Prokaryotes - Monera - Biodiversity
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Questions and Answers

What is the primary way pathogenic bacteria cause disease?

  • By multiplying uncontrollably in tissues
  • By altering the host's immune system
  • By releasing exotoxins or endotoxins (correct)
  • By invading host cells directly
  • What is the role of horizontal gene transfer in pathogenic bacteria?

  • It improves nutrient absorption in bacteria
  • It increases the speed of bacterial reproduction
  • It enhances bacterial resistance to antibiotics
  • It spreads genes associated with virulence (correct)
  • Which bacterium is commonly used in gene cloning?

  • Thermus aquaticus
  • Agrobacterium tumefaciens
  • Escherichia coli (correct)
  • Staphylococcus aureus
  • What is bioremediation primarily used for?

    <p>To remove pollutants from the environment (B)</p> Signup and view all the answers

    Which statement about endotoxins is true?

    <p>They are released only when bacteria die (B)</p> Signup and view all the answers

    What distinguishes prokaryotes from eukaryotes?

    <p>Prokaryotes lack a nucleus. (D)</p> Signup and view all the answers

    Which of the following best describes the size of most prokaryotic cells?

    <p>They have diameters of 0.5 – 5 µm. (D)</p> Signup and view all the answers

    In what environments can prokaryotes thrive?

    <p>In extreme conditions including acidic, salty, or hot environments. (C)</p> Signup and view all the answers

    What is the primary function of a capsule in prokaryotes?

    <p>To protect against dehydration and immune attacks (D)</p> Signup and view all the answers

    What are the two primary lineages of prokaryotes?

    <p>Bacteria and Archaea. (C)</p> Signup and view all the answers

    Which of the following is NOT a common shape of prokaryotes?

    <p>Square (squarili). (D)</p> Signup and view all the answers

    Which structures are primarily responsible for the motility in prokaryotes?

    <p>Flagella (B)</p> Signup and view all the answers

    What type of DNA structure do prokaryotes possess?

    <p>Circular with fewer proteins (A)</p> Signup and view all the answers

    What is the primary method of reproduction for prokaryotes?

    <p>Binary fission (D)</p> Signup and view all the answers

    How do fimbriae assist prokaryotes?

    <p>They allow adherence to surfaces or to each other (A)</p> Signup and view all the answers

    Which process involves a prokaryotic cell taking up foreign DNA from its environment?

    <p>Transformation (A)</p> Signup and view all the answers

    What term describes the movement of genes between bacteria through viruses?

    <p>Transduction (B)</p> Signup and view all the answers

    What is a characteristic of endospores in prokaryotes?

    <p>They are resistant structures developed under nutrient deficiency (B)</p> Signup and view all the answers

    What is one of the main contributors to genetic diversity in prokaryotes?

    <p>Horizontal gene transfer (C)</p> Signup and view all the answers

    What type of movement does positive taxis refer to in prokaryotes?

    <p>Movement towards a favorable stimulus (A)</p> Signup and view all the answers

    What defines the presence of a nucleus in eukaryotic cells compared to prokaryotic cells?

    <p>Eukaryotic cells have a defined nucleus containing their DNA (A)</p> Signup and view all the answers

    Which of the following accurately describes prokaryotic generation times?

    <p>Short, often ranging from 20 minutes to a few hours (C)</p> Signup and view all the answers

    Which of the following organisms is likely to be antibiotic resistant?

    <p>Gram-negative bacteria (C)</p> Signup and view all the answers

    In prokaryotes, what is the effect of rapid reproduction on mutations?

    <p>It causes mutations to accumulate quickly over time (A)</p> Signup and view all the answers

    Which of these accurately describes the process of conjugation in prokaryotes?

    <p>Sharing of genetic material directly through cell contacts (A)</p> Signup and view all the answers

    What is the primary reason prokaryotes evolve rapidly?

    <p>Frequent genetic recombination and rapid reproduction (C)</p> Signup and view all the answers

    What is a common pathogenic parasite mentioned in the content?

    <p>Treponema pallidum (B)</p> Signup and view all the answers

    What role do chemoheterotrophic prokaryotes primarily serve in ecosystems?

