are so different from eubacteria some scientists do not refer to them as bacteria at all and instead just call them Archaea
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Live almost everywhere
Eubacteria Larger of the two Live almost everywhere Water, land, and within the human body E. coli Anabaena Streptomyces griseus Soil bacteria
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Cell-Surface Structures
One of the most important features of nearly all prokaryotic cells is their cell wall. Functions Maintains cell shape Provides protection Prevents cell from bursting in hypotonic environment
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Within the cell wall is a cell membrane
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HONORS External structures - Peptidoglycan
Carbohydrate in the cell wall of eubacteria only. peptidoglycan Plasma membrane Some eubacteria have a second membrane outside the cell membrane
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Archaea – survive in extreme environments
Their membrane lipids are different from those of eubacteria They lack peptidoglycan They look very similar to eubacteria Thermoacidophiles Morning Glory Pool – Yellowstone 230 degrees farenheit Figure 27.1
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Significance of DNA sequences of key archaea genes
They are more like those of eukaryotes than those of eubacteria Scientists reason that archaea may be the ancestors of eukaryotes
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Example of Archaea Extreme halophiles Live in high saline environments
Figure 27.14
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Example of Archaea Methanogens Produce methane as a waste product
Live in oxygen free environments, such as thick mud and the digestive tracts of animals. Bacteria in digestive tract
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Archaea Bill Nye greatest discoveries (Dr. Woese Archaea) 6:11-9:34 DeGrasse Tyson on Nova 8:52-14:00 AND 32:08-35:56
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Four Characteristics Used to identify Prokaryotes
Shape Chemical nature of cell wall Way they move (motility) Way they obtain energy
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The shapes of Prokaryotes
Prokaryotic cells have a variety of shapes Rod – called bacilli Spherical – called cocci Corkscrew – called spiral 1 m 2 m 5 m (a) Spherical (cocci) (b) Rod-shaped (bacilli) (c) Spiral Figure 27.2a–c
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Motility Most motile bacteria propel themselves by flagella
Which are structurally and functionally different from eukaryotic flagella Some do not move at all Flagellum Filament Hook Cell wall Plasma membrane Basal apparatus 50 nm Figure 27.6
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Metabolic Diversity (modes of nutrition)
Photoautotroph – carries out photosynthesis (light and inorganic molecules) like plants Chemoautotroph – energy from chemical reactions involving inorganic molecules (sulfur, iron,) Heterotroph – take in organic molecules and breaks them down Photoheterotroph- captures sunlight for energy and also needs organic molecules as a carbon source
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Photoautotroph The cyanobacterium
contain a bluish pigment and chlorophyll a Photosynthetic cells The cells exchange, nitrogen for carbohydrates Heterocyst 20 m Heterocysts perform nitrogen fixation – convert nitrogen from atmosphere into ammonia Figure 27.10
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Chemoautotrophs Live near hydrothermal vents Obtain energy from hydrogen sulfide gas that flows from the vents
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The way Prokaryotes release energy. Oxygen requirements
Obligate aerobes Require a constant supply of oxygen Obligate anaerobes Must live in the absence of oxygen Are poisoned by oxygen Facultative anaerobes Can survive with or without oxygen Switch between cellular respiration and fermentation Prokaryotes do not have mitochondria for cellular respiration. Their cellular respiration takes place within the cytoplasm and cell membrane.
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Growth and Reproduction
Prokaryotes reproduce quickly by binary fission A form of asexual reproduction A cell grows to nearly double its size Replicates its DNA Divides in half producing two identical “daughter” cells Can divide every 1–3 hours Some can reproduce every 20 min. How do they stay in control? Use up food supply, poison themselves with waste, consumed by other organisms
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Binary Fission – most bacteria reproduce this way.
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A bacterial mating process
Conjugation A bacterial mating process A hollow bridge forms between two cell and genes move from one cell to another. Transfer takes place through sex pili
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What most bacteria need to live.
Moisture A certain temperature Nutrition darkness
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adaptation Many prokaryotes form endospores – an internal wall that encloses DNA and cytoplasm. Which can remain viable in harsh conditions for centuries When conditions are favorable again, it absorbs water and resumes growth Endospore 0.3 m Figure 27.9 Boiling doesn’t kill endospores. Autoclaving does. (High tem. And pressure.)
