6. environmental control of metabolism

Question 1

describe microorganisms

Answer 1

can be archaea, bacteria and some species of eukaryotes. e.g. algae and yeast.

use a wide variety of substrates for metabolism and produce a range of products from their metabolic pathways. (e.g. production of biodiesel from algae)

are used in industry because of their adaptability, ease of cultivation and speed of growth

Question 2

what raw materials do microorganisms need for biosynthesis

Answer 2

amino acids (to make proteins/polypeptides), fatty acids and vitamins

Question 3

what is biosynthesis

Answer 3

the production of complex molecules within living organisms or cells

Question 4

what are the two forms of basic growth media

Answer 4

broth and agar

Question 5

Explain the difference between raw materials required for biosynthesis and those required as an energy source

Answer 5

For biosynthesis, the raw materials are used to build up complex molecules within living organisms or cells whereas an energy source is used to release energy from glucose

Question 6

what are the correct culture conditions

Answer 6

-control of temperature
-sterility
-pH
-gaseous environment (oxygen levels)
-light

Question 7

why are fermenters steam cleaned

Answer 7

Sterile conditions in fermenters reduce competition with desired micro-organisms for nutrients and reduce the risk of spoilage of the product.

Question 8

what are the 4 phases on the growth curve

Answer 8

-lag phase
-log/exponential phase
-stationary phase
-death phase

Question 9

describe what happens in the lag phase

Answer 9

enzymes are induced (increase in number and start) to metabolise substrates.

(no microorganisms produced yet as other chemical reactions (respiration) are taking up time so there is no time to synthesise new cells)

Question 10

describe what happens in the log/exponential phase

Answer 10

contains the most rapid growth of micro-organisms due to plentiful nutrients. (respiration releases energy to build up from molecules produced in lag phase) log/exponential phase

Question 11

describe what happens in the stationary phase

Answer 11

The stationary phase occurs due to the nutrients in the culture media becoming depleted and the production of toxic metabolites.

Secondary metabolites are also produced, such as antibiotics. (so that they can kill competing microorganisms

Question 12

describe what happens in the death phase

Answer 12

The death phase occurs due to the toxic accumulation of metabolites or the lack of nutrients in the culture

Question 13

what is a viable cell count

Answer 13

Viable (live) cell counts involve counting only the living micro-organisms

Only viable cell counts show a death phase where cell numbers are decreasing.

Question 14

what is a total cell count

Answer 14

total cell counts involve counting viable and dead cells