Metabolism and Survival - Environmental Control of Metabolism

Question 1

aseptic

techniques

Answer 1

used to try to maintain sterile conditions and eliminate contaminants (competitors) when working with microorganisms

Question 2

biosynthesis

Answer 2

• building up of a complex molecule from simpler ones
• molecules required for biosynthsis in microorganisms include: amino acids, vitamins, and fatty acids

Question 3

fermenter

Answer 3

• container used to culture microorganisms on a large scale to obtain a useful product(s)
• variations from optimum conditions are picked up by sensors/probes (pH, oxygen, carbon dioxide) and are adjusted by a computer

Question 4

(mean) generation time

Answer 4

(average) time taken for a population of cells to double in number

Question 5

growth

Answer 5

• occurs when the rate of synthesis of organic material exceeds the rate of breakdown of material
• irreversible increase in dry biomass

Question 6

growth medium

Answer 6

• substance used to culture microorganisms
• nutrient agar - solid jelly which microbes grow on the surface of
• broth - nutrient rich liquid used in industrial fermenters

Question 7

primary

metabolite

Answer 7

metabolite made by a microbe which is essential to its growth

Question 8

secondary

metabolite

Answer 8

• metabolite made by a microbe that is not essential for the growth of the microbe
• the metabolite may confer an ecological advantage which allows them to outcompete other microorganisms e.g. antibiotics

Question 9

viable

cell count

Answer 9

counts only living microorgansims

Question 10

total

cell count

Answer 10

counts viable and dead cells

Question 11

lag

phase

Answer 11

• cells adjust to the growth medium and new conditions
• begin to metabolise substrate, induce enzymes and prepare for division
• little to no increase in cell number

Question 12

exponential (logarithmic)

phase

Answer 12

maximum / most rapid growth of microorganisms due to plentiful nutrients

Question 13

stationary

phase

Answer 13

• cell production and death are equal - population remains steady
• nutrients in growth medium become depleted
• toxic (secondary) metabolites are produced

Question 14

death

phase

Answer 14

lack of nutrients and/or oxygen and accumulation of toxic metabolites increases death rate reducing population

Question 15

using microorganisms

why are they useful?

Answer 15

• highly adaptable due to wide range of niches
• can use a variety of metabolites to produce a range of useful products
• easy to cultivate, control and manipulate their metabolism
• have rapid growth speeds