Questions and Answers
What is the lag phase of bacteria growth?
Lack of growth; bacteria increase in size and become fat due to accumulation of ATP and adaptation to the environment.
What characterizes the log phase of bacteria growth?
Exponential growth; the number of live cells produced is greater than the number of dead cells in a 1000 to 1 ratio.
What occurs during the stationary phase of bacteria growth?
The number of live cells is equal to the number of dead cells produced.
What happens in the decline phase of bacteria growth?
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Which of the following are physical factors that affect bacterial growth? (Select all that apply)
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Which of the following are biochemical/nutritional factors that affect bacterial growth? (Select all that apply)
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Study Notes
Phases of Bacteria Growth
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Lag phase:
- Characterized by no significant growth; cells increase in size due to ATP accumulation.
- Bacteria adapt to their environment during this phase.
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Log phase:
- Exhibits exponential growth; live cells outnumber dead cells by a ratio of 1000:1.
- Growth ceases when resources (space, food, oxygen) are depleted and pH drops below 5.
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Stationary phase:
- The number of live cells stabilizes, equal to the number of dead cells.
- This phase represents a balance in population dynamics.
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Decline phase:
- Characterized by a lack of food and oxygen; dead cells outnumber live cells at a ratio of 1000:1.
- Involution occurs, indicating deterioration and decline in cell health.
Factors Affecting Bacteria Growth
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Physical factors:
- pH levels: Optimal pH is crucial for growth.
- Temperature: Each bacteria species thrives at specific temperature ranges.
- Oxygen levels: Oxygen concentration significantly influences growth rates.
- Sodium chloride concentration: Affects osmotic pressure and survivability.
- Radiation: Can have lethal or mutagenic effects on bacterial cells.
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Biochemical / nutritional factors:
- Nitrogen: Essential for amino acid and protein synthesis.
- Carbon: Primary source of energy and building block for bacterial cells.
- Phosphorus: Vital for energy transfer (ATP) and nucleic acid formation.
- Micronutrients: Trace elements necessary for various enzymatic reactions and cellular functions.
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Description
Explore the different phases of bacterial growth, including lag, log, stationary, and decline phases. Understand the physical factors such as pH, temperature, and oxygen levels that significantly impact the growth of bacteria.
