57 Questions
Which element makes up the largest percentage of the dry weight of a bacterial cell?
Carbon
What is the most abundant macromolecule in a cell?
Proteins
Which element is required for the activity of several enzymes?
Potassium
Which element is commonly supplied to cells as sulfate?
Sulfur
Which element is present in the amino acids cysteine and methionine?
Sulfur
Which element is required to stabilize ribosomes, membranes, and nucleic acids?
Magnesium
Which element is an essential nutrient for marine microorganisms?
Sodium
Which elements are considered essential for living systems?
Hydrogen, oxygen, carbon, nitrogen, phosphorus, sulfur, and selenium
What is the primary composition of a microbial cell?
Proteins, nucleic acids, lipids, and polysaccharides
What percentage of a microbial cell's dry weight is made up of proteins?
55%
What are macronutrients?
Nutrients required in large amounts
What are micronutrients?
Nutrients required in trace amounts
How much does a single cell of Escherichia coli weigh approximately?
10-12g
How many elements are essential for microbial nutrition?
At least 7
Which metal plays a major role in cellular respiration?
Iron (Fe)
What are trace elements also known as?
Micronutrients
What are growth factors?
Organic micronutrients
Which type of culture media is prepared by adding precise amounts of pure chemicals to distilled water?
Defined media
What is the major importance of the carbon source in culture media?
It makes new cell material
What is the disadvantage of using complex media for culture?
Its nutritional composition is not known precisely
What is the purpose of a selective medium in microbiology?
To inhibit the growth of some microorganisms but not others
Which type of medium is less demanding to prepare for the growth of L. mesenteroides?
Complex medium
Which medium listed in Table 3.2 would not support the growth of any of the organisms other than T. thioparus?
Fourth medium
Which organism has the greatest biosynthetic capacity among the organisms listed in Table 3.2?
Thiobacillus thioparus
How is sterilization of culture media typically achieved?
Heating in an autoclave
What is aseptic technique used for in the microbiology laboratory?
To prevent contamination during manipulations
What is the main method for obtaining pure cultures from liquid samples containing different organisms?
Restreaking isolated colonies
What percentage of a microbial cell's dry weight is made up of proteins?
55%
Which elements are considered essential for living systems?
Hydrogen, oxygen, carbon, nitrogen, phosphorus, sulfur
What is the major importance of the carbon source in culture media?
It provides energy for microbial growth
What is aseptic technique used for in the microbiology laboratory?
To prevent contamination of microbial cultures
Which element is required for the activity of several enzymes?
Phosphorus
What is the purpose of a selective medium in microbiology?
To inhibit the growth of specific microorganisms
What are growth factors?
Specific organic compounds required in small amounts for microbial growth
Which element is required for the activity of several enzymes?
Potassium
What is the purpose of a selective medium in microbiology?
To inhibit the growth of unwanted microorganisms
What are growth factors?
Chemical compounds required for the growth of microorganisms
What is the major importance of the carbon source in culture media?
To provide energy for microbial growth
What is the most abundant macromolecule in a cell?
Proteins
What is aseptic technique used for in the microbiology laboratory?
To prevent contamination of microbial cultures
What are micronutrients?
Nutrients required in trace amounts by microorganisms
Which type of culture media is considered 'simple' because it contains only a single carbon source?
Defined media
Which type of media is made from digests of microbial, animal, or plant products and its nutritional composition is not known precisely?
Complex media
Which type of media is used for the culture of nutritionally demanding microorganisms and is embellished with additional highly nutritious substances?
Enriched media
Which type of media contains compounds that inhibit the growth of some microorganisms but not others?
Selective media
Which type of media reveals by a color change whether a particular metabolic reaction has occurred during growth?
Differential media
What is the primary purpose of aseptic technique in the microbiology laboratory?
To prevent contamination of cultures
How many essential elements are there for microbial nutrition?
7
What is the purpose of agar in solid culture media?
To immobilize cells and allow them to grow and form colonies
What is the main method for obtaining pure cultures from liquid samples containing several different organisms?
Picking an isolated colony and restreaking it
What is the purpose of aseptic technique in the microbiology laboratory?
To prevent contamination during manipulations of cultures and sterile culture media
Which element is required for the activity of several enzymes?
Sulfur
What is the major importance of the carbon source in culture media?
To provide energy and serve as a building block for cellular components
Which element is present in the amino acids cysteine and methionine?
Sulfur
What is the disadvantage of using complex media for culture?
It requires the addition of several individual nutrients
Which type of medium is less demanding to prepare for the growth of L. mesenteroides?
Complex medium
Which organism has the greatest biosynthetic capacity among the organisms listed in Table 3.2?
T. thioparus
Test your knowledge of essential metals and trace elements in cellular metabolism with this quiz. Explore the role of iron and other micronutrients in electron transport reactions and learn about their importance to microorganisms.
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