Download Understanding Our Environment

Kingdom Bacteria, Kingdom Archaea,
and Viruses
Outline
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Cellular Detail and Reproduction of Bacteria
Classification of Bacteria
Kingdom Bacteria
 Phylum Bacteriophyta
- Class Bacteriae
- Class Cyanobacteriae
- Class Prochlorobacteriae
Kingdom Archaea
Viruses
Features of Kingdoms Bacteria and Archaea
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All have prokaryotic cells.
Nutrition is primarily by the absorption of food in
solution through the cell wall.
Reproduction is predominately asexual, by means
of fission.
More than 90% are either harmless or beneficial to
humans.
Motility
 Most are nonmotile
 Some posses bacterial flagella
 Others move by gliding motion
Cellular Detail and Reproduction of Bacteria
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Plasma folds and other membranes
apparently perform some of the functions of
the organelles of eukaryotic cells.
Plasmids may be present.
 Replicate independently of large DNA
molecule.
Mitosis does not occur.
 Internal reorganization of material during
which two DNA molecules migrate to
opposite ends of the cell.
Fig. 17.1
Fig. 17.2
Cellular Detail and Reproduction of Bacteria
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Three Forms of Genetic Recombination
 Conjugation
- DNA transferred from donor cell to
recipient cell.
 Transformation
- Living cell acquires DNA fragments
released by dead cells.
 Transduction
- DNA fragments carried from one cell to
another by viruses.
Fig. 17.3
Classification of Bacteria
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Most bacteria are less than 2 or 3 micrometers in
diameter, the smallest being 0.15 micrometers.
Occur primarily in three forms:
 Cocci - Spherical or Elliptical
 Bacilli - Rod shaped or Cylindrical
 Spirilla - Helix or Spiral
Bacteria are classified based on a reaction to a dye
into:
Gram positive
Gram negative
Copyright © McGraw-Hill Companies
Permission Required for Reproduction or Display
Copyright © McGraw-Hill Companies
Permission Required for Reproduction or Display
Copyright © McGraw-Hill Companies
Permission Required for Reproduction or Display
Kingdom Bacteria - The True Bacteria
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Phylum Bacteriophyta
 Class Bacteriae
 Have muramic acid in their cell walls and have different
RNA bases, metabolism, and lipids than archaebacteria
- Unpigmented, Purple, and Green Sulfur Bacteria.
 Most are heterotrophic (cannot synthesize their
own food and therefore depend on other
organisms for it).
 Majority of heterotrophic bacteria are saprobes
(living organisms that obtain their food from
non-living organic matter).
 Some are parasites (depend on living
organisms for their food).
Kingdom Bacteria - The True Bacteria
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Some are Autotrophic (like higher plants, can synthesize organic
compounds from simple inorganic compounds by photosynthesis)
e.g. cyanobacteria (blue green bacteria) and chloroxybacteria
produce oxygen.
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Some autotrophic bacteria such as purple sulfur, purple non-sulfur
and green sulfur bacteria photosynthesize without producing oxygen.
They appear purplish or red to brown because the presence of a
mixture of greenish, yellow, and red pigments. Their greenish
pigment is called bacteriochlorophyll and is very similar to chloropyll
a of higher plants. No plastids in bacteria and their pigments are
located in the plasma membrane.
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Purple sulfur bacteria use H2S instead of H2O in photosynthesis:
CO2 + 2H2S -------------------------- (CH2O) + H2O + 2S
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Purple non-sulfur bacteria use organic molecules instead of H2S.
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Green sulfur bacteria used H2S but their green pigment is chlorobium
chlorophyll which differs significantly from chlorophyll a of higher
plants.
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Some are Chemautotrophic i.e. get their energy by oxidation or
reduction of various compounds such as NH3, H2S, and Fe++
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Examples: Iron, Sulfur, and Hydrogen Bacteria
Iron bacteria convert soluble compounds of iron to insoluble
substances that accumulate as deposits (e.g. in water pipes).
Sulfur bacteria convert H2S to elemental sulfur and sulfur to
sulfate.
Hydrogen bacteria (in soils) use molecular hydrogen produced
from anaerobic bacteria and nitrogen-fixing bacteria.
Kingdom Bacteria - The True Bacteria
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Human Relevance of Class Bacteriae
 Composting
- Allow bacteria to decompose organic waste.
 Diseases
- Plant diseases caused by bacterial pathogens
cause American farmers losses of more than $4
billion per year.
- Many human and animal diseases are cause
by bacteria. Several modes of transmission of
bacteria have been identified.
Kingdom Bacteria - The True Bacteria
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Modes of Access
 Contamination of Food and Drink
- Salmonella
- Legionnaire Disease
- Botulism
 Direct Contact
- Syphilis and Gonorrhea
- Anthrax
Kingdom Bacteria - The True Bacteria
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Modes of Access
 Wounds
- Tetanus and Gangrene
 Insect Bites and Other Organisms
- Bubonic Plague
- Tularemia
- Rickettsias
- Mycoplasmas
- Lyme Disease
Koch’s Postulates
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Rules for proving a particular microorganism
is the cause of a particular disease.
