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Mader: Biology 8th Ed.Bacteria, and Archaea
Mader: Biology 8th Ed.
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OutlineProkaryotesBacteriaArchaea
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Mader: Biology 8th Ed.The ProkaryotesThe prokaryotes include
bacteria and archaea, which are fully functioning cells.A single
spoonful of earth can contain 1010 prokaryotes.Range in size from
1-10m in length and .7-1.5m in width.
Mader: Biology 8th Ed.
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Mader: Biology 8th Ed.Prokaryote StructureLack a eukaryotic
nucleus.Have outer cell wall containing peptidoglycan.Some move by
means of flagella.Lack membranous organelles.Contain nucleoid.May
have accessory ring of DNA (plasmid).
Mader: Biology 8th Ed.
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Mader: Biology 8th Ed.Flagella
Mader: Biology 8th Ed.
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Mader: Biology 8th Ed.Reproduction in ProkaryotesProkaryotes
reproduce asexually by means of binary fission.Conjugation occurs
between bacteria when the donor cell passes DNA to recipient cell
by way of sex pilus.
Mader: Biology 8th Ed.
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Mader: Biology 8th Ed.Binary Fission
Mader: Biology 8th Ed.
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When faced with unfavorable conditions, some bacteria form
endospores (spores inside the cells)
Mader: Biology 8th Ed.Transformation occurs when bacterium picks
up free pieces of DNA from other prokaryotes.Transduction occurs
when bacteriophages carry portions of bacterial DNA from one cell
to another.
Reproduction in Prokaryotes
Mader: Biology 8th Ed.
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Mader: Biology 8th Ed.Prokaryotic NutritionObligate anaerobes
are unable to grow in the presence of free oxygen. Ex. Bacteria
causing botulism, tetanusFacultative anaerobes are able to grow in
either the presence or absence of gaseous oxygen. Ex. E. coli
Mader: Biology 8th Ed.
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Autotrophic ProkaryotesPhotoautotrophs use solar energy to
reduce carbon dioxide to organic compounds.PhotosynthesisEx.
Cyanobacteria, green sulfur bacteria
Chemoautotrophs oxidize inorganic compounds (hydrogen gas,
hydrogen sulfide, ammonia) to obtain the necessary energy to reduce
O2 to an organic compound.Chemosynthesis
Mader: Biology 8th Ed.
Mader: Biology 8th Ed.
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Mader: Biology 8th Ed.CyanobacteriaCyanobacteria are
Gram-negative bacteria that photosynthesize.Believed to be
responsible for introducing oxygen into the primitive
atmosphere.Lack visible means of locomotion.Can live in extreme
environments.In association with fungi, form lichens.
Mader: Biology 8th Ed.
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Mader: Biology 8th Ed.Cyanobacteria
Mader: Biology 8th Ed.
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Mader: Biology 8th Ed.Heterotrophic ProkaryotesMost prokaryotes
are chemotrophs that take in organic nutrients.Aerobic saprotrophs
(detritivores) decompose most large organic molecules to smaller
molecules.Chemoheterotrophs involved in fermentation
May be free-living or symbiotic.Nitrogen fixation
Commensalism
Mader: Biology 8th Ed.
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Mader: Biology 8th Ed.The BacteriaBacteria can also be
classified in terms of their three basic shapes.Spiral (spirilli),
Rod (bacilli), and Round (cocci).
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Mader: Biology 8th Ed.The ArchaearRNA has a different sequence
of bases than rRNA of bacteriaUnusual lipids( glycerol linked to
branched chain hydrocarbonds) in plasma membrane; allow them to
function at high temperatures.Cell walls composed of
polysaccharides, others pure protein; others no cell wallsUnique
forms of metabolism (methanogenesis)Most are
chemoautotrophsMutualistic or commensalistic ; no parasites
Mader: Biology 8th Ed.
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Types of ArchaeaMethanogensFound in anaerobic
environmentsSwamps, marshes, intestines, compost pits,
landfillsProduce methane from hydrogen gas and carbon dioxide.
HalophilesRequire high salt concentrations for growth.Great Salt
Lake in Utah, Dead Sea, hypersaline soilChloride pumps that pump
chloride inside the cellsSynthesize ATP in the presence of
light
Mader: Biology 8th Ed.
Mader: Biology 8th Ed.
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ThermoacidophilesReduce sulfides and survive best at
temperatures above 80oC. To 105oCHot springs, geysers, submarine
thermal vents, around volcanoesGrow in acidic sulfates at pH
1-2.
Mader: Biology 8th Ed.
Mader: Biology 8th Ed.
