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S. aureus most commonly causes skin infections like folliculitis, boils, impetigo, and cellulitis that are limited to a small area of a person's skin. S. aureus can also release toxins (poisons) that may lead to food poisoning, toxic shock syndrome
Staphylococcus aureus
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19–1 Bacteria
Photo Credit: Michael T. Sedam/CORBIS
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19-1 Bacteria
The smallest and most common microorganisms are prokaryotes—unicellular organisms that lack a nucleus.
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4. Classifying Prokaryotes
All prokaryotes were once placed in the Kingdom Monera.
Recently, biologists divided them into two different kingdoms: the Eubacteria and the Archaebacteria.
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5. Classifying Prokaryotes
Eubacteria
Eubacteria have a cell wall that protects the cell and determines its shape.
The cell wall of eubacteria contain peptidoglycan.
Eubacteria have a cell membrane that surrounds the cytoplasm.
Some eubacteria have a second membrane that provides added protection.

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7. Classifying Prokaryotes
E. coli, a Typical Eubacterium
Ribosomes
Cell Wall
Cell Membrane
Peptidoglycan
A bacterium such as E. coli has the basic structure typical of most prokaryotes: cell wall, cell membrane, and cytoplasm. Some prokaryotes have flagella that they use for movement. The pili are involved in cell-to-cell contact. The cell walls of eubacteria contain peptidoglycan.
Flagellum
DNA
Pili
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CAPSULE
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9. Classifying Prokaryotes
Eubacteria include organisms that live in a variety of environments, including:
in fresh and salt water
on land
in the human body
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10. Classifying Prokaryotes
Archaebacteria 
The cells walls of archaebacteria do not contain peptidoglycan. Archaebacteria have different membrane lipids (different bonds and fatty acids). In addition, the DNA sequences of key archaebacterial genes are more like those of eukaryotes than those of eubacteria.
Who are we more closely related to?
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Archae Environments
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12. Classifying Prokaryotes
Many archaebacteria live in extreme environments.
Methanogens live in oxygen-free environments, such as thick mud and animal digestive tracts.
Other archaebacteria live in salty environments or in hot springs where water temperatures approach the boiling point.
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13. Identifying Prokaryotes
Prokaryotes are identified by characteristics such as:
1. shape
2. the chemical nature of their cell walls
3. the way they move
4. the way they obtain energy
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14. Identifying Prokaryotes
1. Shape 
Rod-shaped prokaryotes are called bacilli.
Prokaryotes can be identified by their shapes. Photo Credit: ©David Scharf/Peter Arnold, Inc.
Bacilli
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15. Identifying Prokaryotes
Prokaryotes can be identified by their shapes. Photo Credit: ©David M. Phillips/Visuals Unlimited
Cocci
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16. Identifying Prokaryotes
Spiral and corkscrew-shaped prokaryotes are called spirilla.
Prokaryotes can be identified by their shapes. Photo Credit: ©Scott Camazine/Photo Researchers, Inc.
Spirilla
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17. Other shapes seen: Vibrio: Comma shaped with flagella
Spirochete: wormlike spiral shape

19. Grouping of Bacteria Diplo- Groups of two Strepto- chains
Staphylo- Grapelike clusters

22. Diplococcus

23. Streptococcus Causes Strep Throat

24. Staphylococcus

25. Bacillus - E. coli

26. Streptobacilli

27. Spirillum

28. Spirochetes

29. Identifying Prokaryotes
2. Chemical Nature of Cell Walls
Two different types of cell walls are found in eubacteria. A method called gram staining tells them apart.
Gram-positive bacteria have thick cell walls with large amounts of peptidoglycan. (stained purple)
Gram-negative bacteria have thinner cell walls inside an outer lipid layer. (stained pink)
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32. Identifying Prokaryotes
3. How Bacteria Move
Prokaryotes can be identified by whether they move and how they move.
Flagella
Gliding
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33. Flagella CLASSIFICATION Monotrichous: 1 flagella
Lophotrichous: tuft at one end
Amphitrichous: tuft at both ends
Peritrichous: all around bacteria

