Key Area 2.6: Environmental control of metabolism in microorganisms

Question 1

Name the 4 phases to microorganism growth?

Answer 1

• Lag phase
• Log phase
• Stationary phase
• Death phase

Question 2

What happens in the lag phase?

Answer 2

In the lag phase of growth the mircoorganisms adjust to the conditions of the culture by including the production of enzymes that metabolise the available substrates. No cell division occurs here.

Question 3

What happens in the log phase?

Answer 3

In the log phase the population doubles with every round of cell division, this is based on the temperature and the culture medium.

Question 4

What happens in the Stationary phase?

Answer 4

In the stationary phase the culture medium becomes depleted and nutrients or oxygen start to run out. Metabolites released might become toxic to the mircoorganism, this could inturn be an advantage to the mircoorganisms in a natural setting. Here the death rate= the birth of the birth rate so no increase in cell population

Question 5

What happens at the death phase?

Answer 5

In the death phase due to the lack of substrate and the toxic build up results in the death rate being greater than the birth rate. At the end of this phase the population of the bacteria may be completely eliminated.

Question 6

What is a precursor?

Answer 6

A precursor is a substance that is acted upon by an enzyme to ensure the production of a desired metabolite later on in the same pathway.

Question 7

What is a inducer?

Answer 7

An inducer is a substance that triggers the production of a specific enzyme, which then produces the desired metabolite

Question 8

What is an inhibitors?

Answer 8

An Inhibitor is used to avoid the breakdown of a required product. They effect the enzyme catalysing the breakdown of the required metabolite by acting competitively or non-competitively.