lecture 28 - microbial population growth Flashcards

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1
Q

How do prokaryotes reproduce?

A

Asexually - via binary vision

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2
Q

What is the closed batch culture system?

A

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

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3
Q

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

A

Lag, exponential, stationary, death

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4
Q

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

A

Lag

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5
Q

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

A

Exponential

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6
Q

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

A

Stationary

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7
Q

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

A

Death

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8
Q

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

A

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.

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9
Q

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

A

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

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10
Q

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

A

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.

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11
Q

What is cryptic growth?

A

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.

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12
Q

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

A

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

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13
Q

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

A

At a static equilibrium

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14
Q

What are the 3 requirements for microbial population growth?

A

Carbon source, energy source, reducing power

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15
Q

Why is a carbon source required for microbial population growth?

A

Carbons provides the building blocks for macro molecular synthesis.

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16
Q

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

A

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

17
Q

How is reducing power utilised in microbial population growth?

A

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

18
Q

How is energy harvested by microbes for growth and function?

A

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

19
Q

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

A

Redox reactions

20
Q

What is catabolism, in terms of metabolism?

A

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

21
Q

What is anabolism, in terms of metabolism?

A

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

22
Q

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

A

Photoautotrophs, chemoautotrophs, photoheterotrophs, chemoheterotrophs

23
Q

What type of bacteria get their carbon by fixing CO2?

A

autotrophs

24
Q

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

A

heterotrophs

25
Q

Where do heterotrophs get their carbon from?

A

Organic compounds

26
Q

Where do autotrophs get their carbon from?

A

The fixing of carbon dioxide.

27
Q

What type of bacteria get energy from light?

A

Phototrophs

28
Q

What type of bacteria get their energy from chemical compounds?

A

Chemotrophs

29
Q

What is a wild type strain?

A

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.

30
Q

What is an auxotroph?

A

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.

31
Q

What is cross feeding, in terms of microbial growth?

A

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.

32
Q

What is a microbiome?

A

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

33
Q

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

A

microbiota

34
Q

What is a culture dependent study?

A

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

35
Q

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

A

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

36
Q

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

A

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

37
Q

What is a culture independent study?

A

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

38
Q

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

A

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

39
Q

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

A

No pure culture, so cannot easily manipulate microbes.