35. What is this type of bacteria ?
Question:
What is this type of bacteria ?

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Metabolic Diversity
4. The Way They Obtain Energy:
Prokaryotes are divided into two main groups:
Heterotrophs get their energy by consuming organic molecules made by other organisms.
Autotrophs make their own food from inorganic molecules.
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37. 4) Metabolic Diversity: Obtain Energy
Heterotrophs 
Prokaryotes that take in organic molecules for both energy and a supply of carbon are called chemoheterotrophs.
Prokaryotes that use sunlight for energy, but take in organic compounds as a carbon source are called photoheterotrophs.
chemoheterotrophs
photoheterotrophs
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38. 4) Metabolic Diversity: Obtain Energy
Autotrophs 
Photoautotrophs use light energy to convert carbon dioxide and water to carbon compounds and oxygen.
Chemoautrophs perform chemosynthesis. They make organic carbon molecules from carbon dioxide, but do not require light as energy.
Chemoautrophs use energy from chemical reactions. (oxidize inorganic matter such as iron or sulfur to make food (archae in hydrothermal vents)
Photoautotrophs
chemoautotrophs
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Modes of Nutrition
Saprobes – feed on dead organic matter (heterotrophs)
Parasites – feed on a host cell (heterotrophs)
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41. 4) Metabolic Diversity: Release Energy
Releasing Energy: How bacteria get their energy
Bacteria need a constant supply of energy, which is released by the processes of cellular respiration or fermentation or both.
Respiration: this is the process in which cells release energy (energy is produced) in the presence of oxygen
Fermentation: this is a process in which cells release energy (energy is produced) in the absence of oxygen
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Metabolic Diversity
Obligate aerobes require a constant supply of oxygen. (ex: streptococcus)
Bacteria that live without oxygen because they may be killed by it are called obligate anaerobes. (ex: Clostridium Botulinum)
Bacteria that can survive with or without oxygen are known as facultative anaerobes. (ex: E. coli)
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Facultative Anaerobe
Staphylococcus (gram positive)
Boils, impetigo, food poisoning, cellulitis, and toxic shock syndrome
Escherichia coli (gram negative)
- lower intestine of warm-blooded animals; food poisoning in humans
Listeria (gram positive) - found in food; grows in refrigeration; cantaloupes
Obligate Aerobe
Pseudomonas aeruginosa (gram negative) – can be found on medical equipment; causes disease in animals
Bacillus (gram positive)
Obligate Anaerobe
Clostridium botulinum -
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44. Growth and Reproduction
Most prokaryotes reproduce by binary fission.
Some prokaryotes take part in conjugation.
Other prokaryotes produce spores.
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45. Growth and Reproduction
Binary Fission 
Binary fission is a type of asexual reproduction in which an organism replicates its DNA and divides in half, producing two identical daughter cells.
Most prokaryotes reproduce by binary fission, producing two identical “daughter” cells. Photo Credit: ©Dr. Dennis Kunkel/Phototake
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46. Growth and Reproduction
Conjugation 
During conjugation, a hollow bridge forms between two bacterial cells, and genes move from one cell to the other.
This transfer of genetic information increases genetic diversity in populations of bacteria.
Some prokaryotes take part in conjugation, in which genetic information is transferred from one cell to another by way of a hollow bridge. Photo Credit: ©Dr.Dennis Kunkel/Phototake
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47. Growth and Reproduction
Spore Formation 
In unfavorable growth conditions, many bacteria form spores.
An endospore forms when a bacterium produces a thick internal wall that encloses its DNA and some of its cytoplasm.
Spores can remain dormant for months or years.
Spores allow bacteria to survive harsh conditions.
Some prokaryotes produce endospores, which allow them to withstand harsh conditions. Credit: ©A. B. Dowsett/Science Photo Library/Photo Researchers, Inc.
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48. Growth and Reproduction
First, the bacterium senses that its home or habitat is turning bad: food is becoming scarce or water is disappearing or the temperature is rising to uncomfortable levels. So it makes a copy of its chromosome, the string of DNA that carries all its genes.
Then, the rubbery cell membrane that surrounds the bacterial cell fluid begins pinching inward around this chromosome copy, until there’s a little cell within the larger bacterial cell. This little cell is called the "daughter cell" and the bigger, original one, what starts out as the "vegetative cell" in this illustration, is now called the "mother cell." Next, the membrane of the mother cell surrounds and swallows up the smaller cell, so that now two membrane layers surround the daughter cell. Between these two membranes a thick wall forms made out of stuff called peptidoglycan <pep-tid-oh-gly-can>, the same stuff found in bacteria’s rigid cell walls. Finally, a tough outer coating made up of a bunch of proteins forms around all this, closing off the entire daughter cell, which is now a spore. As the mother cell withers away or gets blasted by all kinds of environmental damage, the spore lies dormant, enduring it all, just waiting for things to get better
Spore Formation
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49. Importance of Bacteria
Bacteria are vital to the living world.
Some are producers that capture energy by photosynthesis.
Others are decomposers that break down the nutrients in dead matter.
Still other bacteria have human uses.
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50. Importance of Bacteria
Decomposers
Bacteria recycle nutrients and maintain equilibrium in the environment.  
Bacteria also help in the treatment of sewage.
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51. Importance of Bacteria
Nitrogen Fixers 
Plants need nitrogen gas to be changed chemically to ammonia or other nitrogen compounds, which certain bacteria produce.
The process of converting nitrogen gas into a form plants can use is known as nitrogen fixation.
Many plants have symbiotic relationships with nitrogen-fixing bacteria.
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52. Importance of Bacteria
Human Uses of Bacteria
We depend on bacteria for many things, including:
foods and beverages
removal of waste and poisons from water
mining minerals from the ground
synthesis of drugs and chemicals via genetic engineering
production of vitamins in human intestines
Future use: Energy source????
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GUT FLORA
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54. Antibacterial resistance
What is it? Notes during video!
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19–1
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19–1
Which characteristic distinguishes eubacteria from archaebacteria?
Eubacteria lack peptidoglycan in their cell walls.
Eubacteria contain peptidoglycan in their cell walls.
Eubacteria lack a nucleus.
Eubacteria do not possess mitochondria.
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19–1
Rod-shaped prokaryotes are called
bacilli.
cocci.
spirilla.
streptococci.
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19–1
Bacteria that must live without oxygen are called
obligate aerobes.
facultative anaerobes.
obligate anaerobes.
facultative aerobes.
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19–1
Prokaryotes that make their own food molecules from carbon dioxide and water but live where there is no light are called
photoautotrophs.
photoheterotrophs.
chemoautotrophs.
chemoheterotrophs.
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19–1
Bacteria that attack and digest the tissue of dead organisms are called
decomposers.
nitrogen fixers.
chemoautotrophs.
archaebacteria.
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61. END OF SECTION