PROKARYOTES 20.2

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PROKARYOTES 20.2
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Introduction to Prokaryotes

• First discovered by Anton van Leeuwenhoek in 1683
  (invention of light microscope)
• Are prokaryotes
• No nucleus
• Exist everywhere
• Grow in colonies so great you can see them with
  the unaided eye

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Classification

• Kingdom Monera???
• Domain Bacteria-Kingdom Eubacteria
• Domain Archaea-Kingdom Archaebacteria

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Characteristics of ALL Bacteria

• Single Celled
• Microscopic (1-10 micrometers)
• Prokaryotic
• Cell Wall
• Ribosomes
• Nucleoid Region (chromosome)

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Archaea Extremophiles?

• Look like bacteria under microscope but LACK
  PEPTIDOGLYCAN in their cell walls, have different
  lipids in their membranes, and DNA sequences of
  key genes are more similar to eukaryotes than
  bacteria
• Referred to as ancient bacteria
• Halophiles Salt Lovers thrive in very salty
  places
• Great Salt Lake, Dead Sea
• Methanogens live in anaerobic environments,
  give off methane, a major greenhouse gas
• intestines and mud at bottom of lakes
• Thermoacidophiles Heat Lovers thrive in very
  hot, acidic environments
• Hot acidic pools Yellowstone National Park
• Some are found in moderate environments

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Eubacteria True Bacteria
Pilus used for attachment Flagellum whip-like
structure used for movement Capsule outermost
structure in some bacteria, protect Cell Wall
protects cell from injury and determines
shape Cell Membrane controls what enters and
leaves Chromosome genetic info Plasmid extra
circular ring of genetic material found in some
bacteria
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Classified by SHAPE
Shape Name Example Diagram
Rod Bacillus (s) Bacilli - (p) Bacillus anthracis (cause of anthrax)
Sphere Coccus (s) Cocci -(p) Streptococcus (cause of scarlet fever and strept throat)
Spiral Spirillum (s) Spirilla (p) Vibrio comma (cause of cholera)
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Shape Continued

• Prefixes used
• Micro single
• Diplo pairs
• Strepto in chains
• Staphylo in clusters
• Examples
• Streptococcus
• Chains of spheres

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Cell Wall (is also used to classify)

• Because of differences in cell wall composition
• Absorb stain differently
• Allow for identification of bacteria
• Gram Stain
• Uses 2 dyes
• Crystal violet (purple)
• Safranine (red)
• Gram one thick layer of carbohydrate
  protein (peptidoglycan) retains purple dye
• Gram - more complex (have 2nd outer layer of
  lipid carbs) retain red

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Bacterial Movement (is also used to classify)

• One or more flagella
• OR
• Lash, snake, or spiral forward
• OR
• Glide along a slime layer they secrete
• OR
• Nonmotile

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How Bacteria Obtain Energy

• Autotrophs make own energy
• Phototroph use suns energy
• Chemotroph obtain energy from inorganic
  molecules (H2S, S, Fe found in harsh
  environments)
• Heterotrophs break down organic compounds for
  energy (aka chemotrophic heterotrophs)
• Refers to most bacteria
• i.e. Salmonella
• Phototrophic Heterotrophs use sun for energy in
  addition to processing organic compounds

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Bacterial Respiration
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Bacterial Growth Reproduction

• Binary Fission asexual, grow replicate DNA,
  split in half- identical
• FAST!!!
• Some can reproduce in under 20 minutes
• If no limiting factors in just 48 hours they
  would mass 4000x the mass of the Earth
• Endospore thick internal wall protecting DNA in
  harsh conditions remains dormant until favorable
  conditions arise
• If reproduce asexually how do they evolve?
• Mutations
• Conjugation sexual, small portions of genes
  (usually in the form of a plasmid) passed over a
  protein bridge new combo of genes introduced

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• Binary Fission

• Conjugation

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Importance of Bacteria

• Production of food
• Cheese, yogurt, buttermilk, sour cream, pickles,
  sauerkraut, vinegar (to name a few)
• Industry
• Digest petroleum help clean up oil spills
• Remove waste products poison from water
• Mine materials from the ground
• Synthesize drugs and chemicals through techniques
  of genetic engineering
• Symbiosis
• At least one organism benefits
• Ex.. E. coli in our intestines helps us digest
  food, it gets nutrients and a place to live

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Bacteria in the Environment

• Nutrient Flow
• Soil is teeming with bacteria
• Recycle decompose dead material (DECOMPOSERS)
• Saprophytes use molecules from once living
  organisms as their source of energy
• Sewage Decomposition
• Break down complex compounds in the sewage into
  simpler compounds
• Produces purified water
• Nitrogen Fixation
• Converts unusable atmospheric nitrogen into
  usable form
• Producers
• Cyanobacteria are major producers in the ecosystem

