13 Questions
What is the characteristic of the death phase in bacterial growth?
Cell death slower than exponential growth
Which method is better for counting viable bacterial cells?
Solid media
What term is used to describe the time it takes for a bacterial population to double in number?
Generation time
Which of the following can be used to count larger cells such as fungi and protozoa?
Coulter counter
Which technique is not mentioned for measuring bacterial growth?
Batch culture
What is required for bacterial replication to produce two equivalent daughter cells?
Sufficient metabolites and cascade of regulatory events
What happens as the cell membrane grows during binary fission?
Daughter chromosomes are pulled apart
What characterizes the exponential (log) phase of bacterial growth?
Constant rate of growth at the maximal rate possible
What usually triggers the stationary phase in bacterial growth?
Depletion of essential nutrients and accumulation of waste products
What is the interval for the formation of two cells from one called?
Generation (doubling) time
What happens during the lag phase of bacterial growth?
Cells may need to resynthesize essential constituents and recover from damage
What is NOT a characteristic of the stationary phase in bacterial growth?
Rapid increase in cell number
How long does cell division usually take place after replication completes in E. coli?
20 minutes
Study Notes
Bacterial Growth Phases
- Bacterial growth consists of four phases: lag, exponential, stationary, and death
- Each phase is characterized by distinct growth patterns and cellular activities
Lag Phase
- Initial phase of growth where cells adapt to new environment and recover from damage
- Cells resynthesize essential constituents, repair damage, and adapt to new medium
- Length of lag phase varies depending on bacterial conditions and medium
Exponential Phase
- Phase of rapid growth where cells divide exponentially
- Characterized by constant rate of growth and maximal rate of cell division
- Influenced by temperature, culture medium, and genetic characteristics
- Used in biochemical and physiological studies
Stationary Phase
- Phase where growth slows down due to depletion of essential nutrients and accumulation of waste products
- No net increase or decrease in cell number
- Typically occurs at a population level of 10^8/ml
- Dependent on nutrient availability, physical conditions, and buildup of toxic waste products
Death Phase
- Phase of decline in cell population due to environmental factors
- Cell death occurs at a slower rate than exponential growth and follows a logarithmic pattern
- Growth curve characteristics reflect events in a population of cells
Binary Fission
- Bacterial replication process resulting in two equivalent daughter cells
- Requires sufficient metabolites and a cascade of regulatory events
- Cell cycle involves replication of genetic material and cell division, but not always at the same rate
- Involves the formation of a septum and the separation of daughter chromosomes
Cell Cycle
- Cell cycle involves the replication of genetic material and cell division
- In E. coli, cell division usually takes place 20 minutes after replication has finished
- Newly formed DNA is attached to adjacent sites on the plasma membrane and initiates a cross wall or septum growth and division of the two cells
Measurement of Growth
- Cell counts can be performed using counting chambers, coulter counters, and spectrophotometry
- Other methods include spread plate and pour plate techniques, membrane filtration systems, and flow cytometry
This quiz covers the characteristics of bacterial growth, including the exponential and death phases, and how it can be demonstrated on solid and liquid culture media.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
