Biology: Prokaryotes, Eukaryotes, and the Three Domains
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Questions and Answers

What is the basis of genotypic classification of bacteria?

  • Cultural characteristics and environmental factors
  • DNA-DNA hybridization and G+C content (correct)
  • Antigenic structure and nutrition
  • Morphological characteristics

    • What is the main purpose of 16S rRNA sequences in classifying prokaryotes?

  • To identify the shape of the bacterium
  • To analyze the nucleotide sequence differences (correct)
  • To detect the presence of peptidoglycan in the cell wall
  • To determine the G+C content of the DNA

    • Which of the following is a characteristic of Gram-positive bacteria?

  • They have a thick peptidoglycan layer (correct)
  • They are halophiles
  • They lack a cell wall
  • They have a thin peptidoglycan layer

    • What is the primary function of genetic probes in DNA analysis?

    <p>To identify specific DNA sequences</p> Signup and view all the answers

    Which group of bacteria includes methanogens and extreme thermophiles?

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

    What is the primary basis of phenotypic classification of bacteria?

    <p>All of the above</p> Signup and view all the answers

    What is the main advantage of using rRNA sequence analysis in classifying prokaryotes?

    <p>It provides evolutionary context and makes biological sense</p> Signup and view all the answers

    What is the primary characteristic of halophiles?

    <p>They thrive in high-salt environments</p> Signup and view all the answers

    What is a characteristic of Archaea that distinguishes them from bacteria?

    <p>Having unique genetic sequences in their rRNA</p> Signup and view all the answers

    Which of the following is NOT a characteristic of Eukaryotes?

    <p>Lacking membrane lipids</p> Signup and view all the answers

    What is the name of the kingdom that includes protozoa in the Whittaker classification?

    <p>Kingdom Protista</p> Signup and view all the answers

    What is a characteristic of protozoa?

    <p>Lacking photosynthetic capability</p> Signup and view all the answers

    Which of the following is an example of an extreme environment that Archaea can thrive in?

    <p>High-temperature hot springs</p> Signup and view all the answers

    What is the term for organisms that are adapted to live in extreme environments?

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

    What is the key characteristic of heterotrophic organisms like fungi?

    <p>Cannot produce their own food</p> Signup and view all the answers

    What is the primary source of energy and carbon for fungi?

    <p>Organic compounds</p> Signup and view all the answers

    What is the common characteristic of the cells of fungi?

    <p>Usually organized into branched, multinucleate filaments</p> Signup and view all the answers

    What is the term for the network of tubes that make up mushrooms?

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

    How many species of fungi are estimated to exist?

    <p>100,000</p> Signup and view all the answers

    What is the characteristic of yeast fungi?

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

    What is the primary basis for fungal classification?

    <p>Spore-forming structures and sexual spores</p> Signup and view all the answers

    What is the term for the filaments that make up mycelia?

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

    What is the primary method used to quantify viruses?

    <p>Counting the number of plaques</p> Signup and view all the answers

    What is the study of viruses called?

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

    What are the two main components of a virus?

    <p>Nucleic acid and capsid</p> Signup and view all the answers

    What is unique about retroviruses?

    <p>They have a single-stranded RNA genome</p> Signup and view all the answers

    What is the primary function of the capsid?

    <p>To protect the viral genome</p> Signup and view all the answers

    What is the classification of viruses based on?

    <p>Multiple parameters including the type of genomic nucleic acid, size of the virion and genome, and more</p> Signup and view all the answers

    What is a characteristic of viroids?

    <p>They are infectious pieces of naked RNA</p> Signup and view all the answers

    What is a characteristic of prions?

    <p>They are infectious proteins</p> Signup and view all the answers

    What is the name of the domain that includes humans, animals, and plants?

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

    What does the prefix 'pro' mean in the term 'prokaryotes'?

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

    What is the level of classification that is used to identify each creature in binomial nomenclature?

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

    What is the term for the naming system used to identify microorganisms?

    <p>Binomial Nomenclature</p> Signup and view all the answers

    What is the correct way to write the genus name in binomial nomenclature?

    <p>In uppercase letters</p> Signup and view all the answers

    What is the characteristic that distinguishes eukaryotes from prokaryotes?

    <p>Presence of a nucleus</p> Signup and view all the answers

    What is the order of classification in the taxonomic hierarchy?

    <p>Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species</p> Signup and view all the answers

    What is the abbreviation for the species Escherichia coli?

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

    Study Notes

    Cell Classification

    • Three domains: Bacteria, Archaea, and Eukarya
    • Bacteria: prokaryotes, lack peptidoglycan, binary fission, energy from organic chemicals, inorganic chemicals, or photosynthesis
    • Archaea: prokaryotes, lack peptidoglycan, live in extreme environments, include methanogens, extreme halophiles, and extreme thermophiles
    • Eukarya: eukaryotic cells, have a nucleus, organelles, reproduce asexually or sexually, examples include protozoans, molds, plants, and animals

    Taxonomic Hierarchy

    • Domain: highest level of classification
    • Kingdom: second level of classification
    • Phylum: third level of classification
    • Class: fourth level of classification
    • Order: fifth level of classification
    • Family: sixth level of classification
    • Genus: seventh level of classification
    • Species: eighth level of classification

    Binomial Nomenclature

    • Uses Genus and Species names to identify each creature
    • Examples: Escherichia coli, Staphylococcus aureus, Bacillus subtilis

    Microorganism Classification

    • Phenotypic classification: based on shape, size, and staining
    • Genotypic classification: based on DNA-DNA hybridization, G+C content, and rRNA sequence

    Bacteria Shapes

    • Three main shapes: Cocci, Bacilli, and Spiral

    Cell Wall Composition

    • Four groups: Gram-positive, Gram-negative, bacteria without cell walls, and bacteria with chemically unique cell walls

    rRNA Sequence

    • Used to classify prokaryotes
    • 16S rRNA sequences and 23S rRNA sequences are used

    Archaea

    • Prokaryotes, lack peptidoglycan, live in extreme environments
    • Include methanogens, extreme halophiles, and extreme thermophiles

    Eukaryotes

    • Eukaryotic cells, have a nucleus, organelles, reproduce asexually or sexually
    • Examples include protozoans, molds, plants, and animals

    Kingdom Protista

    • Microscopic unicellular organisms, lack photosynthetic capability, usually motile, reproduce by asexual fission
    • Examples include protozoans

    Kingdom Fungi

    • Heterotrophic, require organic compounds for energy and carbon source
    • Cells are usually organized into branched, multinucleate filaments which absorb digested food from the external environment
    • Examples include yeasts, molds, and mushrooms

    Fungal Characteristics

    • Chitin cell walls, use organic chemicals for energy, multicellular consisting of masses of mycelia, which are composed of filaments called hyphae
    • Yeasts are unicellular

    Viruses

    • Acellular, obligate intracellular parasites, no ribosomes or means of protein synthesis, no ATP generating system
    • Not alive
    • Classified based on type of genomic nucleic acid, size of virion and genome, capsid structure, host, and replication mechanism

    Virus Structure

    • Two parts: nucleic acid (either DNA or RNA) and capsid (protein coat)
    • Some capsids surrounded by envelopes

    Viroids and Prions

    • Viroids: infectious pieces of naked RNA, cause plant diseases, 300-400 nucleotides long, closed, folded 3D shape
    • Prions: infectious proteins, cause diseases such as Mad cow and Creutzfeldt-Jakob

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    Description

    Learn about the differences between prokaryotes and eukaryotes and explore the three domains of life: Bacteria, Archaea, and Eukarya.

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