Quiz 8 - Growth Curve & Temperature Effects

What macronutrients are needed for growth?

C, H, O, N, P, S

What micronutrients are needed for growth?

Trace elements - minerals used in enzymes (Fe, Mg, etc.)

Organic growth factors - required organic molecules the microbe cannot produce

What happens to enzymes at low temperatures?

Slows the reaction rate

What happens to enzymes at high temperatures?

Increases reaction rate until the protein starts to denature

What happens if the pH or ionic concentration of an environment is increased or decreased?

Reduces the reaction rate or potentially cause denaturing

What is the logarithmic growth in the log phase due to?

Reproduction by binary fission (bacteria) or mitosis (yeast)

Lag phase

intense activity preparing for population growth, but no increase in population/cell division

Log phase

logarithmic, or exponential, increase in population

Stationary Phase

Period of equilibrium; microbial deaths equals production of new cells

Death phase

Population is decreasing at a logarithmic rate

What phase is generation time calculated from?

Log phase

How is growth measured?

Measured as an increase in turbidity of a sample, or as an increase in cell #/ increase in CFU

What is plotted on a standard growth curve?

Plotting cell numbers, or turbidity change, over time

What is generation time?

The time required for a microbial population to double

What does the shortest generation time at a specific temperature mean for an organism?

Optimal temperature for growth