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Importance of Bacteria
Decomposers Attack and digest dead tissue Break it down into simpler material This material is released into the soil Without decomposers life would not continue
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Prokaryotes can metabolize nitrogen
Nitrogen Metabolism Prokaryotes can metabolize nitrogen Plants and animals need nitrogen to make amino acids, which help build proteins. Nitrogen fixation Some prokaryotes convert atmospheric nitrogen to ammonia, which is the form that plants can use. Plants use the nitrogen to build amino acids
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Nitrogen Fixation
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Symbiotic Relationships
Many prokaryotes Live with other organisms in symbiotic relationships such as mutualism and commensalisms Figure 27.15
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Prokaryotes are the principal agents in bioremediation
Uses in technology Prokaryotes are the principal agents in bioremediation The use of organisms to remove pollutants from the environment Figure 27.17 Digest petroleum
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Bacteria adapted to extreme environments
May be a rich source of heat-stable enzymes. Can be used In medicine Food production And industrial chemistry
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Some bacteria are pathogens
A pathogen is a disease-causing agent
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How can bacteria cause disease?
Some damage the tissues of the infected organism directly by breaking them down for food. For example, the bacteria that cause tuberculosis break down lung tissue Others release toxins that harm the body
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Bacterial diseases. Prokaryotes cause about half of all human diseases
Examples Lyme disease Tetanus Syphilis Gonorrhea Tuberculosis (TB) Legionnaire's disease Anthrax Meningitis Pertussis Escherichia coli and Salmonella Food poisoining 5 most common bacterial diseases seen around the world
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You Tube 16 worst Bacteria Ever!
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Controlling bacteria Antibiotics
Compounds that block the growth and reproduction of bacteria Our life expectancy has increased due to an increased understanding of how to prevent and cure bacterial infections.
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Antibiotics Cipro Amoxicillin Z pack
Some inhibit the enzymes that allow DNA replication Some inhibit the synthesis of the cell wall Some inhibit protein synthesis Cipro Amoxicillin Z pack
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Vaccinations - Usually a shot that contains some of the bacteria to build up ones immunity
Examples Children and Teens Chickenpox (Varicella) Diphtheria Flu (Influenza) Hepatitis A Hepatitis B Hib Measles Mumps Polio Pneumococcal Rotavirus Rubella Tetanus Whooping Cough (Pertussis) Additional forTeens Only human papillomavirus (HPV) meningococcal disease
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Controlling Bacteria Sterilization – destroying bacteria by subjecting them to either great heat or chemical action
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Controlling Bacteria - Chemical Action
Antiseptics-kill bacteria on living things. -alcohol, hydrogen peroxide, iodine Other (not an antiseptic) soap, toothpaste, mouthwash Disinfectants-kill bacteria on non-living things -Mr. Clean, bleach
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Controlling Bacteria - Heat Killing
Dry heat Open flame Moist heat Autoclave 15 lb/in2 at 121 degree Celsius Pasteurization Heating (kills, does not sterilize)
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Other means of Controlling Bacteria
Refrigeration/Freezing Drying Freeze drying For long term storage All these examples inhibit bacterial growth
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Controlling Bacteria - Change the pH
Usually when dealing with food More acidic Mustard, and tomato products have a higher acid content and therefore, help prevent bacterial growth.
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Other means of controlling bacteria
Radiation UV light Filtration
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Used in the production of a variety of foods
Human Uses of Bacteria Used in the production of a variety of foods Cheese, yogurt, buttermilk, and sour cream. Pickles, sauerkraut
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Human uses of bacteria (they’re not all bad)
Experiments using prokaryotes Have led to important advances in DNA technology
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Human Uses Experiments using prokaryotes
Have led to important advances in DNA technology Genetic Engineering Ex. Cloning Used in industry Oil eating bacteria
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Prokaryotes are also major tools in
Useful Prokaryotes are also major tools in Mining The synthesis of vitamins Production of antibiotics, hormones, and other products Poor quality copper ore, which is bound up in a sulfide matrix, is dumped outside a mine and treated with sulfuric acid to encourage the growth of T. ferooxidans. As the bacteria chew up the ore, copper is released and collected in solution. The sulfuric acid is recycled. Microbes may be used to elaborate precursors in the making of Vitamins A, C, and the B family. Using sugarbeet molasses as a growth medium, Pseudomonas denitrificans is made to produce Vitamin B12. Members of the genus Propionibacterium are also used to make this vitamin.
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Useful Bacteria Used in sewage treatment
Live in the intestine of animals Help digest food. Research suggests that the relationship between gut flora and humans is not merely commensal (a non-harmful coexistence), but rather a symbiotic relationship.[3] Though people can survive without gut flora,[4] the microorganisms perform a host of useful functions, such as fermenting unused energy substrates, training the immune system, preventing growth of harmful, pathogenic bacteria,[2] regulating the development of the gut, producing vitamins for the host (such as biotin and vitamin K), and producing hormones to direct the host to store fats. Bacteria make up most of the flora in the colon[7] and up to 60% of the dry mass of feces.[2] Somewhere between 300[2] and 1000 different species live in the gut,[3] with most estimates at about 500.[4][5][8] However, it is probable that 99% of the bacteria come from about 30 or 40 species.[9
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