 Microorganism must be present in all
cases of the disease.
 Microorganism must be isolated from the
victim in pure culture.
Koch’s Postulates
Microorganisms from the pure culture must
be able to infect hosts.
 Microorganism must be isolated from the
experimentally-infected host and grown in
pure culture for comparison with the
original culture.
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True Bacteria Useful to Humans
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Insecticide
 Bacillus thuringiensis and Bacillus popilliae
Bioremediation
 Explosives
 Petroleum
Vision
 Rhodopsin production
Fig. 17.9
True Bacteria Useful to Humans
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Dairy Products
 Cheese, yogurt
Human Health
 Lactobacillus acidophilus aid in digestion
 When used with antibiotics Lactobacillus
acidophilus are used to control female
yeast infections
Industrial Uses
 Photographic film
 Acetone
Class Cyanobacteria
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The Blue Green Algae
 Distinctions between traditional bacteria and
cyanobacteria.
- Cyanobacteria have chlorophyll a (which is
found in higher plants) and oxygen is
produced when they undergo photosynthesis.
- Cyanobacteria contain blue phycocyanin and
red phycoerythrin pigments known as
phycobilins.
- Cyanobacteria can both fix nitrogen and
produce oxygen.
Class Cyanobacteria
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Form, Metabolism, and Reproduction
 Cells in about half of the approximately 1,500
species are blue-green in color.
 Produce a nitrogenous food reserve called
cyanophycin.
 In the common genera Nostoc and Anabaena,
nitrogen-fixing cells are called heterocysts. Also,
thick-walled cells are produced and are known
as called akinetes (resist freezing and other
adverse conditions).
 Do not produce gametes or zygotes and do not
undergo meiosis.
Fig. 17.11
Class Cyanobacteria
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Human Relevance
 Included among the many aquatic and
photosynthetic organisms at the bottom of
various food chains.
 Often become abundant in bodies of fresh water
in warmer months.
- Algal Blooms
 Swimmers Itch cause by a toxin produced by
Lyngbya, a cyanobacteria. Same toxin has been
demonstrated to supress leukemia and other
types of cancer.
 Nitrogen Fixation
Class Prochlorobacteriae
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The Prochlorobacteria
 Have chlorophyll a and b of higher plants,
but no trace of the phycobilin accessory
pigments of cyanobacteria.
- Adds to theory that chloroplasts may
have originated from cells living within
the cells of other organisms.
Fig. 17.13
Kingdom Archaea
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One of two distinct lines of most primitive
organisms.
 Metabolism is fundamentally different from
other lines of bacteria.
Methane Bacteria
 Killed by oxygen and active only under
anaerobic conditions.
- Energy derived from the generation of
methane gas from carbon dioxide and
hydrogen.
Kingdom Archaea
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Salt Bacteria
 Metabolism enables these bacteria to
thrive under extreme salinity.
- Carry on simple photosynthesis with the
aid of bacterial rhodopsin.
Sulfolobus Bacteria
 Metabolism allows these species to thrive
at very high temperatures.
- Also found in acidic hot springs.
Human Relevance of Archaebacteria
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Methane has a high octane level.
 Given off by bacteria as they digest
organic wastes in the absence of oxygen.
- In a methane digester, sludge makes an
excellent fertilizer.
Viruses
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Consist of a nucleic acid core surrounded by
a protein coat.
 Separated first according to the DNA or
RNA.
- Next grouped according to size and
shape, nature of protein coats, and
number of identical structural units in
their cores.
 Bacteriophages - Viruses that attack
bacteria.
Phage Virus
Viral Reproduction
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Viruses can only replicate at the expense of
their host cells.
 Attach to susceptible cell.
- Penetrate to cell interior.
 DNA or RNA dictates synthesis of new
molecules.
 New viruses released from host cell.
 Some can mutate very rapidly.
- Immunity becomes more difficult.
Human Relevance of Viruses
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Annual loss in work time due to common cold
and influenza viruses alone amount to
millions of hours.
 Immunizations have dramatically
decreased incidence of many viruses such
as German Measles, Mumps, and Chicken
Pox.
AIDS
 Retrovirus
- Evolves extremely quickly.
Viroids and Prions
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Viroids - Circular strands of RNA that occur in
the nuclei of infected plant cells.
 Transmitted from plant to plant via pollen,
ovules, or machinery.
- Cause more than a dozen plant
diseases.
Prions - Appear to be particles of protein that
cause diseases of animals and humans.
 No nucleic acids yet detected.
Review
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Cellular Detail and Reproduction of Bacteria
Classification of Bacteria
Kingdom Bacteria
 Phylum Bacteriophyta
- Class Bacteriae
- Class Cyanobacteriae
- Class Prochlorobacteriae
Kingdom Archaea
Copyright © McGraw-Hill Companies Permission Required for Reproduction or Display