Bacterial Growth and Metabolism

Flashcards reviewing bacterial growth, metabolism, and influencing factors.

What is bacterial growth defined as?

An increase in the number of cells, not cell size.

What type of reproduction is bacterial growth?

Asexual reproduction (binary fission).

What is binary fission?

The process of a bacterium dividing into two daughter cells.

What does one bacterial cell become?

A colony of millions of cells.

What is generation time?

The time it takes for a single cell to grow and divide.

What is the average generation time for bacteria?

1-3 hours.

Roughly, how quickly can Escherichia coli divide?

Every 20 minutes.

What is an example of a bacterium with a much slower generation time?

Mycobacterium (12-24 hours).

What are the four phases of bacterial growth?

Lag phase, Log phase, Stationary phase, Decline phase

What primarily occurs during the Lag Phase?

Cells synthesize molecules necessary for replication, essential cofactors, ribosomes and new enzymes.

What characterizes the Log phase?

Cells grow most rapidly, doubling at a fairly constant rate.

During the log phase, is the number of cells produced more or less than the number of cells dying?

Number of cells produced > Number of cells dying

What characterizes the Stationary Phase?

Number of cells produced = Number of cells dying

What characterizes the Decline phase?

Number of cells dying > Number of cells produced

Why is controlling microbial growth important?

For infection control and growth of industrial/biotech organisms.

List five factors that influence microbial growth?

Nutrition, Oxygen, Temperature, pH, Osmotic Pressure

What four elements make up 95% of the dry weight of a bacterium?

Carbon, Oxygen, Hydrogen, Nitrogen

How do bacteria obtain hydrogen and oxygen?

From water.

How do bacteria usually obtain carbon?

From degradation of carbohydrates by oxidation or fermentation.

How do bacteria obtain nitrogen?

From ammonia in the environment or proteins via deamination.

What are three examples of growth factors?

Amino acids, purines/pyrimidines, and vitamins.

What is an autotrophic bacteria and what carbon source does it use?

Bacteria that uses CO2 as its carbon source.

What is a heterotrophic bacteria and what carbon source does it use?

Bacteria that obtain carbon in an organic form (proteins, lipids, etc.).

What is an obligate aerobe?

An organism that requires O2.

What is an obligate anaerobe?

An organism that dies in the presence of O2.

What is a facultative anaerobe?

An organism that can use O2 but also grow without it.

What does the enzyme superoxide dismutase do?

Partially detoxifies superoxide.

What tempature range to psychrophiles grow in?

Psychrophiles, grow between 0°C and 20–30°C

What is the optimal pH range for neutrophiles

Grow at pH 5.5 to 8.5.

How do bacteria respond to high salt concentrations?

Water loss and plasmolysis.