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Questions and Answers

Which characteristic does NOT define a microbe?

  • Being microscopic
  • Being unicellular
  • Being able to be seen with the naked eye (correct)
  • Being able to reproduce

What distinguishes fungi from many other types of microbes?

  • Fungi are primarily aquatic organisms.
  • Fungi are always unicellular.
  • Fungi can be macroscopic and multicellular. (correct)
  • Fungi cannot reproduce.

Which of the following statements is true regarding the sizes of microbes?

  • All microbes can be seen without a microscope.
  • Some fungi are macroscopic and may be multicellular. (correct)
  • All bacteria are microscopic and unicellular.
  • All algae are multicellular organisms.

What organism classification system did Carl Woese and his colleagues propose?

<p>Three-domain system (B)</p> Signup and view all the answers

Why is it incorrect to categorize all microbes as unicellular?

<p>Many fungi and algal forms are multicellular. (A)</p> Signup and view all the answers

What misconception about microbes may arise when considering their visibility?

<p>All microbes can be observed without special tools. (C)</p> Signup and view all the answers

Which of the following organisms belongs to the domain Eucarya?

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

What technique did Woese use to identify the relatedness of microbes?

<p>Ribosomal nucleic acid analysis (B)</p> Signup and view all the answers

How can molds be classified based on their visibility?

<p>Molds are macroscopic and can be seen with the naked eye. (D)</p> Signup and view all the answers

Which statement about the characteristics of microbes is accurate?

<p>Some microbes, like yeasts, are unicellular. (D)</p> Signup and view all the answers

Which two groups of organisms are considered prokaryotic in the Woese classification system?

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

What historical concept does the Woese classification system challenge?

<p>Distinct separation of organisms into eukaryotes and prokaryotes (B)</p> Signup and view all the answers

Which of the following is NOT a common misconception about microbes?

<p>Microbes can include macroscopic organisms. (A)</p> Signup and view all the answers

Which of the following is NOT a domain in the Woese classification system?

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

What type of organisms does the domain Archaea primarily consist of?

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

What did Woese's analysis of ribosomal nucleic acid help to determine?

<p>The evolutionary history and relatedness of organisms (C)</p> Signup and view all the answers

What unique ability does Deinococcus radiodurans possess that allows it to withstand high levels of gamma radiation?

<p>It can repair its damaged DNA. (B)</p> Signup and view all the answers

How many new organisms were discovered in the human mouth by scientists at Stanford University?

<p>Thirty-seven (C)</p> Signup and view all the answers

Why had the new microbes in the human mouth remained unknown prior to recent studies?

<p>Traditional culture methods did not allow their growth. (D)</p> Signup and view all the answers

What do the National Science Foundation and the American Society for Microbiology aim to achieve with their global microbial survey?

<p>To identify and catalog microbes that make up the biosphere. (D)</p> Signup and view all the answers

What is the estimated percentage of microbial population that has been identified so far?

<p>Less than 2% (C)</p> Signup and view all the answers

What intriguing question about Earth's origins remains speculative?

<p>The origins of life on Earth. (A)</p> Signup and view all the answers

What term is used to describe microbiologists who extract DNA from dental plaque?

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

What is the estimated diversity of ecosystems in the human mouth compared to other environments?

<p>Rivals the biodiversity of tropical rainforests. (D)</p> Signup and view all the answers

What is the defining characteristic of prions that distinguishes them from viruses?

<p>Prions lack nucleic acids entirely. (D)</p> Signup and view all the answers

What disease is NOT caused by prions?

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

What is the significance of the 1997 Nobel Prize awarded to Stanley Prusiner?

<p>It legitimized prions as separate entities. (D)</p> Signup and view all the answers

How are viruses characterized in relation to their replication?

<p>They are obligate intra-cellular parasites. (D)</p> Signup and view all the answers

Which of the following statements about viruses is incorrect?

<p>Viruses can be observed with a light microscope. (D)</p> Signup and view all the answers

What do prions primarily convert in the body?

<p>Normal proteins into disease-causing proteins. (B)</p> Signup and view all the answers

Which of the following is NOT a characteristic of viruses?

<p>They contain both RNA and DNA. (D)</p> Signup and view all the answers

Where do prions primarily exist in the body?

<p>In the brain. (D)</p> Signup and view all the answers

What is a major distinguishing feature between procaryotic and eucaryotic cells?

<p>Presence of a nuclear membrane (D)</p> Signup and view all the answers

Most bacteria are typically classified as which of the following?