    <p>Decomposers (D)</p> Signup and view all the answers

    Which type of ecological interaction is characterized by one organism benefiting while the other is neither helped nor harmed?

    <p>Commensalism (D)</p> Signup and view all the answers

    Which group of bacteria is known for their role in antibiotic production?

    <p>Actinomycetes (D)</p> Signup and view all the answers

    What significant impact do prokaryotes have on plant growth?

    <p>They increase the availability of essential nutrients. (D)</p> Signup and view all the answers

    Which characteristic distinguishes cyanobacteria from other bacteria?

    <p>Ability to perform oxygen-generating photosynthesis (D)</p> Signup and view all the answers

    What is one way that mutualistic bacteria in human guts benefit their host?

    <p>By digesting food that the host cannot break down (D)</p> Signup and view all the answers

    Which of the following correctly describes proteobacteria?

    <p>Diverse group of gram-negative bacteria with various lifestyles (D)</p> Signup and view all the answers

    What is the primary function of a sex pilus in bacteria?

    <p>To transfer genetic material (B)</p> Signup and view all the answers

    Which type of prokaryote is poisoned by oxygen and relies on fermentation?

    <p>Obligate anaerobes (C)</p> Signup and view all the answers

    What significant classification change occurred due to molecular systematics?

    <p>Prokaryotes were split into bacteria and archaea (C)</p> Signup and view all the answers

    Which of the following statements is true about methanogens?

    <p>They produce methane as a waste product (A)</p> Signup and view all the answers

    What characteristic is NOT associated with chlamydias?

    <p>They have a gram-positive cell wall (A)</p> Signup and view all the answers

    What environment do extremophiles most likely inhabit?

    <p>Highly saline or extremely hot environments (B)</p> Signup and view all the answers

    Which prokaryotic group includes organisms that predominantly rely on fermentation?

    <p>Methanogens (C)</p> Signup and view all the answers

    What is the role of facultative anaerobes in relation to oxygen?

    <p>They can survive with or without oxygen (B)</p> Signup and view all the answers

    Flashcards

    Prokaryotes

    Microscopic organisms lacking a nucleus, most are single-celled.

    Bacteria & Archaea

    Two lineages that are prokaryotic and make up Kingdom Monera.

    Bacterial Shapes

    Cocci (spherical), Bacilli (rod-shaped) are common shapes among bacteria.

    Prokaryotic Size

    Typically smaller (0.5-5 µm) than eukaryotic cells (10-100 µm).

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    Prokaryotic Diversity

    Prokaryotes thrive in a wide variety of environments.

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    Capsule vs. Slime Layer

    Both are sticky outer layers on prokaryotes, but capsules are denser and well-defined, while slime layers are less organized.

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    Prokaryotic Adaptation: Capsule & Slime Layer

    Capsules and slime layers help prokaryotes adhere to surfaces, resist drying out, and even evade host immune systems.

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    What are Endospores?

    Tough, multi-layered structures formed by some prokaryotes when they lack essential nutrients, helping them survive harsh conditions.

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    Fimbriae vs. Pili

    Both are hair-like appendages, but fimbriae help prokaryotes attach to surfaces, while pili help them pull two cells together for DNA transfer.

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    What is Taxis?

    Directed movement of prokaryotes towards or away from a stimulus.

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    Flagella in Prokaryotes

    Flagella are whip-like structures that propel prokaryotes. They have a motor, hook, and filament.

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    Prokaryotes vs. Eukaryotes: Compartmentalization

    Prokaryotes lack complex compartmentalization compared to eukaryotes, although they may have specialized membranes for metabolic functions.

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    Prokaryotes vs. Eukaryotes: DNA

    Prokaryotes have circular chromosomes with fewer proteins compared to the linear chromosomes with more proteins in eukaryotes.

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    Internal Organisation of Prokaryotes

    Prokaryotes have specialized membranes, often infoldings of the plasma membrane, to perform metabolic functions. Examples include respiratory membranes and thylakoid membranes in photosynthetic prokaryotes.

