BACTERIA

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Ch. 18Prokaryotes
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All organisms in domains Archaea and Bacteria are
considered prokaryotic.

• What does it mean to be prokaryotic?
• Do NOT have a nucleus.
• Do NOT have membrane bound organelles (like
  mitochondria, ER, Golgi)
• But they DO have ribosomes, DNA, cell membrane,
  cytoplasm/cytoskeleton

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18.4 Bacteria and Archaea

• Prokaryotes are widespread on Earth
• Prokaryotes are the most widespread and abundant
  organisms on Earth.
• for perspective
• humans (eukaryotes) are one species with 7
  billion individuals
• a gram of soil may contain 10,000 types of
  bacteria (prokaryotes) and 5 billion bacterial
  cells

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Prokaryotes are widespread on Earth.

• prokaryotes are
• microscopic
• one of the earliest life forms
• found inside your body, inside volcanoes, on your
  pencil- EVERYWHERE (ubiquitous)!
• prokaryotes can be grouped based on their need
  for oxygen
• aerobic- need oxygen
• anaerobic- do not need oxygen

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The domain Bacteria and Archaea are structurally
similar but have different molecular
characteristics.

• There are two domains that contain prokaryotes
  Bacteria and Archaea
• domain Bacteria is more diverse and widespread
  than domain Archaea
• domain Archaea is more likely to be found in
  extreme environments than domain Bacteria

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• Domain Archaea
• Kingdom Archaea (Archaebacteria)

• Domain Bacteria
• Kingdom Bacteria (Eubacteria)

• ancient
• most heterotrophs (some autotrophs)
• cells walls WITHOUT peptidoglycan unique lipids
• found in harsh/extreme environments
• Examples
• methanogens- dont need oxygen (anaerobic), make
  methane gas
• thermophiles- very hot water
• halophiles- very salty conditions, 10x saltier
  than ocean water

• most diverse
• most are heterotrophs (some autotrophs)
• cell walls WITH peptidoglycan
• found everywhere
• Examples
• Escherichia coli
• Clostridium botulinum
• Bacillus anthracis

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Archaea in San Francisco Bay area extremely
high salinity. What kind of archaeans are
these?
halophiles
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Structural Comparisons of Bacteria and Archaea

• both are small, single-celled organisms
• both have
• cell walls
• plasma/cell membranes
• DNA (chromosome) is in a circle in the cytoplasm
  (not found in a nucleus because they dont have a
  nucleus)
• ribosomes

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Structural Comparisons of Bacteria and Archaea

• both may have plasmids
• plasmid small piece of genetic material (DNA)
  that can replicate separately from the
  prokaryotes main chromosome

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Structural Comparisons of Bacteria and Archaea

• both are generally motile able to move on their
  own
• flagellum whiplike structure outside of a cell
  used for movement
• attached to plasma membrane and cell wall

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Structural Comparisons of Bacteria and Archaea

• both often contain pili
• pili thin, short, numerous projections that
  help prokaryotes stick (attach) to surfaces and
  each other pili also function in sexual
  reproduction in bacteria

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• BACTERIA DO NOT HAVE CILIA!!!!

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Structural Comparisons of Bacteria and Archaea

• both have multiple shapes
• Archaea come in many shapes
• Bacteria have 3 basic shapes
• bacilli(us) rod-shaped
• spirilla(um) or spirochete spiral-shaped
• cocci(us) spherical (round)

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Bacterial Shapes
bacillus
coccus
spirillum
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Structural Comparisons of Bacteria and Archaea

• Label

coccus
bacillus
spirillum
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Structural Comparisons of Bacteria and Archaea

• Bacteria have 2 basic arrangements
• strepto strips or chains
• staphylo- clusters

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Structural Comparisons of Bacteria and Archaea

• ?If your doctor said you had Strep throat
  (Streptococcus), what would shape and
  arrangement of the bacteria look like under the
  microscope?

• ?If your doctor said you had a staph infection
  (Staphylococcus), what would shape and
  arrangement of the bacteria look like under the
  microscope?

