Bacteria

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Bacteria Viruses

• Chapter 19

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Bacteria Size

• Smaller than plant animal cells
• Larger than viruses
• Measured in microns
• (1 x 10-6 meter)

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Two types depend on environment

• Archaebacteria
• Extreme conditions
• Deep sea hydrothermal vents
• Salt Lakes
• Hot springs
• Under Antarctica

• Eubacteria
• Found everywhere
• Human intestine, E. coli
• Dirt
• Water

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Write these downShapes Patterns

• Cocci spherical (Gr. berry)
• Bacilli rod-shaped (L. little sticks)
• Spirilla (spirillum) spiral shaped

• Diplo pairs
• Staphylo clusters
• Strepto - chains

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Now, name these bacteria

• C)

• D)

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Name these bacteria

• B)

• A)

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Cell Structure - Prokaryote

• No organized nucleus
• Has some organelles (i.e. ribosomes)
• Plasmid
• Pili

• Flagella
• Cell wall
• Endospores

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Cell Walls

• Eubacteria have an outer wall made of
  peptidoglycan
• Some have an additional covering of
  polysaccharides bound to lipids
• Chemical differences in cell wall determine which
  (if any) antibiotics will be effective

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Gram Staining

• Process that determines bacteria type, using two
  different stains and an alcohol wash
• Gram Positive (G)
• Has no outer covering OUTSIDE of the cell wall
• Stains a deep violet or purple
• Gram Negative (G-)
• Has a protective lipid outer covering OUTSIDE of
  the cell wall
• Stains a light pink or red color

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Bacterial Reproduction

• Binary Fission
• Splitting in two
• New cells are identical to the parent cell
  unless there is a mutation

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Bacterial Reproduction, cont.

• Conjugation
• Transfer of some genetic material from one
  bacteria to another through a bridge formed by
  pili
• Does not increase the number of bacteria, but it
  increases genetic possibilities

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Adapting to the Environment

• Endospores
• A thick internal wall that surrounds the DNA and
  a portion of the cytoplasm
• Makes it possible for bacteria to survive harsh
  conditions
• Drought Flood
• Extreme heat or cold

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Nutrition

• Autotrophs make their own food
• Photoautotrophs Photosynthesize (convert
  sunlight, CO2 and H2O into O2 and carbon
  molecules)
• Chemoautotrophs - Chemosynthesize (convert CO2
  into carbon molecules)

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Nutrition, cont.

• Heterotrophs
• Cannot make their own food
• Can be decomposers
• Can be parasitic

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Oxygen Requirements

• Obligate Aerobes
• Require constant supply of O2
• Obligate Anaerobes
• Require ABSENCE of O2
• Facultative Anaerobes
• Can live with or without O2

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Symbiotic Bacteria

• E. coli in human intestine
• E. coli makes Vitamin K which we need for blood
  clotting
• Rhizobium and legumes
• Nitrogen-fixing bacteria
• Bacteria converts atmospheric nitrogen (N2) into
  ammonia (NH3), a form of nitrogen that the plant
  can use.

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Viruses

• Means little poison in Latin
• Smaller than bacteria
• Nonliving
• Components
• Particles of nucleic acid (DNA or RNA)
• Capsid - protein coat

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Types of Viruses

• Viruses are specific to cells
• Viral proteins must bind to specific receptors on
  the surface of a cell and trick the cell into
  allowing the virus inside
• Plant viruses infect plant cells
• Animal viruses infect animal cells
• Bacteriophages infect bacteria cells

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Lytic Cycle (fast)

• Virus enters cell
• Makes copies of itself
• Causes cell to burst (lyse)
• Releases viruses to infect other cells
• This is a very FAST cycle
• COLD, INFLUENZA

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Lysogenic Cycle (slow)

• Virus enters cell
• The DNA of the host cell and the viral genetic
  information replicate indefinitely
• Can remain inactive for long periods of time, so
  you do not always know that the virus is there
• HIV, HERPES

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Retroviruses

• A virus that contains RNA as its genetic
  information.
• Produces DNA copies of its RNA
• Remain dormant before becoming active
• Ex. HIV Human Immunodeficiency Virus (causes
  AIDS)

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Viruses Dependence

• Viruses are nonliving, so they depend on living
  things for
• Growth replication
• Cellular Respiration (no mitochondria)
• Nutrition
• All other functions that occur in living things

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Diseases Caused by Bacteria Viruses
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Pathogens

• Disease-causing agents
• Conflict/relationship with host causes the
  disease

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Bacteria Diseases in Humans

• Louis Pasteur developed the germ theory of
  disease (bacteria cause disease)
• Bacteria cause problems by
• Damaging cells and tissues for food
• Releasing toxins that interfere with the hosts
  normal activities

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Using Cells for Food

• Mycobacterium tuberculosis
• destroys lung tissue
• Can enter blood stream and destroy other tissue
  in the body

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Releasing Toxins

• Streptococcus
• Strep throat
• Toxins can cause scarlet fever
• Corynebacterium diphtheria
• diptheria
• Toxins can cause breathing problems, heart
  failure, paralysis, and death

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Preventing/Killing Bacterial Diseases

• Vaccines
• Weakened or killed pathogen
• Stimulates the immune system
• Antibiotics
• Drugs that attack and destroy bacteria
• Penicillin and tetracycline
• Block the growth and reproduction of bacteria

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Bacterial Diseases in Animals

• Bacillus anthracis
• Anthrax usually affects sheep, but can be fatal
  to animals and humans
• Resistant spore can last for years

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Controlling Bacteria

• Sterilization
• High temperatures for long periods of time, kill
  bacteria
• Disinfectants
• Chemical solutions that kill pathogenic bacteria
• Antibacterial chemicals are added to soaps
• Food storage processing
• Refrigeration, boiling, frying and steaming,
  canning, chemical treatments (salt, vinegar)

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Viral Diseases in Humans

• Disrupt the bodys normal equilibrium
• Often target certain cells
• Cause cells to change growth or development
• Cannot be treated with antibiotics, but can be
  treated with antivirals
• Prevented with vaccines

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Viral Diseases in Humans

• Poliovirus
• Attacks nervous system and causes paralysis
• Human papillomavirus (warts)
• Abnormal cell growth on skin
• Smallpox
• Causes high fever, fatigue, head and back aches,
  and rash
• Virtually eliminated

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Viral Diseases in Animals

• Foot-and-mouth disease
• Affects cattle
• Rous sarcoma virus
• Infects chickens
• Disrupts normal controls over cell growth and
  division
• Causes tumors

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Viral Disease in Plants

• Damaging to plants because of the damage to the
  cell wall
• Tobacco mosaic virus
• Potato yellow dwarf virus
• Carried by leafhoppers
• Can destroy entire crops

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Viroids are virus-like particles

• Single-stranded RNA molecules that have no
  surrounding capsid
• Disrupt metabolism of plant cell
• Stunt growth of entire plant
• Seen in potatoes, tomatoes, apples and citrus
  fruit

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Prions are virus-like particles

• Protein infectious particles
• Contain no DNA or RNA, only protein
• Affect sheep, humans and other animals
• Forms protein clumps, which cause normal proteins
  to become prions
• Possible cause of mad cow disease and
  Creutzfeldt-Jakob disease