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    Prokaryotic Reproduction

    Prokaryotes reproduce asexually through binary fission, where one cell divides into two identical daughter cells. This process is rapid, allowing for rapid population growth in favorable environments.

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    Key Features of Prokaryotic Reproduction

    Prokaryotes reproduce quickly through binary fission, have short generation times, and evolve rapidly due to their small size and efficient reproduction.

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    Genetic Diversity in Prokaryotes

    Prokaryotes exhibit high genetic diversity due to rapid reproduction, mutations, and genetic recombination.

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    Mutations in Prokaryotes

    While mutation rates during binary fission are low, the rapid rate of reproduction allows mutations to accumulate quickly in a population.

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    Genetic Recombination

    The combining of DNA from two sources, called genetic recombination, contributes to diversity in prokaryotes. This occurs through transformation, transduction, and conjugation.

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    Horizontal Gene Transfer

    The movement of genes among individuals from different species, called horizontal gene transfer, further increases prokaryotic diversity.

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    Transformation

    Transformation is the process where a prokaryotic cell takes up and incorporates foreign DNA from the surrounding environment.

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    What is conjugation?

    The process of transferring genetic material between prokaryotic cells that are temporarily joined.

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    What is the role of a sex pilus in conjugation?

    A sex pilus is a structure that connects two prokaryotic cells, allowing for the transfer of genetic material during conjugation.

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    What is an obligate aerobe?

    A prokaryote that absolutely requires oxygen for cellular respiration.

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    What is an obligate anaerobe?

    A prokaryote that cannot tolerate oxygen and uses fermentation or anaerobic respiration for energy.

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    What is a facultative anaerobe?

    A prokaryote that can survive with or without oxygen.

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    What is molecular systematics?

    Using genetic analysis to investigate the evolutionary relationships between organisms.

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    Extreme Halophiles

    Archaea that thrive in extremely salty environments.

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    Extreme Thermophiles

    Archaea that thrive in very hot environments.

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    Pathogenic Prokaryotes

    Prokaryotes that cause diseases in humans.

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    Exotoxins

    Toxic proteins secreted by some bacteria that cause disease even when the bacteria are not present.

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    Endotoxins

    Toxic components of bacterial cell walls that are released only when the bacteria die.

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    Bioremediation

    Using organisms, like bacteria, to clean up pollutants in the environment.

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    Transgenic Plants

    Plants genetically modified to carry genes from other organisms, often using bacteria.

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    Spirochetes

    A group of spiral-shaped bacteria, many live freely, but some are known for causing serious diseases.

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    Cyanobacteria

    Photosynthetic bacteria, essential for generating oxygen, can form chains or be single-celled.

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    Gram-positive bacteria

    Bacteria with a thick peptidoglycan layer in their cell wall, many are decomposers or produce antibiotics.

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    Proteobacteria

    A diverse and large group of bacteria, they can use various energy sources and are found in many environments.

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    Prokaryotic Roles: Chemical Recycling

    Prokaryotes play a vital role in breaking down dead organisms and waste products, allowing nutrients to be reused.

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    Prokaryotic Symbiosis: Mutualism

    A relationship where both organisms involved benefit from each other.

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    Prokaryotic Symbiosis: Parasitism

    A relationship where one organism benefits at the expense of another, often causing harm.

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    Mutualistic Bacteria in Humans

    Beneficial bacteria in our gut help digest food that our body can't, playing a crucial role in our health.

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    Study Notes

    Prokaryotes - Monera - Biodiversity

    • Prokaryotes are the first organisms on Earth
    • They lack a nucleus and are mostly unicellular
    • Most prokaryotic cells are 0.5-5μm in diameter, much smaller than eukaryotic cells (10-100μm) — exception: Thiomargarita namibiensis (750μm)
    • Prokaryotes are smaller and simpler than eukaryotes, but make up for it in numbers
    • They thrive in almost all environments, including extreme conditions (acidic, salty, cold, hot) that are unsuitable for most other organisms
    • Divided into two lineages: Bacteria and Archaea
    • Both are prokaryotes, belonging to Kingdom Monera

