• Overview: They’re (Almost) Everywhere!
• Most prokaryotes are microscopic
– But what they lack in size they more than make up for in numbers
• The number of prokaryotes in a single handful of fertile soil
– Is greater than the number of people who have ever lived
 
• Prokaryotes thrive almost everywhere
– Including places too acidic, too salty, too cold, or too hot for most other organisms
 
• Biologists are discovering
– That these organisms have an astonishing genetic diversity
 
• : Structural, functional, and genetic adaptations contribute to prokaryotic success
• Most prokaryotes are unicellular
– Although some species form colonies
Bacterial Structures
• Flagella
• Pili
• Capsule
• Plasma Membrane
• Cytoplasm
• Cell Wall
• Lipopolysaccharides
• Teichoic Acids
• Inclusions
• Spores
 
• Prokaryotic cells have a variety of shapes
– The three most common of which are spheres (cocci), rods (bacilli), and spirals
Shapes of Bacteria
• Coccus
– Chain = Streptoccus
– Cluster = Staphylococcus
• Bacillus
– Chain = Streptobacillus
• Coccobacillus
• Vibrio = curved
• Spirillum
• Spirochete
• Square
• Star
Kingdom Archaebactreria & Eubacteria formally (Prokaryota & Monera)
Bacteria
Prokaryotes = no membrane bound organelles (no nucleus or mitochondria)
 
 
 
Kingdom Monera: The Prokaryotes
V. The 4 main functions of bacteria
Nitrogen fixation
Recycling of nutrients
Food & medicines
Bacteria cause diseases
Nitrogen wastes are excreted & cycled by bacteria
Making cheese & yogurt with bacteria
Strep bacteria of Rheumatic Fever
 
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The Monerans are the most numerous and widespread organisms on earth. They comprise the only kingdom of prokaryotic organisms, those which lack a nucleus or other membrane-bounded organelles.
 
 
External to the plasma membrane, most bacteria have a cell wall partially composed of peptidoglycan, a complex structural molecule not found in eukaryotic cells. Let's have a look at the basic flavors of bacteria .
 
ARCHAEBACTERIA
There are three types of archaebacteria, the most ancient of all living things. The thermoacidophiles live in the extremely hot, acidic water and moist areas within and surrounding sulfur hot springs. So closely adapted are they to their bubbly environment that they die of cold at temperatures of 55oC (131oF)!
 
. Methanogens are obligate anaerobes (free oxygen kills them) which oxidize CO2 during cellular respiration to produce methane (CH4) as a waste product. Although RNA sequencing suggests that all ten known species are evolutionarily related, they exist in environments as diverse as scalding volcanic deep-sea vents and the intestines of mammals.
 
 
The reason you can light a puff of flatulence (should you choose to go into show business) is because of the symbiotic methanogens inside your guts. .
 
 
. Strict halophiles live in extremely salty solutions such as the Dead Sea, the Great Salt Lake and that can of pickled herring you left open in the cupboard. Their pink carotenoid pigments make them conspicuous when the bacteria are present in large concentrations, as they are on the shores of some salty, land-locked lakes. .
Cell-Surface Structures
• One of the most important features of nearly all prokaryotic cells
– Is their cell wall, which maintains cell shape, provides physical protection, and prevents the cell from bursting in a hypotonic environment
 
• Using a technique called the Gram stain
– Scientists can classify many bacterial species into two groups based on cell wall composition, Gram-positive and Gram-negative
 
 
 
 
• The cell wall of many prokaryotes
– Is covered by a capsule, a sticky layer of polysaccharide or protein
 
• Some prokaryotes have fimbriae and pili
– Which allow them to stick to their substrate or other individuals in a colony
Motility
• Most motile bacteria propel themselves by flagella
– Which are structurally and functionally different from eukaryotic flagella
 
• In a heterogeneous environment, many bacteria exhibit taxis
– The ability to move toward or away from certain stimuli
Internal and Genomic Organization
• Prokaryotic cells
– Usually lack complex compartmentalization
 
• Some prokaryotes
– Do have specialized membranes that perform metabolic functions
 
• The typical prokaryotic genome
– Is a ring of DNA that is not surrounded by a membrane and that is located in a nucleoid region
 
• Some species of bacteria
– Also have smaller rings of DNA called plasmids
Reproduction and Adaptation
• Prokaryotes reproduce quickly by binary fission
– And can divide every 1–3 hours
 
