Bacteria
-Prokaryotic Organisms
-prokaryotic=
-only prokaryotic organisms
-all bacteria are prokaryotic
-Formerly located in Kingdom: Monera
-Presently consists of 2 diff. Kingdoms:
Archaebacteria=
Eubacteria=
-Oldest life forms on earth (3.5 billions
yrs. from fossil data)
-Most simple organisms
-Most abundant organisms
-2.5 billion/gram of soil
-Major economic and health group as
both beneficial and harmful organisms.
-present in everything we eat, and on
everything we touch.
Cellular Characteristics
Cell Wall
-polysaccharide structure
-Cellulose type compound
-lipids & proteins
-2 types of cell walls as determined
by a process called Gram Staining.
-Gram-Positive Bacteria
-thick cell walls (cell takes up color of stain).
-less harmful bacteria.
-more susceptible to antibiotics.
-Gram-Negative Bacteria
-highly complex cell wall-contains lipopolysaccharide
-the lipopolysaccharide layer
often allows these bacteria to
develop resistance to many
types of bacteria.
-more harmful types of bacteria.
Bacterial Shapes
Three shapes or forms
1. Bacilli=rod shaped or straight
2. Cocci=spherical
3. Spirilla=Spirally coiled
-many adhere together in a mass like a colony.
Reproduction
Binary fission=cell divides in two.
Kingdom Archaebacteria
-most ancient bacteria/organism.
-a few are photosynthetic.
-most are chemosynthetic.
-use chemical sources of energy:
-Ammonia NH3
-Methane CH4
-Hydrogen Sulfide H2S
-occur in very harsh environments.
-3 Types
1. Methanogens -produce methane (CH4)
-entirely anearobic
-occur in swamps & marshes
(low oxygen environment).
-producers of “Swamp Gas”
2. Thermoacidophiles:
-occur in extremely hot or acidic
environments (hot springs).
-commonly use H2S as energy.
3. Halophiles:
-occur in very salty environments, such as the Great Salt Lake and the Dead Sea.
Kingdom Eubacteria
-evolutionary younger group of bacteria.
-cannot withstand harsh envronments.
-very diverse group.
1. Photosynthetic Bacteria
-contain chlorophyll
-important contributors to the available oxygen level.
-example group: Cyanobacteria
2. Nitrogen-Fixing Bacteria
-convert atmospheric N2 into a form that can be used by other organisms (NH3).
-many live symbiotically with legumes (members of Bean Family-Fabaceae).
3. Decomposing Bacteria
-common on all surfaces
-major contributor to soil humus.
4. Pathogenic Bacteria---disease causing bacteria
-examples of bacterial diseases
-typhoid fever
-dysentery
-cholera
-tetanus
-pneumonia
-tuberculosis
-Staphylococcus = hospital infections
-Toxic Shock Syndrome
-Sexually transmitted diseases
-Gonorrhea
-Syphilis--often fatal
-Chlamydia
-Lyme disease (Tick Ixodes)
Viruses
-very simple, primitive entities.
-smaller than bacteria.
-unable to reproduce themselves.
-How they reproduce...
-composed of proteins, and nucleic
acids.
-often in helical and rod or thread-like
appearances.
-See Figure
-infect all types of organisms
-usually very host-specific
-Bacteriophage=virus that infects
bacteria.
-viruses disrupt normal cellular function
thus causing a variety of diseases.
-smallpox
-chicken pox
-measles
-rubella (german measles)
-mumps
-influenza
-common colds
-flu
-rabies
-AIDS
-herpesvirus
-vaccination against viral infections