Podcast
Questions and Answers
The process of propagating organisms by providing the proper environmental conditions is known as ______.
The process of propagating organisms by providing the proper environmental conditions is known as ______.
cultivation
Microorganisms need ______ to synthesize macromolecules and maintain essential chemical gradients.
Microorganisms need ______ to synthesize macromolecules and maintain essential chemical gradients.
metabolic energy
When cultivating microorganisms, factors like nutrients, pH, temperature, and ______ must be controlled.
When cultivating microorganisms, factors like nutrients, pH, temperature, and ______ must be controlled.
aeration
Fermentation, respiration, and photosynthesis are the three major mechanisms for generating ______.
Fermentation, respiration, and photosynthesis are the three major mechanisms for generating ______.
The plating method involves placing a limited number of cells in or on a ______ medium.
The plating method involves placing a limited number of cells in or on a ______ medium.
Agar, a polysaccharide extracted from red algae, is an ideal ______ agent for most microbial media.
Agar, a polysaccharide extracted from red algae, is an ideal ______ agent for most microbial media.
The dilution method reduces the density of microorganisms in a sample through ______ dilution.
The dilution method reduces the density of microorganisms in a sample through ______ dilution.
In the natural environment, the population of microorganisms is roughly ______.
In the natural environment, the population of microorganisms is roughly ______.
The survival of any microbial group within its environment is determined by the maintenance of a pool of living ______ and by successful competition for nutrients.
The survival of any microbial group within its environment is determined by the maintenance of a pool of living ______ and by successful competition for nutrients.
Growth is the regular increase in the sum of all components of an ______.
Growth is the regular increase in the sum of all components of an ______.
In unicellular microorganisms, such as bacteria, growth involves the ______ of cells.
In unicellular microorganisms, such as bacteria, growth involves the ______ of cells.
The bacterial growth curve represents the population dynamics of bacteria growing in a closed system, also known as a ______ culture.
The bacterial growth curve represents the population dynamics of bacteria growing in a closed system, also known as a ______ culture.
The ______ phase is when bacteria adapt to their environment and prepare for active division.
The ______ phase is when bacteria adapt to their environment and prepare for active division.
During the ______ phase, cells divide at a constant rate, resulting in exponential population growth.
During the ______ phase, cells divide at a constant rate, resulting in exponential population growth.
The maximum stationary phase occurs when growth rate slows due to nutrient depletion and ______ accumulation.
The maximum stationary phase occurs when growth rate slows due to nutrient depletion and ______ accumulation.
During the decline or death phase, nutrients are exhausted, and toxic waste products accumulate leading to a decline in the number of living ______.
During the decline or death phase, nutrients are exhausted, and toxic waste products accumulate leading to a decline in the number of living ______.
Flashcards
Microbial survival
Microbial survival
Microbial survival relies on nutrient competition and deprivation management.
Growth in organisms
Growth in organisms
Growth is the regular increase in mass or size of all components of an organism.
Unicellular growth
Unicellular growth
In unicellular organisms, growth means cell duplication, increasing population size.
Bacterial growth curve
Bacterial growth curve
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Lag phase
Lag phase
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Exponential phase
Exponential phase
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Maximum stationary phase
Maximum stationary phase
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Decline phase
Decline phase
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Cultivation of microorganisms
Cultivation of microorganisms
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Metabolic energy mechanisms
Metabolic energy mechanisms
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Nutritional demands
Nutritional demands
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Isolation of microorganisms
Isolation of microorganisms
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Plating method
Plating method
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Dilution method
Dilution method
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Factors for growth control
Factors for growth control
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Microbial survival in nature
Microbial survival in nature
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Study Notes
Cultivation of Microorganisms
- Cultivation is the process of growing microorganisms by providing suitable environmental conditions.
- Microorganisms need metabolic energy to synthesize macromolecules and maintain chemical gradients.
- Nutrients must be in a usable form.
- Factors like nutrients, pH, temperature, aeration, salt concentration, and ionic strength influence growth.
- Three major metabolic energy mechanisms are fermentation, respiration, and photosynthesis.
Cultivation Methods
- Two key aspects for cultivation are the choice of a suitable medium and isolation of bacteria in pure culture.
- Fundamental goals in microbiological cultivation include:
- Obtaining a crop of specific cells.
- Determining the number and type of organisms in a sample.
- Isolating a specific organism from a source.
- Isolation in pure culture involves isolating a single cell from other cells to maintain isolated progeny.
Plating Method
- If a small number of cells are placed on a gel medium, each cell will grow into a discrete colony.
- Agar, an acidic polysaccharide from red algae, is a good gelling agent for microbal media.
Dilution Method
- Reduces the density of microorganisms in a sample through serial dilution.
- Diluted sample is plated or inoculated to isolate single cells.
- Single cells grow into pure colonies.
- Samples from each dilution are plated or streaked on solid media.
Survival of Microorganisms in the Natural Environment
- The population of microorganisms in the biosphere is roughly constant; growth is counterbalanced by death.
- Survival depends on maintaining a pool of living organisms and successful nutrient competition.
Meaning of Microorganism Growth
- Growth means a regular increase in the organism's components (size or mass).
- In unicellular organisms, growth results in an increase in the number of individuals.
Bacterial Growth Curve
- The bacterial growth curve showcases the population dynamics in a closed system (batch culture).
- The curve shows the changes in the number of living cells over time.
- The curve has distinct phases: lag, exponential, stationary, and death.
The Lag Phase
- Bacteria adapt to the new environment.
- Increased metabolic activity, but little to no cell division.
- Duration depends on the organism and environmental conditions.
- Key processes include synthesis of enzymes, proteins, and other molecules for growth.
The Exponential Phase
- Cells divide at a constant rate, leading to exponential population growth.
- Each generation, the population roughly doubles.
- Bacteria are highly metabolically active and sensitive to antibiotics.
- Key processes include DNA replication, protein synthesis, and active metabolism.
The Stationary Phase
- Growth rate slows due to nutrient depletion and waste accumulation.
- Number of new cells equals the number of dying cells.
- Population size stabilizes.
- Key processes include adjusting metabolism to stress conditions and secondary metabolite production.
The Death Phase
- Nutrients are exhausted and toxic waste accumulates.
- Cells die at an exponential rate.
- Some bacteria form spores or enter a dormant state.
- Key processes include lysis and breakdown of cellular structures in dead cells.
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