• Many prokaryotes form endospores
– Which can remain viable in harsh conditions for centuries
IV 6. Endospores
• Dormant state
• No reproduction
• Metabolic activity is shut down
• Protects bacteria against hostile environments
• “Come back to life” when favorable
Endospores
• Resistant structure
– Heat, irradiation, cold
– Boiling >1 hr still viable
• Takes time and energy to make spores
• Location important in classification
– Central, Subterminal, Terminal
• Bacillus stearothermophilus -spores
– Used for quality control of heat sterilization equipment
• Bacillus anthracis - spores
– Used in biological warfare
 
 
Many organisms form spores:
 
• Rapid reproduction and horizontal gene transfer
– Facilitate the evolution of prokaryotes to changing environments
 
• : A great diversity of nutritional and metabolic adaptations have evolved in prokaryotes
• Examples of all four models of nutrition are found among prokaryotes
– Photoautotrophy
– Chemoautotrophy
– Photoheterotrophy
– Chemoheterotrophy
 
• Major nutritional modes in prokaryotes
Metabolic Relationships to Oxygen
• Prokaryotic metabolism
– Also varies with respect to oxygen
 
• Obligate aerobes
– Require oxygen
• Facultative anaerobes
– Can survive with or without oxygen
• Obligate anaerobes
– Are poisoned by oxygen
Nitrogen Metabolism
• Prokaryotes can metabolize nitrogen
– In a variety of ways
• In a process called nitrogen fixation
– Some prokaryotes convert atmospheric nitrogen to ammonia
Metabolic Cooperation
• Cooperation between prokaryotes
– Allows them to use environmental resources they could not use as individual cells
 
• In the cyanobacterium Anabaena
– Photosynthetic cells and nitrogen-fixing cells exchange metabolic products
 
• In some prokaryotic species
– Metabolic cooperation occurs in surface-coating colonies called biofilms
 
• : Molecular systematics is illuminating prokaryotic phylogeny
• Until the late 20th century
– Systematists based prokaryotic taxonomy on phenotypic criteria
• Applying molecular systematics to the investigation of prokaryotic phylogeny
– Has produced dramatic results
Lessons from Molecular Systematics
• Molecular systematics
– Is leading to a phylogenetic classification of prokaryotes
– Is allowing systematists to identify major new clades
 
• A tentative phylogeny of some of the major taxa of prokaryotes based on molecular systematics
Bacteria
• Diverse nutritional types
– Are scattered among the major groups of bacteria
• The two largest groups are
– The proteobacteria and the Gram-positive bacteria
 
• Proteobacteria
 
• Chlamydias, spirochetes, Gram-positive bacteria, and cyanobacteria
Archaea
• Archaea share certain traits with bacteria
– And other traits
with eukaryotes
Cellular Tree of Life
 
• Some archaea
– Live in extreme environments
• Extreme thermophiles
– Thrive in very hot environments
 
• Extreme halophiles
– Live in high saline environments
 
• Methanogens
– Live in swamps and marshes
– Produce methane as a waste product
 
• : Prokaryotes play crucial roles in the biosphere
• Prokaryotes are so important to the biosphere that if they were to disappear
– The prospects for any other life surviving would be dim
Chemical Recycling
• Prokaryotes play a major role
– In the continual recycling of chemical elements between the living and nonliving components of the environment in ecosystems
 
• Chemoheterotrophic prokaryotes function as decomposers
– Breaking down corpses, dead vegetation, and waste products
• Nitrogen-fixing prokaryotes
– Add usable nitrogen to the environment
Symbiotic Relationships
• Many prokaryotes
– Live with other organisms in symbiotic relationships such as mutualism and commensalism
 
• Other types of prokaryotes
– Live inside hosts as parasites
 
• : Prokaryotes have both harmful and beneficial impacts on humans
• Some prokaryotes are human pathogens
– But many others have positive interactions with humans
Pathogenic Prokaryotes
• Prokaryotes cause about half of all human diseases
– Lyme disease is an example
 
• Pathogenic prokaryotes typically cause disease
– By releasing exotoxins or endotoxins
• Many pathogenic bacteria
– Are potential weapons of bioterrorism
Prokaryotes in Research and Technology
• Experiments using prokaryotes
– Have led to important advances in DNA technology
 
• Prokaryotes are the principal agents in bioremediation
– The use of organisms to remove pollutants from the environment
 
• Prokaryotes are also major tools in
– Mining
– The synthesis of vitamins
– Production of antibiotics, hormones, and other products
6 Major Kingdoms:
• Archaebacteria
• Eubacteria
•Protista
•Fungi
•Planta
•Animalia
• 1 cell, prokaryotes
 
