Bacteria and Actinobacteria Overview
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Questions and Answers

What fundamental characteristic is used to divide bacteria in GRAM STAINING?

  • Metabolic activity
  • Cell wall/membrane structure (correct)
  • Genetic material
  • Size and shape

    • Which type of bacteria stains purple in GRAM STAINING?

  • Rod-shaped
  • GRAM-positive (correct)
  • GRAM-negative
  • Spherical

    • What percentage of bacteria are estimated to be undescribed?

  • 90%
  • 50%
  • 79.9% (correct)
  • 30%

    • What is a primary source of biodiversity estimates for bacteria?

    <p>Genome-level data</p> Signup and view all the answers

    What effect can cell wall structure have on bacteria?

    <p>Affects environmental tolerance</p> Signup and view all the answers

    What is a significant role of Wolbachia spp. in biological processes?

    <p>Acts as a male killer in insects</p> Signup and view all the answers

    Which strain of E. coli is associated with contamination of meat and vegetables?

    <p>E. coli O157:H7</p> Signup and view all the answers

    Which disease is caused by Yersinia pestis?

    <p>Black Death</p> Signup and view all the answers

    What type of infection does the pneumonic plague refer to?

    <p>Respiratory infection</p> Signup and view all the answers

    What gastrointestinal issue is Helicobacter pylori highly correlated with?

    <p>Stomach ulcers</p> Signup and view all the answers

    What role do Actinobacteria play in agriculture?

    <p>They assist in organic matter decomposition.</p> Signup and view all the answers

    What characterizes the symbiotic relationship of Actinobacteria with plants?

    <p>They help plants by forming nodules filled with nitrogen-fixing bacteria.</p> Signup and view all the answers

    How are Actinobacteria relevant in bioremediation?

    <p>They metabolize contaminants such as heavy metals and oil.</p> Signup and view all the answers

    What is a significant feature of Firmicutes such as Bacillus Thuringiensis?

    <p>They produce toxic crystals under stress that affect insect digestion.</p> Signup and view all the answers

    What are the characteristics of Actinobacteria in relation to their cellular structure?

    <p>They are gram-positive prokaryotes.</p> Signup and view all the answers

    What is the primary characteristic of Cyanobacteria?

    <p>They are the only photosynthetic bacteria.</p> Signup and view all the answers

    Which Staphylococcus species is associated with multi-drug resistance?

    <p>Staphylococcus aureus</p> Signup and view all the answers

    Which bacteria are responsible for causing Lyme disease?

    <p>Borrelia burgdorferi</p> Signup and view all the answers

    What role do toxins produced by Cyanobacteria play in their ecology?

    <p>Reducing competition for resources</p> Signup and view all the answers

    Which of the following statements about Streptococcus is true?

    <p>Some species can only be pathogenic under specific conditions.</p> Signup and view all the answers

    What is a significant evolutionary transition that occurred in protists?

    <p>Unicellular to multicellular organisms</p> Signup and view all the answers

    Which of the following statements about protists is true?

    <p>Most protists are responsible for 80% of Earth's atmospheric O₂.</p> Signup and view all the answers

    What defines mixotrophs among protist species?

    <p>Organisms that utilize both photoautotrophy and chemoorganoheterotrophy.</p> Signup and view all the answers

    What role do decomposer protists play in their ecosystems?

    <p>They break down organic matter to recycle nutrients.</p> Signup and view all the answers

    Which of the following best describes the diversity of protists?

    <p>Protists are characterized by a lack of synapomorphies.</p> Signup and view all the answers

    What distinguishes photoautotrophs in terms of energy and carbon sources?

    <p>They use sunlight for energy and absorb $CO_2$ for carbon.</p> Signup and view all the answers

    Which type of organism relies on both sunlight and organic sources for energy and carbon?

    <p>Photoheterotroph</p> Signup and view all the answers

    Which of the following statements about chemoorganoheterotrophs is true?

    <p>They obtain energy and carbon exclusively from living or dead organisms.</p> Signup and view all the answers

    Which group of organisms is primarily classified as photoautotrophs?

    <p>Cyanobacteria and plants</p> Signup and view all the answers

    What is the main source of carbon for heterotrophs?

    <p>Living or dead organisms</p> Signup and view all the answers

    What process do phytoplankton use to produce oxygen?

    <p>Photosynthesis</p> Signup and view all the answers

    Which condition primarily leads to the occurrence of algal blooms in aquatic environments?

    <p>Abundant nitrogen and phosphorus</p> Signup and view all the answers

    What is the primary role of chloroplasts in phytoplankton?

    <p>Photosynthesis</p> Signup and view all the answers

    Which of the following is a characteristic of unicellular green algae?

    <p>Can exist as filamentous forms</p> Signup and view all the answers

    Which of the following describes the habitat of multicellular green algae?

    <p>Lives attached to a substrate</p> Signup and view all the answers

    What is the primary habitat of diatoms?

    <p>In freshwater and saltwater</p> Signup and view all the answers

    What is a key structural feature of diatoms?

