U1.C3.1 Laboratory culture of microorganisms
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Questions and Answers

Which element is required for the activity of several enzymes?

  • Magnesium
  • Phosphorus
  • Potassium (correct)
  • Sulfur

    • What are growth factors?

  • Organic micronutrients required for growth (correct)
  • Trace elements that function as cofactors for enzymes
  • Inorganic compounds needed for cell growth
  • Compounds used as carbon sources

    • Which type of media is considered 'simple' because it contains only a single carbon source?

  • Complex media
  • Selective media
  • Differential media
  • Defined media (correct)

    • What is the disadvantage of using a complex medium for culturing microorganisms?

    <p>Its nutritional composition is not known precisely</p> Signup and view all the answers

    What is the purpose of a selective medium in diagnostic microbiology?

    <p>To inhibit the growth of certain microorganisms</p> Signup and view all the answers

    Which organism listed in Table 3.2 has the greatest biosynthetic capacity?

    <p>Thiobacillus thioparus</p> Signup and view all the answers

    Which elements are considered essential for microbial life?

    <p>Hydrogen, oxygen, carbon, nitrogen, phosphorus, sulfur, and selenium</p> Signup and view all the answers

    What is the chemical makeup of a microbial cell primarily composed of?

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

    What is the percentage of proteins in the total cell dry weight?

    <p>55%</p> Signup and view all the answers

    Which element is required for the activity of several enzymes?

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

    What is the main role of iron in cellular respiration?

    <p>To stabilize ribosomes, membranes, and nucleic acids</p> Signup and view all the answers

    What is the disadvantage of using a complex medium for culturing microorganisms?

    <p>It promotes the growth of unwanted contaminants</p> Signup and view all the answers

    What is a common indication of a contaminated culture?

    <p>Presence of foul odor</p> Signup and view all the answers

    What is the purpose of agar in solid culture media?

    <p>To immobilize cells and allow them to grow</p> Signup and view all the answers

    Which organism listed in Table 3.2 has the most demanding nutritional requirements?

    <p>T. thioparus</p> Signup and view all the answers

    What is the purpose of aseptic technique in microbiology?

    <p>To prevent contamination during manipulations</p> Signup and view all the answers

    What is the main method for obtaining pure cultures from liquid samples containing several different organisms?

    <p>Restreaking an isolated colony</p> Signup and view all the answers

    Which of the following is NOT a type of culture medium used in microbiology?

    <p>Selective media</p> Signup and view all the answers

    Which of the following is true about growth factors?

    <p>They are organic micronutrients</p> Signup and view all the answers

    Which of the following is an advantage of using a complex medium?

    <p>It supports growth of fastidious microorganisms</p> Signup and view all the answers

    Which of the following is a characteristic of selective media?

    <p>They contain compounds that inhibit the growth of all microorganisms</p> Signup and view all the answers

    Study Notes

    Enzymes and Essential Elements

    • Iron is required for the activity of several enzymes.
    • Iron plays a crucial role in cellular respiration.

    Microbial Growth and Media

    • Simple media contain a single carbon source.
    • Complex media have a disadvantage, as they can support the growth of contaminants, making it difficult to isolate the desired microorganism.
    • Selective media are used in diagnostic microbiology to isolate specific microorganisms.
    • Agar is used in solid culture media to provide a solid surface for microorganisms to grow.

    Microbial Composition

    • Microbial cells are primarily composed of carbon, oxygen, nitrogen, and hydrogen.
    • Proteins make up approximately 50% of the total cell dry weight.

    Microorganisms and Nutritional Requirements

    • The organism with the greatest biosynthetic capacity is Escherichia coli (E. coli).
    • The organism with the most demanding nutritional requirements is Lactobacillus acidophilus.

    Aseptic Technique and Culture Methods

    • Aseptic technique is used in microbiology to prevent contamination of cultures.
    • The main method for obtaining pure cultures from liquid samples containing several different organisms is through the use of selective media and aseptic technique.

    Culture Media and Characteristics

    • Defined media, complex media, and selective media are types of culture media used in microbiology.
    • Growth factors are organic compounds required by some microorganisms for growth.
    • A characteristic of selective media is that they allow only specific microorganisms to grow.

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    Test your knowledge on culture media and carbon sources used for culturing microorganisms. Learn about different recipes for culture media and understand the role of carbon sources in microbial growth.

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