• 1 cell, eukaryotes & algae
• Multicelled, absorptive feeders
• Muticelled, autotrophs
• Muticelled heterotrophs
C. Three major differences between the 2 bacteria Kingdoms:
(All are prokaryotes & One celled, Ubiquitous = found everywhere)
• Many biochemical differences
• Difference cell walls and lipid membranes
• Structure & functions of the of the archaebacteria are more similar to the Eukaryotes
Bacteria Kingdom Characteristics:
Archaebacteria
• Extremists
• No free oxygen
• Methane producers
• Saline habitats
• Hot sulfur springs
Eubacteria
• Heterotrophs
• Parasites
• Saprobes
• Nitrogen decomp.
• Phtotosynthetic autotrophs
• Cyno-blue green
• Chemosynthetic
IV 1.Penicillin
Penicillin mold kills bacteria
• “Antibiotic”
• Alexander Fleming in 1928
• Inhibits the growth of bacteria
Macrophage (WBC) engulfs a bacterium in the immune system:
Bacteria Structure:
 Classified by shape, size, staining, environment, & color Cynobacteria & Salmonella
 
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 For many years, the evolutionary relationships of bacteria were so poorly understood that they were classified only on the basis of their shape and staining characteristics.
 
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 These characters can still be useful in the early stages of identification, but more recent advances in DNA and RNA sequencing give us a more accurate idea of origins and relationships among these tiny, vital organisms. ..
 
. Each of these slides has three separate smears, each with a different shape of bacteria. Rod-shaped bacilli (sing., bacillus) are the most common. Escherichia coli (our mammalian gut symbiont), Lactobacillus spp. (which may be agents of tooth decay or ingredients in yogurt) and Bacillus anthracis (a pathogen causing anthrax in sheep and humans) are examples.
 
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. Spherical cocci (sing., coccus) are also common. Streptococcus spp. are chain-forming cocci responsible for ailments such as strep throat in humans. Staphylococcus spp. form clusters reminiscent of tiny bunches of grapes (staphylo is Greek for "cluster"), and are responsible for those nasty "staph" infections (and often, gangrene) found in untreated puncture wounds.
 
 
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Spiral-shaped spirilla (sing., spirillum) are the largest of these three types, and the simplest to identify. Maybe you should start with those. . .
 
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Asexual Reproduction in Prokaryotes
You are probably most familiar with mitosis as the mode by which cells reproduce themselves. Because prokaryotes have a single, circular chromosome rather than the sets of chromosomes found in the more familiar eukaryotes, mitosis does not occur in prokaryotes. Instead, most replicate via a process of binary fission.
 
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EUBACTERIA
The "true bacteria" are classified on the basis of several characteristics, of which perhaps the most familiar is the Gram Stain method.
 
 
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Gram negative Eubacteria
About 75% of known eubacteria are gram negative. They include the gliding bacteria, the spirochetes, the curved (vibrios) and spiral (spirillae) bacteria, gram-negative rods, gram-negative cocci, rickettsias, chlamydias and the photosynthetic cyanobacteria.
 
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 Gram negative bacteria form an extremely diverse group. The fact that they are all gram-negative does not necessarily imply that they comprise a monophyletic taxon. .
 
 
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Gram positive Eubacteria
Not as diverse as the gram-negative bacteria, the gram-positives still make up an impressively varied group. This division includes the gram-positive rods, gram-positive cocci, and the actinomycetes, which exhibit superficial similarity and function (but no evolutionary relationship) to the (eukaryotic) fungi .
 Spiral or spirilli)
 Spirochete Bacteria
Bacilli Tuberculosis Bacteria:
Tuberculosis: Bacterial infection
IV 3-4Bacteria reproduction:
Sexual
• Conjugation
• Exchange of DNA
• Variety in
• Changing conditions
Asexual
• Binary fission
• Mitosis
• Replicate
• Non-changing conditions
IV 5. Aerobic Bacteria require oxygen & can make cavities!
Anaerobic Bacteria live without oxygen, in our intestines & may be in polluted waters
• E. Coli from human feces
• Helpful in the intestines
• Harmful in other parts of the body
 
?Life on Mars?
 
