Bacteria

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Bacteria
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Characteristics
Ancient bacteria

• Lack of a membrane bound nucleus
• No membrane bound organelles
• Prokaryotes
• Most are unicelluar
• Types
• Ancient bacteria
• True bacteria

True bacteria
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Size of Bacteria

• One pound of fertile soil may contain as many as
  50 million bacteria
• Measured in microns

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Habitats of Bacteria

• Are found in more varied habitats and
  environments than any other living organism
• Exist on animals and plants
• Exist in soil, ocean, desert, hot springs, snow

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3 basic Bacteria Shapes

• 1. Coccus
• Spherical or oval shape
• Average size is about 0.5 1.0 micrometer (1
  micrometer 1/1,000,000 of a meter)
• 2. Bacillus
• 3. Spirilla
• Spiral shaped

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Bacteria Shapes
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Coccus Bacteria

• Diplococcus- pair of cocci
• Staphylococcus- clusters of cells, irregular
  shapes like grapes (Staphylococcus aureus)
• Streptococcus- chain of cocci (Streptococcus
  pygenes)
• Tetrad- square of 4 cocci
• Sarcina- cube of 8 cocci

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Bacteria Structure

• Capsule-
• Layer of polysaccharides (sometimes proteins)
  that protects the bacteria cell
• Not present in all bacteria cells
• Often associated with pathogenic bacteria because
  it serves as a barrier against phagocytosis by
  white blood cells
• Produces serious infection
• Pneumonia organism

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Structure - continued

• Plasma membrane
• Lipid bilayer
• Numerous proteins moving within layer responsible
  for transporting ions, nutrients and waste
• Cell wall
• Composed of peptidoglycan
• Cell wall maintains the overall shape of a
  bacteria cell

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Structure - continued

• Pilli-
• Hollow, hair-like structures made of protein that
  allow bacteria to attach to other cells
• Slime layer
• Excreted by the cell under certain conditions
  when the environment is unfavorable
• Endospore
• Non-reproductive structure
• Dormant form of a bacteria
• Protects cell from high temperatures, most
  disinfectants, low energy radiation, drying out
  etc.

Endospore
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Bacteria cells lack

• Nucleus
• Nuclear membrane
• Mitochondria
• Bacterial cells use enzymes found on the cell
  membrane instead

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Motility

• Flagella
• Can have one or more flagella arranged in clumps
  or spread all over the cell
• The flagellum is a rigid structure that rotates
  like a propeller
• Sliding
• Has direction like a floor buffer
• Brownian movement
• Involves mostly cocci forms
• Collisions of bacterial particles with other
  molecules in a fluid environment

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How fast are they?
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Ideal Conditions for Bacterial Growth

• Temperature
• 80F to 100F
• Cause of human infections (98.6F body temp.)
• Moisture
• Most active bacterial cells are 90 water
• Prolonged dryness will kill bacteria of most
  species
• Darkness
• Sunlight retard growth
• UV radiation kills cells
• Food Source
• Most pathogenic bacteria require living tissues

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Thursday, May 1

• Do Now have out bacteria outlines
• 1. Continue with Bacteria
• 2. Bacteria CD Rom
• 3. Begin work on rest of packet with viruses
• HW- Objectives due Friday

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Bacterial Nutrition - Heterotrophic bacteria

• Utilizes oxygen in growth
• Obtain energy from organic compounds
• Saprophytes- live off of dead organic matter
• Parasites- live off of animals or plants and
  cause damage or even death
• Have the ability to withstand the hosts defense
  mechanisms

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Bacterial Nutrition - Autotrophic bacteria

• Use carbon dioxide as their source of carbon for
  growth
• Obtain energy from light or inorganic compounds
• Phototrophic bacteria- use photosynthesis to make
  ATP from light energy
• Chemosynthetic bacteria- use organic and
  inorganic chemicals as their energy source

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Bacterial Respiration

• Obligate aerobes- require oxygen for respiration
• Examples
• Diptheria- affects the throat and respiratory
  system in humans
• Tuberculosis- spreads to organs and other systems
  by blood or lymph
• Cholera- infects intestines, associated with
  contaminated water

Cholera
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Bacterial Respiration

• Obligate anaerobes- cannot grow in the presence
  of oxygen
• Examples
• Tetanus- lockjaw affects the neuromuscular
  junction
• Botulism- food born botulism infects intestines
  and passes into the bloodstream

Botulism
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Bacterial Respiration

• Facultative anaerobes-
• Grow best as aerobes, but can grow as anaerobes

Serratia cells found in soil
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Gram Staining

• Gram positive
• Contain a lot of peptidoglycan in the cell wall

• Gram negative
• Less peptidoglycan in the cell wall
• Contain a second membrane external to the cell
  wall that is chemically different than the cell
  membrane

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Gram Staining
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Bacterial Reproduction

• Transverse Binary Fission
• Simpler than cell division
• Can occur in 20 minutes to 20 hours depending on
  species

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Reasons for the Death of Bacteria Cells

• Cells cannot resume cell division once in a new
  environment
• Crowding
• Food competition
• Metabolic wastes
• Colony formation- stability or death

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Bacterial Genetic Recombination

• Transduction-
• Bacteria genes are carried by a donor cell to a
  recipient cell by a bacteriophage

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Bacterial Genetic Recombination

• Conjugation-
• Genetic information is passed among
  microorganisms
• Important adaptation for bacteria to gain
  resistance against antibiotics

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Bacterial Genetic Recombination

• Transformation-
• The taking of DNA from a donor bacterium cell to
  another recipient bacterium cell
• Griffiths experiment