    <p>They have a silica shell made of two halves</p> Signup and view all the answers

    What happens to diatoms when they die?

    <p>They sink and can become fossils</p> Signup and view all the answers

    Which of the following is NOT a commercial use of diatoms?

    <p>Biodegradable plastics</p> Signup and view all the answers

    How do diatoms contribute to aquatic food webs?

    <p>They are a primary food resource and habitat</p> Signup and view all the answers

    What type of organisms are choanoflagellates?

    <p>Unicellular protists</p> Signup and view all the answers

    What is a characteristic of dinoflagellates' flagella?

    <p>A longer flagellum is for movement and a shorter one for feeding</p> Signup and view all the answers

    Which phenomenon is caused by dinoflagellates?

    <p>Red tides</p> Signup and view all the answers

    What type of nutritional strategy do choanoflagellates utilize?

    <p>Chemoorganoheterotrophy</p> Signup and view all the answers

    What is the relationship between zooxanthellae and corals?

    <p>Mutualistic</p> Signup and view all the answers

    Which characteristic is a common feature of brown algae?

    <p>They are strictly marine and photoautotrophs.</p> Signup and view all the answers

    What role do red algae play in deep water coral reefs?

    <p>They provide habitats and food supporting biodiversity.</p> Signup and view all the answers

    Which of the following is NOT a characteristic of green algae?

    <p>They possess red pigments for deeper light absorption.</p> Signup and view all the answers

    What is the significance of holdfasts in brown algae?

    <p>They anchor the algae to substrates.</p> Signup and view all the answers

    What impact did the decline of sea otters have on kelp forests?

    <p>Decreased growth of kelp forests due to overpopulated sea urchins.</p> Signup and view all the answers

    Study Notes

    Bacteria

    • Are prokaryotic cells
    • Lack a membrane-bound nucleus
    • Most are unculturable
    • Classified by gram staining: positive (+) which stain purple or negative (-) which stain pink
    • Gram staining differentiates by cell wall/membrane structure
    • Peptidoglycan is the polysaccharide stained in a gram stain
    • The staining process shows how a cell recognizes food, toxins and what can enter or leave a cell
    • Gram staining also determines environmental tolerance and the use of antibiotics

    Actinobacteria

    • Are Gram-positive bacteria
    • Are important in agriculture, human health and forest ecosystems
    • Important in organic matter decomposition and nutrient recycling
    • Mutualistic: both organisms benefit
    • Symbiotic relationship with plants, forming nitrogen-fixing bacteria nodules on roots
    • Often found in biofilms with other bacteria, archaea, fungi, and algae
    • Can also form plaque on teeth, slime on pipes
    • Bioremediation can be used to clean up soil and water contamination

    Examples of Actinobacteria:

    • Arthrobacter globiformis (positive)
    • Geobacter metallireducens (negative)

    Firmicutes

    • Are Gram-positive
    • Example: Bacillus thuringiensis
    • Is an insecticidal bacteria that affects all arthropods
    • Produces toxic crystals when stressed
    • Kills insects trying to consume the crystals by dissolving their digestive system
    • Has resting stages called endospores in response to environmental stress

    Proteobacteria

    • Are Gram-negative
    • Example: Wolbachia spp.
    • Acts as a biological control, often called "the male killer"
    • Lives in the reproductive tract of female insects
    • Kills or sterilizes males, or feminizes them
    • Decreases populations

    Proteobacteria

    • Example: Escherichia coli (E. coli)
    • Is important for mammalian digestion
    • Found in sewage and associated with water pollution
    • Can be pathogenic and cause illness
    • Has many strains with vastly different traits associated with genetic differences
    • Example: E. coli O157:H7
      • Found in meat and veggie contamination

    Proteobacteria, Example: Yersinia pestis

    • Responsible for the Black Death/Plague
    • Spread by fleas on rats
    • Forms of the disease:
      • Bubonic plague: attacks lymph nodes, causes swelling ("bubos")
      • Black plague: blood-borne
      • Pneumonic plague: respiratory infection, airborne
    • All forms respond well to antibiotics

    Helicobacter pylori

    • Associated with the stomach/gastrointestinal tract
    • Strongly linked to stomach ulcers and stomach cancer

    Cyanobacteria

    • Are Gram-negative
    • Known as "blue-green algae"
    • The only photosynthetic bacteria
    • Abundant where nitrogen and phosphorus levels are high - causing algal blooms
    • Produces toxins that can be deadly to organisms
    • Toxins are used to protect against and reduce competition for resources

    Firmicutes

    • Example: Streptococcus
    • Causes respiratory and skin infections
    • Important for cheese making and yogurt production

    Firmicutes

    • Example: Staphylococcus aureus
    • Causes skin infections
    • Can be commensal but can become pathogenic
    • Can become MRSA (multi-drug-resistant Staphylococcus aureus)