Bacteria cultures:
• Inoculate = to place
• Agar = culture medium (nutrients)
• One colony (circle)= billions of bacteria
• A colony begins from one bacterium
• Incubate at 37oC= body temperature
• DO NOT OPEN THE PLATES AFTER INCUBATION!
Bactericide test strip:
• Kills germs! Versus
• Bactericide?
• Antibiotic?
• Mouth wash
• Neosporin
• Cleaning agents
Summary Questions:
6. View under higher magnification with stains for specific types of bacteria
7. Classified by shape:
a. round = cocci
b. rods = bacilli
c. spiral = spirilli
Genetic Engineering of Insulin
Restriction Enzymes:Made by some Bacteria
Warts are a skin virus!
Plant peach virus
Polio virus
Herpes mouth virus:
Rabies Virus
Hepatitis B virus (Liver)
Virus structure:
• Protein Coat
• DNA or RNA for replication
• Adsorb-tion site
• Host specific
HIV virus structure:
Cow pox vaccination 1749
• Acquired Immunization
• Artificial injection of a small amount of virus
• Body’s immune response makes antibodies
Chicken Pox Virus
Viral Replication:
Bacteriophage
• Bacteria “eating” virus
• Virus uses the bacteria as a host
• For Viral replication
Lytic Cycle (Replication) of a Virus - “AVIRAL”
Transduction:
HIV Virus
HIV virus infects T-cells
• HIV virus Weakens the immune system
• AIDS patients die of “common” diseases when T cell (WBC) count falls
AIDS = break down of the immune system & death due to common diseases versus death by AIDS virus
 
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MYCOPLASMAS
These are the smallest living cells ever discovered, and are believed to have the minimum amount of DNA needed to code for a functioning cell. They lack the cell wall characteristic of the other three types of bacteria.
 
. Most mycoplasmas exist as intracellular plant or animal parasites, a life history which protects them from environmental osmotic stresses as long as the host cell is functioning properly. Penicillin, an antibiotic lethal to most other bacteria because it interferes will cell wall formation, is not effective against the naked little mycoplasmas. .
 
.The Many Shapes of Bacteria
As you already know, bacteria come in a vast array of shapes and sizes, and there are several taxonomically distinct groups. Take a slide to your station and observe under the compound microscope. Remember: bacteria are extremely small. Focus with extreme care, on low power first, and don't break the slide!
 
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Bacterial Locomotion
Bacteria exhibit various modes of locomotion, including "squirming", gliding and propulsion via flagella. The flagellum of a bacterium is quite different from the flagellum of a eukaryote.
 
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It is composed of a protein called flagellin, not found in eukaryotes, whereas the eukaryotic flagellum is composed of a symmetrically arranged series of microtubules. Unlike the eukaryotic flagellum, which beats with a wavelike motion, the bacterial flagellum rotates to propel the little beastie through its substrate. .
 
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Close up of the
flagellum of
Spirilla volutans .
The Economic Importance of Bacteria
 
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. Other organisms may serve as vectors to spread bacteria. Flies, cockroaches, biting insects, rodents and other animals get a lot of the blame for transmitting diseases to humans. But if the truth be told, you're in a lot more danger of contracting something dangerous from personal contact with your fellow Homo sapiens than you are from being licked by a fly (or your dog!). .
 
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Nitrogen-fixing bacteria (such as these Rhizobiumsp.) inhabit the root cells of plants in the legume family (Fabaceae). These moneran symbionts convert gaseous nitrogen from the atmosphere (N2) into usable "fixed" nitrogen (ammonia, nitrite and nitrate) which can be absorbed by the roots and used by the plant to manufacture protein and nucleic acids.
 
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Other bacteria, such as these Streptomyces spp., are sources of life-saving medicines. This genus yields the powerful antibiotic known as streptomycin. Actinomycetes are the source of actinomycin. .
 
 
• The Enterotube™ II is a self-contained sterile plastic tube with 12 compartments containing distinct media that permit different biochemical tests to be performed. The Enterotube™ II has its own enclosed inoculating wire that allows simultaneous inoculation and completion of 15 standard biochemical tests for the identification of enteric unknowns. After incubation, the specific chambers show color changes for positive tests. The identification of the unknown is determined from the BBL™ Enterotube™ II Interpretation Guide. Each organism is identified with a 5-digit number based on the positive and negative test reactions in the Enterotube™ II.
 
 
 
Sponge Activity-What did you learn today?
• 1. Which choice below can be found in gram-negative bacteria, but not in gram-positive bacteria? (Concept 27.1)
• 2. The prokaryotic organisms most likely to be found living in salt ponds are the _____. (Concept 27.3)
• 3. Which clade of archaea contains the extreme halophiles and methanogens? (Concept 27.3)
• 4. An ecological relationship between organisms of different species that are in direct contact can best be described as _____. (Concept 27.4)
• 5. Genes for the resistance of antibiotics are usually located _____. (Concept 27.1)