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Bacteria and Archaea. Chapter 27. Types of Bacteria and Archaebacteria. Bacteria and Archaea. Diverse, abundant, and ubiquitous Most of the microbes (microscopic organisms) are bacteria or archaea Virtually all are unnamed and undescribed

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bacteria and archaea3
Bacteria and Archaea
  • Diverse, abundant, and ubiquitous
  • Most of the microbes (microscopic organisms) are bacteria or archaea
  • Virtually all are unnamed and undescribed
  • The total number of individual bacteria and archaea alive today at ~5  1030
  • As much carbon in these cells as there is in all of the plants on Earth
bacteria and archaea4
Bacteria and Archaea
  • Bacteria and Archaea form two of the three domains of the tree of life
bacteria
Bacteria
  • Prokaryotic
  • Cell walls made of peptidoglycan
  • Plasma membranes
  • Distinct ribosomes
  • RNA polymerase
  • Can cause human disease
archaebacteria
Archaebacteria
  • Prokaryotic and unicellular
  • Call walls made of polysaccharides
  • Unique plasma membranes
  • Ribosomes and RNA polymerase similar to those of eukaryotes
  • No Known to cause human disease
extremophiles
Extremophiles
  • Bacteria or archaea that live in high-salt, high-temperature, low-temperature, or high-pressure habitats
  • Archaea are abundant forms of life in hot springs at the bottom of the ocean
    • Water at 300°C emerges and mixes with 4°C seawater
  • Enzymes that function at low temperature or high temperature are of commercial use
cyanobacteria
Cyanobacteria
  • No free molecular oxygen existed for the first 2.3 billion years of Earth's history
  • Cyanobacteria, were the first organisms to perform oxygenic photosynthesis
cyanobacteria9
Cyanobacteria
  • Responsible for a fundamental change in Earth’s atmosphere
    • From an atmosphere dominated by nitrogen gas and carbon dioxide to one dominated by nitrogen gas and oxygen
  • Certain species of cyanobacteria can fix nitrogen
  • Form close association

with plant roots

    • Symbiotic relationship
studying bacteria and archaebacteria
Studying Bacteria and Archaebacteria
  • Biologists use several research strategies to answer questions about these species
  • Nutrient enriched agar
  • Based on establishing a specific set of growing conditions per bacteria
  • Used to isolate new types of bacteria and archaea
studying bacteria and archaebacteria14
Studying Bacteria and Archaebacteria
  • Direct sequencing - strategy for documenting the presence of bacteria and archaea that cannot be grown in culture and studied in the laboratory
evaluating molecular phylogenies
Evaluating Molecular Phylogenies
  • A tree of life based on morphology had only two divisions: prokaryotes and eukaryotes
evaluating molecular phylogenies17
Evaluating Molecular Phylogenies
  • The tree of life based on ribosomal RNA sequences shows three domains—Archaea, Bacteria, and Eukarya—and is now accepted as correct
  • The first lineage to diverge from the common ancestor was the Bacteria
  • Archaea and Eukarya are more closely related to each other than to the Bacteria
diversity of bacteria
Diversity of Bacteria
  • Bacteria and Archaea have diversified into hundreds of thousands of distinct species
  • Overall patterns and themes help biologists make sense of the diversity
  • The sizes, shapes, and motility of Bacteria and Archaea can vary greatly
gram staining
Gram Staining
  • Gram staining distinguishes bacteria by the type of cell wall
bacterial reproduction
Bacterial Reproduction
  • Bacteria and archaea reproduce by fission
    • Splitting of cells
  • Bacterial cells can transfer copies of plasmids – extra-nuclear loops of DNA
  • During conjugation, a copy of a plasmid moves from one cell to a recipient cell
  • Conjugation tube is a morphological trait that is unique to bacteria and archaea
conjugation

F factor (plasmid)

Male (donor) cell

Bacterial chromosome

F factor startsreplication andtransfer

Plasmids

Plasmid completestransfer andcircularizes

Cell now male

Conjugation
metabolic diversity
Metabolic Diversity
  • Bacteria and Archaea produce ATP in three ways:
  • Phototrophs can use light energy. ATP is produced by cellular respiration.
  • Organotrophs oxidize reduced organic molecules. ATP is produced by cellular respiration or fermentation
metabolic diversity29
Metabolic Diversity
  • Lithotrophs oxidize inorganic molecules. ATP is produced by cellular respiration with the inorganic compound serving as the electron donor
  • Autotrophs manufacture their own carbon-containing compounds heterotrophs live by consuming them
cellular respiration variation in bacteria
Cellular Respiration Variation in Bacteria
  • In cellular respiration
    • a molecule with high potential energy serves as an electron donor and is oxidized
    • a molecule with low potential energy serves as a final electron acceptor and is reduced
    • The potential energy difference is converted into ATP
  • Bacteria and archaea can exploit a wide variety of electron donors and acceptors
cellular respiration variation in bacteria34
Cellular Respiration Variation in Bacteria
  • Fermentation is a strategy for making ATP without using electron transport chains
  • No electron acceptor is used; redox reactions are internally balanced
    • Lactic acid fermentation
    • Alcoholic fermentation
lineages of bacteria
Lineages of Bacteria
  • There are at least 14 major lineages (phyla) of bacteria
  • Spirochetes have a corkscrew shape and unusual flagella
  • Chlamydiales are spherical and very tiny
    • Live as parasites inside animal cells
lineages of bacteria37
Lineages of Bacteria
  • High-GC (guanine and cytosine) Gram-positive bacteria have various shapes
  • Many soil-dwelling species form mycelia (branched filaments)
lineages of bacteria38
Lineages of Bacteria
  • Cyanobacteria are autotrophic
  • Produce an abundance of oxygen and nitroge
  • Also produce many organic compounds, that feed other organisms in freshwater and marine environments
lineages of bacteria39
Lineages of Bacteria
  • Low-GC Gram-positive bacteria cause a variety of diseases including anthrax, botulism, tetanus, gangrene, and strep throat
  • Lactobacillus is used to make yogurt
lineages of bacteria40
Lineages of Bacteria
  • Proteobacteria cause Legionnaire’s disease, cholera, dysentery, and gonorrhea
  • Certain species can produce vinegars. Rhizobium can fix nitrogen
archaea lineages
Archaea Lineages
  • Archaea live in virtually every habitat, including extreme environments
  • Crenarchaeota are the only life-forms present in certain extreme environments, such as high-pressure, very hot, very cold, or very acidic environments
archaea lineages42
Archaea Lineages
  • Euryarchaeota live in high-salt, high-pH, and low-pH environments
  • Include the methanogens, which contribute about 2 billion tons of methane to the atmosphere each year