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20.3 Diseases Caused by Bacteria and Viruses

• Pathogen disease causing agents (can be
  prokaryotes or viruses)
• Diseases caused by bacteria
• Only a few actually cause disease
• Louis Pastuer was the first person to show that
  bacteria cause disease, developed germ theory of
  disease
• Examples diphtheria, tuberculosis, typhoid
  fever, tetanus, Hansen disease, syphilis,
  cholera, bubonic plague
• 2 ways to cause disease
• Damaging host tissue
• Release toxins (poisons) into the host

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Bacterial Diseases
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Controlling Bacteria

• Antibiotics compounds that attack and kill
  bacteria
• Sterilization use chemicals (disinfectants) or
  heat to kill bacteria
• Food Processing/Preservation refrigeration,
  canning, salt, water, vinegar to prolong life of
  foods and protect it from bacteria
• Physical Removal wash to dislodge
• Antiseptics and Disinfectants

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Diseases Caused By Viruses

• Examples (viruses) smallpox, polio, measles,
  AIDS, mumps, influenza, yellow fever, rabies, the
  common cold
• Prevention is the BEST DEFENSE
• Vaccine substance that contains a weakened form
  of the disease-causing virus, stimulates a
  heightened immune response from the host
• Interferon proteins that interfere with the
  infection of body cells by viruses
• Genetically engineered interferon can be produced
  by bacteria
• Antiviral Drugs AZT, acyclovir
• Hygiene

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Viral Diseases
Disease Effect Transmission
Common Cold Sneezing, sore throat, fever, headache, muscle aches Contact with contaminated objects, droplets inhalation
Influenza Body aches, fever, sore throat, headache, dry cough, fatigue, nasal congestion Flu viruses spread in respiratory droplets cause by coughing and sneezing
AIDS Helper T cells are destroyed Contact with contaminated bodily fluids
Chicken pox SKIN RASH OF BLISTERLIKE LESIONS VIRUS PARTICELS ARE SPREAD IN RESPIRATORY DROPLETS CAUSED BY COUGING OR SNEEZING HIGHLY CONTAGEOUS
Hepatitis B Jaundice, fatigue, abdominal pain, nausea, vomiting, joint pain Contact with contaminated bodily fluids
West Nile Fever, headache, body ache Bite from an infected mosquito
Human Papilloma virus (HPV) Genital and anal warts, some cancers (anal, cervical, penile) Sexual contact
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Emerging Viruses

• Viruses that make an apparent sudden appearance
  possible due to environmental disturbances or
  spreads from host species
• We have little or no resistance to them and lack
  methods to control them
• Ex SARS

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Superbugs

• Bacteria that are resistant to whole groups of
  antibiotics and that transfer drug resistance
  genes from one bacterium to another through
  conjugation
• MRSA- Methicillin resistant Staphylococcus aureus

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Prions

• Prions pathogens that are proteins, are
  transmissible from host to host of a single
  species and, sometimes, even from one species to
  another (such as a laboratory animal)
• Destroy brain tissue giving it a spongy appearance

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Prion Diseases

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• Kuru - was once found among the Fore tribe in
  Papua New Guinea whose rituals included eating
  the brain tissue of their recently deceased
  members of the tribe. Since this practice was
  halted, the disease has disappeared. Before
  then, the disease was studied by transmitting it
  to chimpanzees using injections of autopsied
  brain tissue from human victims.
• Scrapie - This disease of sheep (and goats) seems
  to be transmitted from animal to animal in feed
  contaminated with nerve tissue. It can also be
  transmitted by injection of brain tissue.
• Bovine Spongiform Encephalopathy (BSE) or "Mad
  Cow Disease" In 1986, without warning, cows
  began acting strangely, losing control of their
  movements, staggering and stumbling, and
  eventually dying. Farmers watched helplessly as
  the disease they called mad cow spread through
  their cattle.
• The disease affected more than 30,000 cattle in
  1991. Studies of the brains of cattle killed by
  mad cow disease showed that large areas of the
  animals brains had been destroyed. Under the
  microscope, the holes in the tissue make the
  brain resemble a sponge (BSE).
• Its origin appears to have been cattle feed that
  
• contained brain tissue from sheep infected with
  scrapie
• had been treated in a new way that no longer
  destroyed the infectiousness of the scrapie
  prions.
• The use of such food was banned in 1988 and after
  peaking in 1992, the epidemic declined quickly.
• Creutzfeldt-Jakob Disease (vCJD) is the "mad cow"
  disease that people contract when they are
  exposed to food contaminated with bovine
  spongiform encephalopathy (BSE).

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Mad Cow Disease

• Mad Cow Disease