    Features of Prokaryotes

    • Shape:

      • Spherical (cocci): single, pairs, chains, clusters
      • Rod-shaped (bacilli): single, chains
      • Spiral: comma-like, loose coils, corkscrew-shaped -Exceptions: Flat and square-shaped Haloquadratum walsbyi
    • Cell-surface structure:

      • Cell wall maintains cell shape, protects from bursting in hypotonic environments for nearly all prokaryotes
      • Eukaryotic cell walls are made of cellulose or chitin
      • Bacterial cell walls contain peptidoglycan, a network of sugar polymers cross-linked by polypeptides
      • Archaeal cell walls contain a variety of polysaccharides and proteins but lack peptidoglycan
      • Gram-staining differentiates bacteria based on the amount of peptidoglycan in the cell wall: -Gram-positive bacteria have a thick peptidoglycan layer and stain purple -Gram-negative bacteria have a thin peptidoglycan layer and an outer membrane and stain red
      • Capsule: sticky layer of polysaccharide or protein around the cell wall for protection and adherence
      • Slime layer: a less organized, sticky layer, which also helps with adherence.
      • Endospores: tough, multi-layered resistant cells formed by some when nutrients are scarce
    • Motility:

      • Some prokaryotes use flagella for movement
      • Flagella are motor, hook, and filament parts
    • Internal organization and DNA:

      • Simpler than those of eukaryotes
      • No membrane-enclosed organelles
      • Less DNA (circular chromosome with few proteins)
      • Often possess plasmids (small rings of DNA)
      • DNA lies in a nucleoid area within the cell.
      • Specialised metabolic membranes (infoldings of the plasma membrane) for different functions
    • Reproduction:

      • Binary fission: a single cell divides into two identical cells
      • Rapid reproduction rates allow for quick adaptations
    • Mode of Nutrition:

      • Autotrophs make their own food: -Photoautotrophs use light -Chemoautotrophs use inorganic molecules,
      • Heterotrophs consume organic compounds as food: -Photoheterotrophs use light -Chemoheterotrophs consume organic molecules.

    Factors Influencing Genetic Diversity

    • Prokaryotes show substantial genetic variation
    • Main factors:
      • Rapid reproduction
      • Mutation
      • Genetic recombination

    Genetic Recombination

    • Combining DNA from different sources
    • Key methods include: -Transformation -Transduction -Conjugation

    Roles of Prokaryotes in the Biosphere

    • Chemical Recycling: -Decomposers break down dead organisms and waste products
      • Increase the availability of nitrogen, phosphorus, and potassium for plant growth
    • Ecological Interactions: -Symbiosis (live in close contact) -Mutualistic: both benefit -Commensalism: one benefits, the other is unaffected -Parasitic: one benefits, the other is harmed, but not killed; Pathogens are parasitic microorganisms that cause disease
    • Impact on humans: -Mutualistic: live in the human gut, aid in digestion -Pathogenic: cause disease; many diseases are caused by prokaryotes; Toxins cause disease (exotoxins released by the organism even if it is dead, endotoxins released by cell lysis)

    Prokaryotes in Research & Technology

    • Used for DNA technology like gene cloning
    • Produce enzymes like Taq DNA polymerase for PCR
    • Bioremediation: clearing pollutants
    • Produce vitamins, antibiotics, and hormones
    • Produce bio-plastics

    Archaea

    • Some live in extreme environments
    • Include extreme halophiles (salt-loving), extreme thermophiles (heat-loving), and methanogens (methane-producing organisms)

    Bacteria

    • Wide diversity, including: -Chlamydias (live within animal cells) -Spirochetes (spiral-shaped bacteria) -Cyanobacteria (photosynthetic bacteria) -Gram-positive bacteria (thick peptidoglycan layer) -Proteobacteria (diverse, includes aerobes and anaerobes)

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    Description

    Explore the fascinating world of prokaryotes, the first organisms on Earth. Learn about their unique characteristics, classification, and environments they thrive in, including extreme conditions. This quiz covers essential aspects of Monera and their diverse shapes and structures.

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