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

Which unit of measurement is the smallest?

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

Which of the following are classified as obligate intracellular parasites?

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

Which of the following does not contain nucleic acid in its structure?

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

The five-kingdom system of taxonomy is attributed to which scientist?

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

According to Woese, how did Eucarya arise?

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

Which organisms do not require organic compounds for growth?

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

What defines viruses and prions in terms of biological classification?

<p>They are not classified as procaryotic or eucaryotic. (D)</p> Signup and view all the answers

Which of the following statements about microbial classification is accurate?

<p>Woese's classification system is based on rRNA analysis. (B)</p> Signup and view all the answers

How do microbes adapt to extreme ecological conditions?

<p>By developing diverse metabolic strategies. (A)</p> Signup and view all the answers

What distinguishes procaryotic bacteria from other microbes?

<p>They are unicellular and lack membrane-bound organelles. (C)</p> Signup and view all the answers

What is one misconception regarding the terms 'bugs' and 'germs'?

<p>They are collective terms for diverse microbial agents. (A)</p> Signup and view all the answers

What major characteristic do all organisms, including microbes, need to fulfill?

<p>The requirement for energy. (A)</p> Signup and view all the answers

What is the historical trend in the classification of microbes?

<p>Recognizing the uniqueness of different microbial groups. (C)</p> Signup and view all the answers

Which of the following best describes the origin of microbes on Earth?

<p>They emerged in extreme environments and spread out. (D)</p> Signup and view all the answers

Flashcards

Microbial size

Microscopic size is not a defining characteristic of all microbes.

Microbial Unicellularity

Not all microbes are single-celled; some are multicellular.

Defining Microbes

The defining characteristics of microbes are complex and not easily summarized.

Macroscopic Microbes

Some microbes, like certain fungi, can be seen without a microscope.

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Microscopic Microbes

Some microbes, like bacteria, are too small to be seen without a microscope.

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Woese's three domains

Bacteria, Archaea, and Eucarya, are the three major divisions of life according to Woese's system. They originated from a common ancestor.

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Carl Woese

A biologist who developed a new classification system based on ribosomal nucleic acid (rRNA).

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Universal Ancestor

A single ancestral cell from which all life forms on Earth originated.

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rRNA

Ribosomal RNA; used to identify shared characteristics of microorganisms for studying their evolutionary history.

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Bacteria

One of the three domains of life; prokaryotic organisms.

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Archaea

One of the three domains of life; prokaryotic organisms that differ from Bacteria

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Eucarya

One of the three domains of life encompassing all eukaryotic organisms (those with membrane-bound organelles).

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Prokaryotic

Describes organisms that lack a cell nucleus and other membrane-bound organelles.

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Eubacteria

An older name for the Bacteria domain.

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Archaebacteria

An older name for the Archaea domain.

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Prions

Protein molecules that are infectious and lack DNA or RNA.

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Prion disease

Diseases caused by abnormal prions which convert normal proteins into infectious versions.

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Viruses

Submicroscopic particles that contain DNA or RNA, not both.

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Obligate intracellular parasite

A microbe that needs a host cell to multiply and reproduce. Viruses are an example.

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Submicroscopic particles

Objects or particles that are too small to be seen with the naked eye, electron microscope required

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Viruses: DNA/RNA

Viruses contain either DNA or RNA, but never both.

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Deinococcus radiodurans

A bacterium highly resistant to radiation, able to withstand significantly more gamma radiation than humans.

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Human mouth ecosystem

A highly diverse ecosystem, rivaling tropical rainforests in biological complexity.

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New mouth microbes

Recently discovered microorganisms living in plaque between teeth, previously unknown due to limitations in traditional culture methods.

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DNA sequencing

A method to map out DNA sequences for organisms, crucial for identifying previously unknown microbes.

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Microbial population identification

A significant portion of microbes remain unknown, much less than 2% currently identified.

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Global microbial survey

An ongoing effort to identify and catalog microbes in the biosphere, coordinated by organizations like NSF and ASM.

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Microbial biodiversity research

Scientists and organizations are establishing sites, or observatories, dedicated to studying microbial biodiversity worldwide.

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Origin of life

The question of how life began on Earth, currently debated and considered speculative.

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Viruses and prions

Subcellular entities not considered living organisms.

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Microbial organization

Microbial structures are all below the tissue level of biological organization.

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Bacteria

Prokaryotic microbes, with a simple cell structure.

