Growth, Nutrition, and Ecology Flashcards
- Nutrients and Energy
- Physical (Environmental) Factors
- Oxygen
- Temperature
- pH
- Water
- Salt
Growth Requirements
How does bacteria divide?
Binary fusion
Binary Fusion
- Binary fusion is how bacteria divides
- Each parent cell leads to two daughter cells
–Time required for a bacterial cell to grow and divide
–Dependent on chemical and physical conditions
Generation Time (bacterial growth)
–Growth of bacterial populations
–Number of bacteria doubles each generation
–1 to 2 to 4 to 8 to 16, etc.
–20 to 21 to 22 to 23 to 24, etc.
–Exponent is generation number
–2n
Exponential Growth (bacteria)
•If you grow a bacterial culture that divides every 30 minutes for a total of 16 hours –
–How many generations have occurred?
–How many more cells will there be after 16 hours?
- Generations:
- 16 hrs x 2 generations = 32 generations
- Number of cells
- n = generation
- 232= 4294967296 bacteria cells
How do growth conditions affect generation time and growth?
Generatin time and growth are dependent on chemical and physical conditions
- Nutrients and Energy
- Physical (Environmental) Factors
- Oxygen
- Temperature
- pH
- Water
- Salt
- Pattern of population growth in laboratory samples
- Does not describe populations in nature
- Fundamental for laboratory work, as bacteria behave differently in each phase
Standard Growth Curve
Standard Growth Curve
- Pattern of population growth in laboratory samples
- Does not describe populations in nature
- Fundamental for laboratory work, as bacteria behave differently in each phase
–Little growth, no death
–Bacteria acclimating to new environment
–Cells increase in size, but do not divide
–No change in population size
Lag Phase of Standard Growth Curve
–most rapid growth
–exponential increase in population size
–nutrients plentiful, very few waste products in culture
–growth rate >> death rate
–for many experiments, this is ideal time for study
Log Phase of Standard Growth Curve
–No change in population size
–growth rate = death rate
–Nutrients are decreasing
–Waste products are increasing
–Sporulation begins here
Stationary Phase of Standard Growth Curve
–Numbers of live bacteria in population declines
–Death rate > growth rate
–Nutrients depleted
–Waste products abundant
Death/Decline Phase of Standard Growth Curve
- Rely on changes in turbidity in liquid culture
- Do not know number of cells, but can track changes in cell density
- Use spectrophotometer to measure light transmittance through broth
Indirect Method of Measuring Bacterial Growth
Indirect Method of Measuring Bacterial Growth
- Rely on changes in turbidity in liquid culture
- Do not know number of cells, but can track changes in cell density
- Use spectrophotometer to measure light transmittance through broth
Indirect Method of Measuring Bacterial Growth
- Rely on changes in turbidity in liquid culture
- Do not know number of cells, but can track changes in cell density
- Use spectrophotometer to measure light transmittance through broth
–Count cells on special slide
–Automated cell counters
–Serial dilution and viable plate counts
Direct Method of Measuring Bacterial Growth
Direct Method of Measuring Bacterial Growth
–Count cells on special slide
–Automated cell counters
–Serial dilution and viable plate counts
–Provides estimate of viable cells in original sample
–Dilute sample to produce countable number of colonies on plate
–Mathematically calculate estimate of live cells in sample
–Will explore further in lab
•Serial dilution and viable plate counts for measuring bacterial growth
•Serial dilution and viable plate counts
–Provides estimate of viable cells in original sample
–Dilute sample to produce countable number of colonies on plate
–Mathematically calculate estimate of live cells in sample
–Will explore further in lab
–Chemicals that organism needs to synthesize molecules
–C, H, N, O
•Can describe organisms based on how they fulfill these needs
Nutrients
•Carbon is basis of all biological molecules
•Heterotrophs
–Acquire carbon from existing organic molecules
•Autotrophs
–Take in carbon as CO2 (inorganic carbon)
Nutrient Acquisition
–Acquire carbon from existing organic molecules
•Heterotrophs