• Answer
• clusters of circles
• Draw

• Answer
• chains of circles
• Draw

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Bacteria Structure and Function
Fill in the missing structural terms in your
notes in the Structure and Function Chart.
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Bacteria Structure and Function
Fill in the terms from the chart on the diagram
below. Then, number these structures (1,2,3)
starting with the outside of the cell and moving
to the inside cell wall, capsule, plasma
membrane
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Bacteria have various strategies for survival.

• Reproductive strategies
• binary fission
• conjugation
• and
• Strategies for surviving harsh conditions

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Gene Exchange in Prokaryotes

• binary fission prokaryotic asexual reproduction
• Bacteria divides in half producing identical
  offspring.
• chromosome copies itself (like in DNA
  replication)
• the cell grows to double its size
• plasma membrane grows inward and divides the cell
  into two, each with a full set of the original
  cells genes.

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• binary fission prokaryotic asexual reproduction

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Gene Exchange in Prokaryotes

• conjugation exchange of genetic material
  through a hollow bridge of pili connecting 2 or
  more cells

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Surviving Harsh Conditions

• endospore specialized cell with a thick,
  protective wall formed for survival during
  unfavorable conditions
• bacterium copies its chromosome
• produces a wall around the copy
• thick wall withstands drying out (desiccation),
  temperature change, and disinfectants
• can last for centuries

Examples Bacillus anthracis (causes anthrax)
Clostridium botulinum (causes botulisma form of
food poisoning)
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18.5 Beneficial Roles of Prokaryotes

• Prokaryotes provide nutrients to humans and other
  animals.
• prokaryotes are key in animal digestive systems
  in balanced communities
• mutualistic symbionts
• host benefits
• make vitamins and other compounds
• keep away harmful microbes by filling niches they
  might occupy (out-competing them)
• bacteria benefits
• break down food while getting a place to live
• place to live has stable pH and temperature

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Develop mutualistic relationships with other
organisms Ex. the fish provides the
bioluminescent bacteria under its eye with
organic materials, the fish uses its living
flashlight to lure prey and to signal mates.
potential mates.
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• Prokaryotes provide nutrients to humans and other
  animals.
• many foods humans eat are fermented by bacteria
• ferment chemically break down
• yogurt
• pickles
• cheese
• sauerkraut
• soy sauce
• vinegar

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• Prokaryotes play important roles in ecosystems.
• PRINCIPLE DECOMPOSERS (along with fungi)
• recyclers of carbon, nitrogen, hydrogen, and
  sulfur through ecosystems
• photosynthesizers cyanobacteria produce oxygen
  were key to increasing the oxygen content of
  early earth

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Cyanobacteria
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• Prokaryotes play important roles in ecosystems.
• - nitrogen fixers - fix nitrogen convert
  atmospheric nitrogen into ammonia and other
  nitrogen compounds plants can use
• some nitrogen-fixing bacteria are free-living
• some are symbionts
• legumes plants (peas, beans, alfalfa, and
  clover) with mutualistic relationship with
  nitrogen-fixing bacteria living in nodules in the
  roots
• bacteria provide usable nitrogen to the plant in
  the form of ammonia
• plant provides food and shelter to the bacteria

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• Prokaryotes play important roles in ecosystems.
• bioremediaters break down pollutants
• some bacteria can digest oil, others can digest
  poison
• important role in recycling and composting
• biodegradable able to be broken down by
  bacteria
• many plastics are NOT biodegradable.

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Summary of Beneficial Bacteria (not in notes)

• bacteria are decomposers and nitrogen fixers
• bacteria are used to make certain foods like
  cheese and yogurt.
• bacteria are used in the manufacture plastics
  and many pharmaceuticals.
• bacteria digest cellulose in animals
• bacteria are used in sewage treatment plants
• bacteria are used to make medications and
  biological molecules like insulin (a protein
  bacteria transcribe and translate the human
  gene!)