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Other microbes

Eukaryotic microbes, with complex cell structures.

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Taxonomy (Microbes)

System of classifying microbes, evolving from simpler to more complex systems.

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Woese's classification

Microbes classified into three domains based on rRNA analysis, reflecting evolutionary history.

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Microbial Environments

Microbial life can be found in a diverse range of environments, including extreme ones.

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Energy for microbes

Microbes have a range of strategies for obtaining energy, including organic compounds, sunlight, and inorganic compounds.

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Microbial diversity

Microbial groups are distinct and diverse, with many ways to acquire energy

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"Bugs" and "germs"

Common, but inaccurate, terms for a variety of distinct microbial agents.

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Procaryotic vs. Eucaryotic Cells

The major difference between procaryotic and eucaryotic cells is the presence of a nuclear membrane. Procaryotic cells lack a nucleus and a nuclear membrane, while eucaryotic cells have both.

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Most Bacteria

Most bacteria are categorized as heterotrophs, meaning they obtain energy by consuming organic compounds.

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Smallest Unit of Measurement

The nanometer is the smallest unit of measurement among the options provided.

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Obligate Intracellular Parasites

Viruses are obligate intracellular parasites; they require a living host cell to reproduce.

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Structure Lacking Nucleic Acid

Prions are infectious agents that lack nucleic acid (DNA or RNA) in their structure.

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Five-Kingdom System

The five-kingdom system of taxonomy was developed by Robert Whittaker.

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Woese's Taxonomy

Woese proposed that Bacteria, Archaea, and Eucarya arose separately.

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Microbes

Microbes include bacteria, viruses, fungi, and protozoans.

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Cell Theory

The cell theory describes the fundamental concept that all living things are composed of cells.

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Organic Compounds

Compounds containing carbon are called organic compounds.

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Organisms without Organic Input

Organisms that do not require organic compounds are called autotrophs.

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Energy Compound

Adenosine triphosphate (ATP) is often referred to as the energy compound.

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Study Notes

The Microbial World

  • Microbes are incredibly small, often invisible without a microscope
  • Many microbes are not harmful pathogens
  • Microbes are classified into six groups: bacteria, viruses, protozoans, unicellular algae, fungi, and prions
  • Cells are the basic unit of life.
  • All organisms are either unicellular or multicellular
  • All cells are fundamentally alike in reference to structure and metabolism
  • Cells arise only from previously existing cells

Microbial Principles

  • Cell theory postulates that: All organisms are composed of cells; all cells come from pre-existing cells and all cells are fundamentally alike in structure and metabolism
  • Metabolic diversity is a key characteristic of living systems
  • Organisms need energy to survive.
  • Autotrophs make their own food
  • Heterotrophs derive energy from consuming other organisms
  • Organisms require oxygen in varying levels to survive, categorized as aerobes (require oxygen), anaerobes (do not require oxygen), and facultative anaerobes (better in oxygen environments, but can survive without it)

Microbes

  • Microbes are defined as biological agents that are generally too small to be seen without a microscope
  • Microbes are either prokaryotic or eukaryotic
  • Prokaryotes lack a membrane-bound nucleus and other organelles
  • Eukaryotes have a membrane-bound nucleus and other membrane-bound organelles
  • Classification of microbes has evolved over time
  • The modern approach to classification is based on the three-domain system (Bacteria, Archaea, and Eukarya)
  • Microbes, despite their small size, play essential environmental functions

Procaryotic and Eucaryotic Cell

  • Prokaryotic cells are simpler in structure than eukaryotic cells, with no membrane-bound nucleus, and no organelles
  • Eukaryotic cells are more complex with a membrane-bound nucleus and many membrane-bound organelles in the cytoplasm
  • The primary difference is presence of a membrane-bound nucleus or nucleoid.

Microbial Evolution and Diversity

  • Procaryotes (bacteria and archaea) are older than eucaryotes
  • Microbes have existed for billions of years on Earth
  • Microbes have adapted to a wide range of environments
  • Microbes play important roles in various ecosystems, including as decomposers, producers, and symbionts with other organisms

Prions and Viruses

  • Prions are protein molecules lacking nucleic acid, and cause infectious disease in mammals
  • Viruses are non-cellular agents consisting of genetic material (either DNA or RNA) surrounded by a protein coat and are dependent on a host cell to replicate
  • Viruses are not considered complete living things because they cannot reproduce without a host cell.

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