Environmental control of metabolism

Question 1

Microorganisms

Answer 1

Organisms too small to be seen without magnification

Question 2

Three domains of life and

One example of each

Answer 2

Eukaryotes, Bacteria and Archea
Eukaryotes: animals
Bacteria: antino bacteria
Archea: nanoarcheaota

Question 3

Uses of microbes:

Answer 3

Used in research and industry

Question 4

Why are microbes used in research and industry:

Answer 4

Are easy to culture, they grow and reproduce rapidly.
Their food substrate is often cheap
They produce many products: yoghurt, cheeses, alcohols.
Their metabolism can be controlled and manipulated fairly easily.

Question 5

How is optimum yield of useful products produced by microbes ensured?

Answer 5

They control the environmental conditions during the culture of yeast/bacteria.
In industry large containers which are constantly monitored are used.

Question 6

Small scare growth media for microbes

Answer 6

Agar jelly (solid) in petri dishes or broth (liquid) in flasks.
Both contain all the nutrients needed for growth of the microbes

Question 7

Large scale growth media for microbes

Answer 7

Broth in industrial fermenters.

Contains all nutrients needed for growth of the microbes.

Question 8

Composition of growth media for microbes since they cannot photosynthesise

Answer 8

Energy source - carbohydrate
Building blocks to make new cells - amino acids and nucleotides
Sometimes specific compounds - fatty acids, vitamins etc.
Nutrient may also be provided - beef extract

Question 9

When growing microbes what environmental conditions must be composed?

Answer 9

Aseptic techniques: creating of sterile conditions to avoid contamination
Computing monitoring and control of environmental conditions.

Question 10

Key factors that affect growth

Answer 10

Temperature
Oxygen concentration
pH
Glucose concentration

Question 11

Computer controlled fermenters

Answer 11

Produce huge quantities of products,

If key factors varie they will see this and adjust them so that optimum conditions are kept.

Question 12

Growth;

Answer 12

When rate of synthesis of new organisms material exceeds the rate of breakdown of material.
Involves an irreversible increase in dry biomass.

Question 13

Why is dry biomass used as an indicator of growth rather than fresh biomass?

Answer 13

It’s more reliable since fresh biomass varies depending in water availability.

Question 14

Measuring growth for bacteria and yeast cells -

Answer 14

Increase in numbers of cell number over a period of time

Question 15

Generation / doubling time

Answer 15

Time taken for a cell to divide

Question 16

How is the extent of growth of a microbial culture determined?

Answer 16

By taking samples from the culture and knowing the initial number of cells present

Question 17

Two different types of cell count -

Answer 17

Viable cell count and total cell count

Question 18

Viable cell count

Answer 18

Counts only living microorganisms

Question 19

Total cell count

Answer 19

Counts viable and dead cells

Question 20

Growth curve graph -

Answer 20

log(number of cells) against time
4 parts
Lag phase m=>0
Exponential phase m=>1
Stationary phase m=0
Death phase m=

Question 21

Lag phase

Answer 21

Little to no increase in cell number,, microbes adjust to conditions of the culture and begin to metabolise substrate, may need to induce enzymes, cells will prepare for cell division

Question 22

Exponential phase

Answer 22

Contains the most rapid growth of microbes, growth rate is at a maximum due to plentiful nutrients

Question 23

Stationary phase

Answer 23

Cell production and death are equal to one another, nutrients in culture become depleted and toxic metabolites are produced.

Question 24

Why is the stationary phase sometimes encouraged?

Answer 24

Secondary metabolites (molecules not required for cell growth) are produced, for example antibiotics.

Question 25

Why do microbes produce a secondary metabolite?

Answer 25

They confer an ecological advantage, by allowing the microbes that produce them to outcompete other microorganisms.

Question 26

Death phase

Answer 26

Where lack of substrate and the toxic accumulation of metabolites causes death of cells

Question 27

Which phase shows only viable cell count

Answer 27

Death phase

Question 28

How is pH controlled?

Answer 28

Via the use of a buffer solution

Question 29

Why do cells not divide in lag phase?

Answer 29

Enzymes are induced

Question 30

Why does secondary metabolites give an ecological advantage?

Answer 30

It will kill other bacteria reducing competition for the microorganism.