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Spore Formation

• When conditions are unfavorable, bacteria can
  form spores to protect themselves until
  conditions become favorable again
• This process starts in a resting stage where the
  endospores are formed in the mother cell when
  nutrients are limited to ensure survival of the
  bacteria

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Spore Formation

• Endospores are used because they are
• Highly resistant to adverse conditions
• Little to no metabolic activity takes place
• Hard to kill
• Anaerobic
• Can remain in the endospore state for as long as
  30 years and still be effective

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Beneficial Bacteria in the Soil

• Green plants absorb minerals from the soil
• Use these minerals in synthesizing organic
  compounds
• Animals consume plants and rearrange compounds
  for their own needs
• Remains of living organisms are left in complex
  forms that must be broken down
• Decomposers will break down tough materials, like
  cellulose and chitin
• Materials later are returned to the Earth and
  atmosphere

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Bacteria in Industrial Processes

• Making of vinegar-
• Yeasts ferment sugar into fruit juice that is
  changed into alcohol
• Bacteria oxidize the alcohol and change it to
  acetic acid

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Bacteria in Industrial Processes

• Making of sauerkraut
• Cabbage leaves are shredded and placed in an
  airtight jar
• Anaerobic bacteria (lactobacillus) ferment the
  sugar in cabbage leaves and converts it to lactic
  acid

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Bacteria in Industrial Processes

• Tanning of leather
• In ancient times, animal skin was shaved and
  cleaned and pigeon or hen dung was infused
  followed by an infusion of dog dung. This set
  off a fermentation reaction and softened the
  leather

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Bacteria in Industrial Processes

• Retting of Flax
• Flax- woody stem of the flax plant is used to
  make linen
• Takes 4 to 6 days in warm water tanks and up to 3
  weeks in cold water or dew. Water helps soil
  bacteria penetrate the woody stems. The break
  down the pectins that hold together the woody and
  fibruous portions of the plant. Then is dried in
  open fields

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Bacteria in Industrial Processes

• Silage-
• Contains organic acids that are the products of
  sugar and starch fermentation. Anaerobic
  condition that prevents plant decay and permits
  bacteria (lactobacillus) to ferment sugar in the
  plants

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Bacteria in Industrial Processes

• Tobacco-
• Curing process
• Brings out the flavor and smell of tobacco.
  Bacteria ferment carbohydrates in the moist
  leaves producing special flavors

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Bacteria in the Dairy Industry

• Milk
• Ideal culture medium for bacteria. Most
  countries require the destruction of unwanted
  microorganisms and pathogenic bacteria
• Pasteurization
• Destruction of disease-causing bacteria in milk,
  fruit juices, wine and other malt beverages by
  heat
• Destroys milk-souring bacteria
• Temperature needs to be high enough to kill
  harmful bacteria. Flash heat method (161F for 15
  minutes) is more effective than holding methods
  (145F for 30 minutes)

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Bacteria in the Dairy Industry

• Butter
• Raw cream is separated from whole milk and is
  pasteurized. Various bacteria are used to ripen
  and adjust the pH of the cream to achieve the
  desired flavor. The liquid is poured off and
  buttermilk is made from this liquid.
• Cheese
• Use whole or skim cow or goat milk. Bacteria is
  added to form lactic acid to cause curdling.
  Cottage cheese curd is eaten while moist and
  unripened. Cream cheese butter fat is added to
  the curd. Other cheeses processed salted and
  pressed to remove moisture then ripened.

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Food Spoilage and Preservation

• Preservation of food destroys all bacteria
  present and seals the food in the appropriate
  container (canning can be preserved indefinitely
  if done correctly)
• Environmental control maintain foods under
  appropriate conditions to inhibit bacterial
  growth and activity. Salt curring plasmolysis
  of cells (meat- prevents botulism)
  Refrigeration retards growth and reproduction of
  bacteria Quick freezing temps of 0 to -10 to
  -15 degrees F ceases all bacterial activity
  Dehydration removes water from food so bacteria
  cannot grow Chemicals/ Radiation food can be
  kept indefinitely

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Bacterias Relatives

• Rickettsiae between bacteria and viruses
• Bacteria- cellular and reproduce by fission
• Virus- grow and reproduce only in living cells
• Transmitted by insects (ticks, mites, human body
  louse)
• Live in the carrier hosts intestines but do not
  cause the disease
• Diseases caused Rocky Mountain Spotted Fever,
  Trench Fever, and mysterious Q fever

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Bacterias Relatives

• Spirochetes between bacteria and protozoans
• Live in the human body and cause disease
• Pathogenic
• Live in the bloodstream and invade the nervous
  system
• Spread in material that is discharged from
  lesions or eruptions of the skin and mucous
  membranes during the early stages of the disease

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Edward Jenner

• First experimental vaccination for cow-pox virus
  to build immunity against smallpox. Coined the
  term vaccination from the Latin vacca meaning cow

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Louis Pasteur

• germ theory of disease
• Weakened forms of microbe to be used as
  immunization
• Rabies was caused by something so small and it
  was later used to treat humans
• Developed pasteurization to destroy the bacteria
  in food without harming the food
• Studied why alcohol contaminated during
  fermentation

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Alexander Fleming

• Discovered lysozyme (a protein found in healthy
  noses and tears)
• Used a culture of his own nasal mucus to
  inhibited the growth of Staphylococcus cultured
  from the same mucus
• Found a strain of bacteria that was particularly
  sensitive to lysozymes

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Bodys defenses against bacteria

• Neutralizing antibodies block viruses from
  attaching and entering the host
• Virus specific antibodies can act against
  proteins on the virus surface
• Overuse of antibodies can lead to the development
  of resistant bacteria