Key Area 6: Environmental Control Of Metabolism

Question 1

What are three examples of microorganisms?

Answer 1

• bacteria
• algae
• fungi

Question 2

What are the five properties of microorganisms?

Answer 2

• a vast range of substrates for metabolism
• a diverse range of products are made from metabolic pathways
• adaptability
• easy to cultivate
• quick growth rate

Question 3

Where can microorganisms derive energy?

Answer 3

Chemical energy (respiration)
Light energy (photosynthesis)

Question 4

What is a simple growth medium?

Answer 4

• specific ingredients

- glucose, amino acids, fatty acids

Question 5

What is a complex medium?

Answer 5

• non-specific ingredients

- glucose, vitamins, beef extract

Question 6

What is aseptic technique?

Answer 6

Maintaining sterile conditions which is used when growing bacteria to prevent cross-contamination

Question 7

What is industrial fermentation?

Answer 7

When vast quantities of microorganisms are grown to produce huge quantities of useful product such as antibiotic

Question 8

What are conditions that would be monitored in an industrial fermenter?

Answer 8

• temperature
• oxygen concentration
• pH

Question 9

What happens if oxygen level drops too low in the fermenter?

Answer 9

Computers get messages from sensors and they bring levels back up to normal

Question 10

What happens if temperature in the fermenter is too high or too low?

Answer 10

Sensors pick it up and tell the computer which corrects it usually by passing more or less water through the cooling jet

Question 11

What happens to keep pH levels constant?

Answer 11

A buffer is added

Question 12

What is doubling/generation time?

Answer 12

The time it takes to for a cell to divide

Question 13

What are the four phases in the bacteria growth graph?

Answer 13

• lag
• log
• stationary
• death

Question 14

Describe the lag phase

Answer 14

• little to no growth

- enzymes induced and preparing for growth

Question 15

Describe the log phase

Answer 15

Maximum rate of division

Question 16

Describe the stationary phase

Answer 16

Secondary metabolites and toxins build up

Limiting factors

Question 17

Describe the death phase

Answer 17

Toxins are killing microbes

Question 18

What is exponential growth?

Answer 18

When the cells are doubling in a small amount of time (maximum division rate)

Question 19

Why is semi-logarithmic graph paper to be used?

Answer 19

To show the enormous number cells in a culture

Question 20

What are primary metabolites and where are the produced?

Answer 20

Primary metabolites are produced in the lag phase and are useful for growth as energy is used and substrate is broken down

Question 21

What are secondary metabolites and where are they produced?

Answer 21

Stationary metabolites are produced in the stationary phase and are not useful for growth but give an organism an ecological advantage

Question 22

Why do secondary metabolites give an ecological advantage?

Answer 22

They prevent competition ?

Question 23

What three ways can a microorganisms’ metabolism be manipulated?

Answer 23

• precursor
• inducer
• inhibitor

Question 24

What is a precursor?

Answer 24

Added when there is a continuous supply of a substance needed earlier in an enzyme controlled process to produce lots of end product

Question 25

What is an inducer?

Answer 25

Added when a continuous supply of a substance is needed to allow a particular enzyme to remain active

Question 26

What is an inhibitor?

Answer 26

Added when a continuous supply of an inhibitor is needed to prevent the useful metabolite being broken down