Kingdom Monera - Bacteria

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Kingdom Monera Bacteria Characteristics and
Diversity
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• Bacteria were first identified in 1677 by Antonie
  van Leeuwenhook after he developed a primitive
  version of the compound microscope.
• He originally called all single celled organisms
  he had discovered animalcules and they were
  later separated into groups, one of which
  included bacteria.

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Bacteria are found in three distinct shapes

• Rod shaped
• termed Bacilli

Some bacilli have adapted to survival during
unfavorable conditions by forming dormant or
resting cells called endospores which are
resistant to severe physical and chemical
stresses.
Endospores are a core of DNA that is surrounded
by an impenetrable layer. They can last for
millions of years and are capable of causing some
serious diseases ex. Anthrax (Bacillus
anthraxis) Tetanus (Clostridium tetani)
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• 2. Spherical shaped
• Can be found as single cocci, chains, or
  clumps termed Coccus
• Diploids pairs of spherical shaped bacteria
• ex. Neisseria (can cause gonorrhea, bacterial
  meningitis septicemia)
• Chains of spherical shaped bacteria (Strepto)
• ex. Streptococcus ( cause a variety of human
  disease including meningitis, flesh eating
  disease, and bacterial pneumonia)
• Clusters of spherical shaped bacteria (Staphlo)
• ex. Staphylococcus aureous (can cause a variety
  of human infections including skin infections,
  Toxic Shock Syndrome, meningitis.)

Staphylococcus aureous
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• 3. Spiral shaped
• Actually are a form of rod shaped bacteria
• Termed Spirilla

Leptospirillum

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Bacterial Structure

• Example bacillus structure

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Bacterial Cell Structure

• Internal
• Surrounded by a cell membrane
• Single ring of genetic material (chromosome)
  encased in a nucleoid
• External
• Cell Wall
• Composed of peptidoglycan (as opposed to
  cellulose in plant cells)
• Two types
• Gram positive have a thick cell wall
• Gram negative have a thin cell wall and most
  bacteria fall into this category
• Important in antibiotic use as antibiotics affect
  the ability to produce a cell wall
• Flagella
• Used for motility and are driven by energy
• Can be found alone, at each end, in clusters at
  the poles or all over the cell
• Pili (sing. Pilus) Primitive Sexual reporduction
• Used for transferring genetic material between
  cells

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Methods of Movement
E.coli

1. Flagella rotates and driven by energy at the
   base
2. Bacterial gliding mechanism that includes
   ejection of slime and movement of the pili
3. Twitching motility special pili are used as a
   hook that is extended repeatedly and used to pull
   the bacterium along
4. Changes of buoyancy produce internal gas
   vesicles (pockets) that they use to regulate
   buoyancy in the water to find food and light

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Bacteria have recently been classified by the
environment that they live in

• Archaebacteria live in an environment
• without
  oxygen
• 2. Eubacteria live in an environment with
• oxygen
• Bacteria can also be grouped according to their
  type of respiration
• Obligate aerobes must have oxygen to survive
• Obligate anaerobes can only grow in the absence
  of oxygen
• Facultative anaerobes prefer environments with
  oxygen but can live in environments without oxygen

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Nutrition How do bacteria get the food and
energy they need to survive?

• Some are autotrophs (make their own food)
• Photosynthetic - use of light for energy
• Chemosynthetic use of chemical substances for
  energy
• Some are heterotrophs (obtain food from other
  sources)
• Saprophytic (obtain raw materials from dead and
  decomposing matter)
• Parasitic
• Symbiotic / mutualistic (ex. Bacteria in the
  human colon)
• Chemoheterotrophs must take in organic
  compounds for energy and carbon
• Photoheterotrophs make their own energy via
  photosynthesis but must take in organic
  compounds for carbon

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A few bacteria that cause human disease
Salmonella bacteria (red) causes Salmonella
poisoning
E.Coli bacteria
Helicobacter pylori can cause ulcers, stomach
cancer
Tetanus bacteria
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Modes of Bacterial disease transmission

• Direct contact
• Airborne droplets
• Bacterial toxins in food (ingestion)
• Fecal contamination of food
• Water
• Vector bites (ex. Mosquito)

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Kingdom Monera - BacteriaReproduction and
Ecological Roles
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Bacterial Reproduction

• Bacteria reproduce by a process known as BINARY
  FISSION, a form of asexual reproduction
• Splitting into two
• Sexual reproduction via a process called
  CONJUGATION is not common but does occur. Genetic
  material is exchanged between cells.

