Microbial Growth Flashcards
What is microbial growth?
An increase in the number of cells, not the size of the cells
What is a microbial colony?
Groups of cells (large enough to be seen without a microscope) of hundreds of thousands of cells, or populations of billions of cells
There can be different shapes to microbial colonies. List five.
Circular, Rhizoid, Irregular, Filamentous and Spindle
There can be different margins to microbial colonies. List six
Entire, Undulate, Lobate, Curled, Rhizoid and Filamentous
There can be different elevations to microbial colonies. List five.
Flat, raised, convex, pulvinate and umbonate
What are the four methods of reproduction in prokaryotes?
Budding, binary fission, conidiospores and fragmentation of filaments
Explain the overview of mitosis.
The cell elongates and the DNA is replicated
The cell wall and plasma membrane begin to constrict
A cross-wall forms, completely separating the two DNA copies
The cell separates
What is the generation time?
The time required for a cell to divide
The generation time varies among organisms, what does it depend on and how long can it take?
The generation time depends on environmental conditions. It is between 1-3 hours for most bacteria but others might require more than 24 hours
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What are the four phases of growth?
Lag phase, log phase, stationary phase and death phase
What happens in the lag phase?
The number of cells changes very little
What happens in the log phase?
The cells divide and enter a period of growth
What happens in the stationary phase?
The growth rate slows
What happens in the death phase?
The number of deaths exceeds the number of new cells
The requirements of growth split into two categories what are these?
Physical requirements and chemical requirements
List three physical requirements bacteria rely on
Temperature, pH and osmotic pressure
List some chemical requirements bacteria require
Carbon, nitrogen, sulphur, phosphorous, trace elements, oxygen and organic growth factors
What are psychrophiles?
Cold loving microbes
What are mesophiles?
Moderate temperature loving microbes
What are thermophiles?
Heat loving microbes
