Regulation of bacterial metabolism

Question 1

Why regulate metabolism?

Answer 1

conserve energy
conserve nutrients
to produce accurate amounts
to stop wastage
to ensure the preferred nutrient source

Question 2

Enzymes that are not regulated are said to obey

Answer 2

mass action kinetics

where the [conc] of the enzyme and substrates –> determines the ROR

follows MM equation

Question 3

controlling flux:

enzymes that are commonly regulated are those

Answer 3

that catalyse irreversible or very unfavourable reactions

often the RDS

Question 4

methods of regulating metabolism in bacteria (4)

Answer 4

• controlling flux
• branch point regulation
• control of enzyme amount
• control of enzyme activity

Question 5

branch point regulation

Answer 5

a precursor makes 2 or more products, so 2 enzymes ‘compete’ for the substrate

either enzyme can be controlled by other factors which affects the amount of product

eg. A is the precursor, can be made into either B or C by 2 different enzymes. increasing levels of the enzyme that makes C would decrease the amount of B

Question 6

control of enzyme amount is achieved by (2)

Answer 6

control of the production rate

control of the degradation rate

Question 7

control of enzyme activity is achieved by (3)

Answer 7

allosteric regulation (small molecules)
post translational modifications
control of substrate access (through compartmentalisation)

Question 8

Enzyme amount regulation

Answer 8

majority of enzyme regulation is achieved by regulating TRANSCRIPTION

usually at initiation, but sometimes elongation or termination

other ways: mRNA stability, protein turnover

Question 9

Enzyme regulation: initiation and transcription (2)

Answer 9

one component regulators

two component regulators