Chapter 21 Viruses and Bacteria

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Chapter 21 Viruses and Bacteria

• High School Biology Class

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Kingdom Monera

• Bacteria are classified into two kingdoms
• Eubacteria
• Archeabacteria
• Virus are NOT in any kingdom because most
  scientists do not consider them to be living
  organisms.

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What is a Bacteria?

• Bacteria are one celled prokaryotes (have no
  nucleus or organelles) that cover nearly every
  square centimeter of the planet (can live in
  extremely harsh environments).

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Bacteria Background

• 1. Bacteria are the most numerous organisms on
  Earth and the most ancient - they were probably
  the first forms of life (2.5 bya).
• 2. Bacteria (like viruses) are very small and
  difficult to see.

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Bacteria Background

• 3. Bacteria are classified according to their
  ribosomal RNA sequences, cell wall structures,
  and how they obtain energy.
• 4. Scientists hypothesize that all eukaryotic
  organisms evolved from bacteria by the Theory of
  Endosymbiosis.

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Types of Bacteria

• Scientists have found that there are two vastly
  different types of bacteria
• A. The more ancient bacteria are classified in
  the Kingdom Archaebacteria. 
• B. The bacteria that we refer to as germs" are
  classified in the Kingdom Eubacteria.

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Gram-Staining Process

• Some bacteria have peptidoglycan in their cell
  walls while others do not.
• Scientists use this fact as a way to separate the
  bacteria kingdoms.

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Gram-Staining Process

• The technique involves staining bacteria with a
  purple dye (Crystal Violet), iodine, and then
  rinsing with alcohol. Finally, they are
  re-stained with a pink dye (Safarinin).

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A. Kingdom Archaebacteria

• Ancient bacteria live in extremely harsh
  environments like digestive tracts, hot springs,
  deep-sea oceanic vents, and very salty habitats.
• Archaebacteria - have no peptidoglycan in their
  cell walls (pink color).

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A. Kingdom Archaebacteria

• Archaebacteria are divided into three groups
• Methanogens
• (convert H2 and CO2 into methane)
• Thermoacidophiles
• (convert hot, acidic gases into energy)
• Halophiles
• (convert salty water into ATP)

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B. Kingdom Eubacteria

• True bacteria are the largest group of bacteria
  with many different varieties.
• Eubacteria - have peptidoglycan in their cell
  walls (purple color).
• Although many of these bacteria are thought of as
  germs only a few actually produce diseases.

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B. Kingdom Eubacteria

• Eubacteria are divided into five groups
• Proteobacteria
• Gram-positive Eubacteria
• Cyanobacteria (made the Earths oxygen)
• Spirochetes
• Chlamydias

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Bacteria Sizes

• Most bacteria are about 1 micrometer or 10 times
  smaller than eukaryotic cells.

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Bacteria Shapes

• Bacteria can be three different shapes   
• 1) Rod-shaped are called Bacilli.
• 2) Sphere-shaped are called Cocci.
• 3) Spiral-shaped are called Spirilla.

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Bacteria Clustiering (Groupings)

• Bacteria can be divided into three different
  groupings
• 1) Diplo a prefix used to indicate pairs of
  cells.
• 2) Strepto a prefix used to indicate filaments.
  
• 3) Staphylo a prefix used to indicate clusters.

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Bacteria Cell Walls

• Gram-Positive - have peptidoglycan in their cell
  walls
• (Eubacteria)
• Gram-Negative DO NOT have peptidoglycan in
  their cell walls

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Bacteria Movements

• Flagella long whiplike structure to help move
  the bacteria.
• Pili short, thick hair that can attach to
  surfaces.
• Slimelike Fluids Myxobacteria produce a layer
  of slime and then glide through it.
• Nonmotile stay in one place and do not move on
  their own.

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Bacteria Energy

• Most bacteria are heterotrophs (get energy by
  eating food).
• Some are autotrophs and can make their own food
  (sunlight).

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Bacteria Energy

• Most bacteria are obligate aerobes (need oxygen
  to live).
• Some are obligate anaerobes (cannot live in the
  presence of oxygen).
• Few are facultative anaerobes (do not need oxygen
  but can live in it.)

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Bacteria Growth

• Most bacteria reproduce by a process called
  binary fission.
• This occurs in two steps
• a) DNA replicates (copies)
• b) Cell divides
• This is asexual reproduction and can occur in 20
  minutes.

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Bacteria Diseases

• There are two ways bacteria can cause diseases
• Breakdown and destroy living cells.
• Release toxins (poisons) in cells that cause them
  to malfunction.

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Bacteria Diseases
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Bacteria Prevention

• Once again the best defense against bacteria is
  to prevent their infection.
• The best way to do this is to stimulate the
  bodies immune system by using a vaccine.

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Bacteria Infections

• If a bacteria infection does occur there are
  medications (antibiotics) that can help fight the
  bacteria.
• In 1928, a British bacteriologist, Alexander
  Fleming discovered the first antibiotic
  penicillin.

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Bacteria Infections
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Antibiotic Concerns

• 1. When a population of bacteria is exposed to an
  antibiotic, the most susceptible bacteria die.  A
  few mutant bacteria that are resistant to the
  antibiotic may continue to grow.
• 2. A resistant population then grows from these
  mutant bacteria.
• - (natural selection?)

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Antibiotic Concerns

• 3. These new population are antibiotic-resistant. 
  
• 4. Consequently, many diseases that were once
  easy to treat are becoming more difficult to
  cure.

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Bacteria Benefits

• Bacteria affect our lives in many positive ways
• Bacteria are used in Sewage Treatment.
• As decomposers they break down the remains of
  organic matter in dead plants and animal wastes. 
  
• They are recyclers who return nutrients back to
  the environment.

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Bacteria Benefits

• 2. Bacteria are useful in food production. 
• Bacteria help us make buttermilk, sour cream,
  yogurt, cottage cheese, sauerkraut, and pickles.

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Bacteria Benefits

• 3. Bacteria are also used in industrial chemical
  production. 
• They produce organic chemicals and fuels.
• Used in the mining of minerals.
• Byproducts used as insecticides.

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Bacteria Benefits

• 4. Bacteria are used to help clean up
  environmental disasters.
• Cleaned up chemical and oil spills caused by
  humans.

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Any Questions?

• I don't know everything. I just do everything.
• --Toni Morrison
• I have no riches but my thoughts. Yet these are
  wealth enough for me.
• --Sara Teasdale