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18.6 Bacterial Diseases and Antibiotics

• Some bacteria cause disease.
• some bacteria cause disease in plants and animals
  by disrupting the host organisms homeostasis in
  2 basic ways
• invading tissues and attacking cells
• making poisons, or toxins, that can be carried by
  blood through the body

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• Some bacteria cause disease.
• tuberculosis (TB) bacteria invade host tissues
  and use them for nutrients
• Mycobacterium tuberculosis multiply in the lungs,
  killing white blood cells that respond to the
  invasion
• hosts reaction is to release enzymes that cause
  swelling results in lung damage
• a healthy immune system can usually defeat a
  potential TB infection

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• Some bacteria cause disease.
• food poisoning
• Staphylococcus aureus normally live in nasal
  passages
• when transferred to food it results in serious
  illness
• toxin it produces is not destroyed by cooking
• Clostridium botulinum causes botulism which can
  be deadly due to the toxin produced by the
  bacteria
• usually caused by improper canning of foods
  contaminated with spores
• bulging or dented cans may signal the presence of
  the bacteria

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• Some bacteria cause disease.
• opportunistic infections normally harmless
  bacteria can be destructive when introduced to a
  part of the host that is not adapted to them
• example Streptococcus normally present in our
  mouth and noses and the surface of our skin, but
  can become pathogenic in a sore or cut
• also causes strep throat

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• Antibiotics are used to fight bacterial disease.
• antibiotic chemical that kills or slows the
  growth of bacteria, often by stopping bacteria
  from making cell walls
• produced naturally by some species of bacteria
  and fungi
• used as medicine for humans and other animals
  because we/they lack cell walls
• antibiotics dont work on viruses they dont
  have cell walls either
• antibiotics dont work on Archaea either - they
  have a different type of cell wall (no
  peptidoglycan)
• overuse of antibiotics can lead to illness if the
  intestinal flora or microbes are wiped out and
  can lead to resistance

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• Not all antibiotics attack the cell walls of the
  bacterium (penicillin does)
• Some disrupt other processes structures unique
  to bacterial cells
• Ex) tetracyclin disrupts protein synthesis in
  bacteria because of some minor (but important!)
  differences in the process/structures involved

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• Antibiotics are used to fight bacterial disease.
• Gram stain the Gram stain is a method of using
  stain to tell two groups of bacteria within
  Kingdom Bacteria apart. This was an important
  technique developed which is helpful in not only
  diagnosing bacterial infectious but also in
  determining the antibiotic medicine that the
  doctor chooses to treat the infection.
• Gram negative bacteria stain red. These bacteria
  only have a thin layer of peptidoglycan in the
  cell wall, but have an extra layer of lipids.
• Gram positive bacteria stain purple. These
  bacteria have a thicker layer of peptidoglycan in
  the cell wall. Typically Gram bacteria are
  easier to kill with antibiotics.

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• Antibiotics are used to fight bacterial disease.

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• Bacteria can evolve resistance.
• multi-drug resistant bacteria serious public
  health issue resulting from inappropriate and
  incomplete use of antibiotics
• called superbugs
• resistance is a result of natural selection
  bacteria that are unaffected by an antibiotic due
  to a random mutation survive to produce other
  bacteria that are also naturally resistant to the
  same antibiotic (binary fission)
• genes for resistance are acquired when plasmids
  are exchanged during conjugation

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• Bacteria can evolve resistance.
• factors contributing to this issue include
• overuse prescribing an antibiotic for a viral
  infection is just one example
• underuse failing to take the entire course of
  antibiotics prescribed
• the weakest bacteria are destroyed first, leaving
  behind those that are more resistant
• additional (the entire prescription) may kill all
  of the bacteria or reduce their numbers to a load
  your immune system can handle
• misuse feeding them to livestock to increase
  their growth rate leads to resistant bacteria
  present in the food as well as in the animals

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Antibiotic Resistant Bacteria Video Clip
Antibiotic Resistance Video Clip
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Other diseases caused by Bacteria(not in notes)

• anthrax
• lyme disease
• E. coli (food poisoning)
• bubonic plague
• typhoid fever cholera
• strep throat dental caries (cavities)
• diphtheria pneumonia
• Salmonella (food poisoning)

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Yellow bacillus bacteria in the lining of the
human nose. This species causes pneumonia if the
person doesnt have a strong immune system
(opportunistic infection).
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Questions to Ponder

• Why are bacteria important organisms in the
  ecosystem?

• What are the shapes and arrangements of bacteria
  and how can these be used in classification?

• In what ways are bacterial beneficial to us?
  Explain.

• Describe bacterial diseases including cause,
  symptoms, and transmission.