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Binary Fission
3. The cell membrane grows inward and separates
the cells. The cells are genetically identical
to one another.
1. A single bacterial cell begins to make copies
of its genetic material
2. The cell membrane begins to elongate and pulls
the genetic material in two different directions
Most bacterial cells will grow to a fixed size
and will then reproduce by binary fission
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Binary Fission Animation
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Bacterial cells undergoing different stages of
binary fission
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ConjugationA primitive form of sexual
reproduction where there is exchange of
chromosome material (genetic material) between
two bacterial cells through a structure called a
pili.
Examples of bacteria that are known to undergo
conjugation include E. coli, Salmonella
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Ecological Roles of Bacteria

• Certain mutualistic bacteria carry out nitrogen
  fixation in the soil next the roots of some
  plants. This allows plants to obtain an easily
  absorbable form of nitrogen needed for growth.
• Bacteria can be used to degrade some organic
  compounds therefore can be used to aid in
  cleaning up oil spills
• Can be used in the place of harmful pesticides
  and leave little to no effect on the environment

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Beneficial Roles of Bacteria

• Bacteria are found as symbionts in
• humans and other organisms. There are
• over 1000 types of bacteria in the average
• human stomach and intestines that
• contribute to immunity, vitamin absorption
• and synthesis, nutrient conversion and
• fermentation. (probiotic supplements contain
• many of these bacteria..)
• Used in preparation of fermented foods ex.
  Yogurt, cheese, soy sauce
• Used in the study of genetics, molecular biology
  and biochemistry because of their ability to
  reproduce so quickly
• Used for making medicines (Insulin)

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Antibacterial Agents and Resistance
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Antibiotics

• Definition a substance produced by a
  microorganism that restricts the growth of
  another microorganism

Penicillium fungi produces the antibiotic
penicillin

• Where do antibiotics come from?
• many are produced from other living organisms
  
  example. Penicillin is collected from the fungi
  penicillium (above) Streptomycin
  comes from the bacteria streptomyces
• some antibiotics are modified chemically and
  some are produced
  synthetically

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How do antibiotics work?

• Antibiotics that target a wide range of bacteria
  are termed broad spectrum. Those that target a
  narrow range are termed narrow spectrum.
• Some antibiotics actually destroy bacteria
  (inhibit cell processes) whereas others keep the
  bacterial cell from reproducing (inhibit binary
  fission)

Above Wafers containing antibiotics are placed
on an agar plate of bacteria. The cloudy areas
show bacterial growth. Circles of poor bacterial
growth show that bacteria will not grow in the
presence of that antibiotic.
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Antibiotic Resistance

• Failure to take entire prescribed dosages of
  antibiotics can lead to the growth of antibiotic
  resistant bacteria.

Improper usage and dosaging of antibiotics also
contributes to the appearance of resistant
bacteria.
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• Staphylococcus aureus bacteria are one of the
  types of bacteria normally found existing on
  human skin surface. They are capable of causing
  skin infections in those with weakened immune
  systems. (see pictures to left)

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Antiseptics

• Definition Antimicrobial substances that are
  applied to living tissue (skin) to inhibit the
  growth of bacteria
• Some destroy bacteria (germicides) and some
  inhibit the growth of bacteria

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Common Types of Antiseptics

• Alcohol (surgical alcohol)
• Used to disinfect skin before injections are
  given
• Boric Acid
• Used in yeast infection treatments, cold sore
  medications,
  burn cream and eye contact
  solution (although not very
  effective)
• Chlorhexidine Gluconate
• Used in gingivitis treatment
• Hydrogen peroxide
• Used for cleaning of wounds (although
  antibacterial soap and water is actually more
  effective)
• Iodine
• Used in pre and post operative cleaning and has a
  very wide scope of antimicrobial activity
• Phenol compounds
• Used in pre operative hand washing, mouth washes
  and throat lozenges
• Natural antiseptics
• Includes saliva, tears, breast milk and gastric
  acids

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Disinfectants

• Definition antimicrobial agents applied to
  non-living objects that destroy microorganisms
  (including bacteria)
• Many disinfectants are harmful (toxic) to humans,
  animals and the environment
• Overuse can lead to resistant strains of bacteria

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Common Types of Disinfectants

• Alcohol
• Wide spectrum, highly effective and non-corrosive
  but are a fire hazard
• Oxidizing Agents (ex. Chlorine, peroxide,
  iodine)
• Destroys the cell membrane of bacteria
• Commonly used in
• Bleach, swimming pool cleaners, drinking water
  treatment)
• UV light
• Can be used in dental tool disinfection or for
  cleaning any other non-porous surfaces