lecture 28 - microbial population growth

Question 1

How do prokaryotes reproduce?

Answer 1

Asexually - via binary vision

Question 2

What is the closed batch culture system?

Answer 2

A system in which cells can be grown in a closed environment, with limited nutrients only provided initially.

Question 3

What are the 4 key phases of growth in a closed batch culture system?

Answer 3

Lag, exponential, stationary, death

Question 4

What is the first growth stage of the closed batch culture system?

Answer 4

Lag

Question 5

What is the second growth stage of the closed batch culture system?

Answer 5

Exponential

Question 6

What is the third growth stage of the closed batch culture system?

Answer 6

Stationary

Question 7

What is the fourth and final growth stage of the closed batch culture system?

Answer 7

Death

Question 8

What is the lag phase of a closed batch culture system?

Answer 8

When very little growth is observed because time is required to get bio synthetic reactions up and ready and for the organisms to adapt to their new conditions.

Question 9

What is the exponential phase of a closed batch culture system?

Answer 9

Phase when cells are actively dividing with aid of nutrients, with no factors limiting their growth. Population doubles over a constant time interval, under ideal conditions

Question 10

What is the stationary phase of a closed batch culture system?

Answer 10

Phase when there is no net cell growth (cryptic growth) All nutrients are used up and organisms are surviving and replicating by consuming dead/lysed cells. The rate of growth and death is constant.

Question 11

What is cryptic growth?

Answer 11

A phenomenon observed in a closed batch culture system, where there appears to be no bacterial growth, or even a decline, but growth still occurs at a rate equal or less than the rate of death of cells.

Question 12

What is the death phase of a closed batch culture system?

Answer 12

When the system is no longer viable, so cells begin to die at a rapid rate, and the equilibrium is skewed towards death.

Question 13

How can the culture at the stationary phase in a closed batch culture system be described?

Answer 13

At a static equilibrium

Question 14

What are the 3 requirements for microbial population growth?

Answer 14

Carbon source, energy source, reducing power

Question 15

Why is a carbon source required for microbial population growth?

Answer 15

Carbons provides the building blocks for macro molecular synthesis.

Question 16

Why is an energy source required for microbial population cell growth?

Answer 16

Energy stored in electrons is used to drive anabolic and catabolic reactions in the cell.

Question 17

How is reducing power utilised in microbial population growth?

Answer 17

NAD+/NADP+ can be reduced to carry electrons in biological processes

Question 18

How is energy harvested by microbes for growth and function?

Answer 18

Chemical energy stored in bonds is released and captured by ATP when bonds in fuels, such as glucose, is broken.

Question 19

What is the overall type of reaction that allows for the transfer of energy in a bacteria?

Answer 19

Redox reactions

Question 20

What is catabolism, in terms of metabolism?

Answer 20

Generating energy by breaking big molecules down into building blocks and releasing chemical energy.

Question 21

What is anabolism, in terms of metabolism?

Answer 21

Using energy and building blocks/monomers to build larger molecules and store chemical energy.

Question 22

What are the 4 types of bacteria, in terms of their energy and carbon source?

Answer 22

Photoautotrophs, chemoautotrophs, photoheterotrophs, chemoheterotrophs

Question 23

What type of bacteria get their carbon by fixing CO2?

Answer 23

autotrophs

Question 24

Why type of bacteria rely on extracellular sources of carbon - i.e. cannot fix their own?

Answer 24

heterotrophs

Question 25

Where do heterotrophs get their carbon from?

Answer 25

Organic compounds

Question 26

Where do autotrophs get their carbon from?

Answer 26

The fixing of carbon dioxide.

Question 27

What type of bacteria get energy from light?

Answer 27

Phototrophs

Question 28

What type of bacteria get their energy from chemical compounds?

Answer 28

Chemotrophs

Question 29

What is a wild type strain?

Answer 29

A microbe strain that has all the essential genes to be grown by itself in pure culture - is not reliant on outside sources of nutrients.

Question 30

What is an auxotroph?

Answer 30

A microbe that is defective in one or more essential genes that means it will not grow/cannot be cultured without limiting factors being added.

Question 31

What is cross feeding, in terms of microbial growth?

Answer 31

When one species gains the metabolic products/byproducts of another species allowing for the coexistence of microbes that cannot metabolise everything they need to survive on their own.

Question 32

What is a microbiome?

Answer 32

A complete collection of micro-organisms and their gene pool that exist within a specific environment.

Question 33

What is the name for an individual microbe within a microbiome?

Answer 33

microbiota

Question 34

What is a culture dependent study?

Answer 34

A method to culture specific microbes so their phenotypes can be easily accessed and their conditions can easily be manipulated.

Question 35

What are the pros of a culture dependent method of microbe study?

Answer 35

Allows access to phenotype of specific organism. Can see how changing conditions affects a specific organism.

Question 36

What are the cons of a culture dependent method of microbe study?

Answer 36

Not all organisms can be cultured, too many species to grow them all, precise conditions must be met, doesn’t it match real world conditions

Question 37

What is a culture independent study?

Answer 37

Study where bacteria are not cultured, but genetic sequencing and metabolic profiling are used to study all of the microbes in a sample.

Question 38

What are the pros of a culture independent method of microbe study?

Answer 38

Allows access to microbial genotypes, can study many organism ad how they interact, can study non-culturable organisms.

Question 39

What are the cons of a culture dependent method of microbe study?

Answer 39

No pure culture, so cannot easily manipulate microbes.