    Spirochaeta

    • Are Gram-negative
    • Spiral or corkscrew-shaped cells
    • Example: Borrelia burgdorferi
    • Responsible for transmitting Lyme disease
    • Spreads by ticks and also transmitted by deer, rodents, mice
    • Climate affects disease transmission

    Metabolic Diversity

    • Determines how prokaryotes acquire energy and carbon for growth and reproduction
    • Major Types:
      • Photoautotrophs
      • Photoheterotrophs
      • Chemoorganoheterotrophs

    Photoautotrophs

    • Acquire energy from sunlight
    • Acquire carbon from the atmosphere/environment
    • Examples: cyanobacteria, protists, and plants

    Photoheterotrophs

    • Acquire energy from sunlight
    • Acquire carbon from living or dead organisms
    • Examples: some plants, protists, and prokaryotes

    Chemoorganoheterotrophs

    • Acquire energy from living or dead organisms
    • Acquire carbon from living or dead organisms
    • Examples: most eukaryotes and most heterotrophs

    Protists

    • The first eukaryotes
    • Have membrane-bound nuclei
    • Fossil record resembles green algae
    • Are very diverse
    • There are no synapomorphies (single trait linking them all together)
    • Some species are mixotrophs and use both photoautotrophy and chemoorganoheterotrophy
    • Major evolutionary steps:
      • prokaryote → eukaryote
      • unicellular → multicellular
      • asexual → sexual reproduction

    Protists

    • Have a huge size range (microscopic to huge)
    • Found in aquatic environments: freshwater, saltwater, blood
    • Also found in terrestrial environments

    Ecological Role

    • Critically important for food webs
    • Photoautotrophs (primary producers)
    • Chemoorganoheterotrophs: Predators, consumers, decomposers, and scavengers
    • Terrestrial protists

    Protists

    • Are pathogens and parasites (e.g., malaria, giardia, plant pathogens)

    Aquatic Protists: Photoautotrophs

    • Called "phytoplankton" (floating plants)
    • Highly abundant
    • Photosynthetic
    • Responsible for 80% of Earth's atmospheric O₂
    • Drive the photosynthesis process
    • CO2 + H2O + sunlight → O2 + sugars
    • Sugars are food for chemoorganoheterotrophs
    • Depend on chloroplasts (membrane-bound organelles)
    • Chloroplasts are filled with chlorophyll
    • Abundant blooms occur when conditions are right (abundant N & P; water temperature)

    Phytoplankton Blooms

    • Include protists + cyanobacteria
    • Related to eutrophication

    Green Algae

    • Unicellular or multicellular
    • Sea lettuce (Ulva spp) - marine
    • Chara spp - "skunkweed" - freshwater

    Diatoms

    • Highly abundant and diverse
    • Strictly aquatic
    • Unicellular
    • Floating or attached phytoplankton
    • Shell made of two halves (frustule)
    • Made of silica
    • Have spores and openings
    • Allow water flow and CO₂ uptake for photosynthesis
    • Considered a critical food resource at the base of many food webs

    Diatoms when they die

    • Sink to the bottom of lakes and oceans
    • Fossils that can be used to piece together past climates and species tolerances
    • Used commercially for many uses:

    Diatom Commercial Uses:

    • Diatomaceous earth: a ground silica from diatoms used for different purposes
    • Swimming pool/lab filters: for purification
    • Kitty litter: absorbent material
    • Toothpastes: abrasive for cleaning teeth
    • Polishes: as a polishing agent

    Choanoflagellates

    • Unicellular protists
    • Feed on phytoplankton, bacteria, and small invertebrates
    • Are chemoorganoheterotrophs
    • Active swimmers with flagella
    • Reproduce in colonies

    Dinoflagellates

    • Unicellular mixotrophs
    • Have two flagellae
    • A longer flagellum for movement
    • A shorter flagellum for feeding
    • Part of phytoplankton blooms
    • Cause Red Tides and bioluminescence
    • Some species are coral symbionts (zooxanthellae)
    • Enhance coral survival
    • Mutually beneficial relationship with coral

    Attached Aquatic Protists:

    • Green algae: unicellular, attached green algae and diatoms
    • Brown algae: large, attached, multicellular growth forms, strictly marine
    • Red Algae: multicellular photoautotrophs, with red pigments that absorb light at deeper depths

    Brown Algae

    • Have holdfasts: attach to substrate
    • Fronds: the main photosynthetic surface
    • Gas bladders: maintain buoyancy
    • Dominant in intertidal and nearshore habitats
    • Support biodiversity

    Red Algae

    • Important for deep water coral reefs
    • Support biodiversity in kelp forests
    • Keystone predator (sea urchins) can drastically impact kelp forests
    • Reintroducing keystone predators (sea otters) increased kelp forest growth

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    Description

    Explore the fascinating world of bacteria, focusing on their prokaryotic nature, gram staining, and the vital role of Actinobacteria in ecosystems. This quiz covers their classification, mutualistic relationships, and importance in agriculture and health. Test your knowledge about their structure, functions, and contributions to nutrient recycling.

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