Podcast
Questions and Answers
The process of propagating organisms by providing proper environmental conditions is called ______.
The process of propagating organisms by providing proper environmental conditions is called ______.
cultivation
Microorganisms require metabolic energy to synthesize macromolecules and maintain essential chemical ______ across their membranes.
Microorganisms require metabolic energy to synthesize macromolecules and maintain essential chemical ______ across their membranes.
gradients
The three major mechanisms for generating metabolic energy are fermentation, respiration, and ______.
The three major mechanisms for generating metabolic energy are fermentation, respiration, and ______.
photosynthesis
To isolate a particular type of organism from a natural source, a single cell must be ______ from all other cells.
To isolate a particular type of organism from a natural source, a single cell must be ______ from all other cells.
The ideal gelling agent for most microbial media is ______, an acidic polysaccharide extracted from certain red algae.
The ideal gelling agent for most microbial media is ______, an acidic polysaccharide extracted from certain red algae.
The survival of any microbial group is determined by maintenance of a pool of living nutritional ______
The survival of any microbial group is determined by maintenance of a pool of living nutritional ______
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.
Growth involves the duplication of cells, resulting in an increase in the number of individuals in the ______
Growth involves the duplication of cells, resulting in an increase in the number of individuals in the ______
The bacterial growth curve represents the population dynamics of bacteria growing in a closed ______
The bacterial growth curve represents the population dynamics of bacteria growing in a closed ______
One of the fundamental goals in microbiological cultivation is to determine the ______ & type of organism present in a given material.
One of the fundamental goals in microbiological cultivation is to determine the ______ & type of organism present in a given material.
The population of microorganisms in the biosphere is roughly constant; growth is counterbalanced by ______.
The population of microorganisms in the biosphere is roughly constant; growth is counterbalanced by ______.
During the lag phase, bacteria adapt to the new environment and prepare for active ______
During the lag phase, bacteria adapt to the new environment and prepare for active ______
In the exponential phase, cells divide at a constant rate, resulting in ______ population growth.
In the exponential phase, cells divide at a constant rate, resulting in ______ population growth.
The maximum stationary phase occurs when growth rate slows due to nutrient ______ and waste accumulation.
The maximum stationary phase occurs when growth rate slows due to nutrient ______ and waste accumulation.
In the decline or death phase, cells die at an ______ rate.
In the decline or death phase, cells die at an ______ rate.
Cells can be maintained in exponential phase by transferring them repeatedly into fresh medium of identical ______.
Cells can be maintained in exponential phase by transferring them repeatedly into fresh medium of identical ______.
Flashcards
Cultivation of microorganisms
Cultivation of microorganisms
The process of propagating organisms in controlled conditions for growth.
Metabolic energy mechanisms
Metabolic energy mechanisms
Three primary ways organisms generate energy: fermentation, respiration, photosynthesis.
Nutritional demands
Nutritional demands
Nutrients required by microorganisms to grow and thrive.
Isolation in pure culture
Isolation in pure culture
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Plating method
Plating method
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Dilution method
Dilution method
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Environmental factors for growth
Environmental factors for growth
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Biosphere microbial balance
Biosphere microbial balance
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Microbial survival
Microbial survival
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Growth definition
Growth definition
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Unicellular growth
Unicellular growth
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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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Study Notes
Cultivation of Microorganisms
- Cultivation is the process of growing organisms by providing suitable conditions
- Organisms need metabolic energy to create macromolecules and maintain chemical gradients across their membranes
- Nutrients must be accessible
- Microorganisms have diverse nutritional needs and energy sources
- Factors like nutrients, pH, temperature, aeration, salt concentration, and ionic strength of the medium must be controlled
- Cultivation methods involve choosing a suitable medium and isolating the bacteria in a pure culture
- Fundamental goals in microbiological cultivation include raising a crop of specific cells, determining the number and type of organisms in a sample, isolating a specific organism from a natural source.
Isolation of Microorganisms in Pure Culture
- A single cell must be isolated and grown separately to ensure a pure culture
- Several methods are available
- Plating method involves placing a small number of cells on a gelled medium (like agar) so each cell grows into its own colony
- Dilution method involves reducing the density of microorganisms in a sample through serial dilution and plating samples of each dilution
Survival of Microorganisms
- The population of microorganisms in the biosphere remains relatively constant because growth is countered by death
- Survival depends on maintaining a pool of living organisms, access to nutrients, and success in competition for resources.
The Meaning of Growth
- Growth involves a regular increase in the sum of all components of an organism
- In unicellular organisms like bacteria, growth involves cell duplication, increasing the number of individuals
The Growth Curve
- The bacterial growth curve shows the population dynamics of bacteria in a closed system (batch culture)
- It shows how the number of living cells changes over time with constant nutrients and environmental conditions
- The curve has distinct phases:
- Lag phase: Bacteria adapt, metabolic activity increases, but little to no cell division
- Exponential (log) phase: Cells divide at a constant rate
- Stationary phase: Growth rate slows; new cells equal dying cells; stable population size
- Death phase: Nutrients exhausted, toxic waste accumulates; cells die at an exponential rate
Phases of Bacterial Growth
- Lag phase: Bacteria adapt to the new environment, activity increases, but little cell division
- Exponential phase: Cells divide at a constant rate; maximum metabolic activity
- Stationary phase: Growth rate slows, new cells equal dying cells, population size stabilizes
- Death phase: Nutrients are depleted, waste accumulates, cells die exponentially
- Maintaining exponential phase: Cells can be maintained in exponential growth by transferring to fresh identical medium
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