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Microbiology (Bio305) > Chapter 4 > Flashcards

Chapter 4 Flashcards

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1
Q

What are those that must be supplied from the environment for microbial nutrition?

A

Essential Nutrients

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2
Q

What are some examples of Macronutrients?

A

Carbon, Oxygen, Ca2+ etc

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3
Q

What are some examples of micronutrients?

A

Trace elements such as ZN

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4
Q

What are three things that are required for microbial nutrition?

A

Essential Nutrients
Macronutrients
Micronutrients

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5
Q

What do autotrophs do?

A

fix CO2 and assemble into organic molecules (mainly sugar)

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6
Q

What do heterotrophs do?

A

use performed organic molecules

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7
Q

What type of organism obtains energy from chemical reactions triggered by light?

A

Phototrophs

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8
Q

What type of organsim obtains energy from oxidation-reduction reactions?

A

Chemotrophs

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9
Q

What type of organism uses inorganic molecules as a source of electrons?

A

Lithotrophs

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10
Q

What type of organisms use organic molecules?

A

Organotrophs

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11
Q

What is generated when chemical energy is used to pump protons outside of the cell?

A

Membrane potential

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12
Q

What forms because of the H+ gradient plus the charge difference?

A

Proton motive force

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13
Q

What can the potential energy that is stored do?

A
  1. transport nutrients
  2. Drive flagella rotation
  3. Make ATP by the
    F1F0 ATP Synthase
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14
Q

What makes up 79% of Earth’s atmosphere but is unavailable for use by most organisms?

A

N2

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15
Q

What possess nitrogenase, which converts N2 to ammonium ions(NH4+)?

A

Nitrogen Fixers

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16
Q

What oxidizes ammonia to nitrate(NO3-)?

A

Nitrifiers

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17
Q

What converts nitrate to N2?

A

Denitifiers

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18
Q

What are the three ways that selective permeability is achieved?

A 
1. Substrate-specific 
   carrier proteins 
   (permeases) 
2. Dedicated nutrient-
    binding proteins that 
    patrol that 
    periplasmic space
3. Membrane-spanning 
    protein channels or 
    pores
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19
Q

What helps solutes move across a membrane from a region of high concentration to one of lower concentration?

A

Facilitated Diffusion

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20
Q

What is the name for those in which energy released by a driving ion moving down its gradient is used to move a solute up its gradient?

A

Coupled transport systems

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21
Q

What is the name for when two molecules travel in the same direction in a coupled transport system?

A

Symport

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22
Q

What is the name for when the actively transported molecule moves in the direction opposite to the driving ion in a coupled transport system?

A

Antiport

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23
Q

What is the largest family of energy-driven transport system?

A

ABC Transporters

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24
Q

What are specialized molecules secreted to bind ferric ion and transport it into the cell?

A

Siderophores

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25
Q

What is the process that uses energy to chemically alter the substrate during its transport?

A

Group Translocation

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26
Q

What is an example of group translocation in bacteria?

A

PTS (phosphotransferase system)

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27
Q

What are the two main types of culture media used to grow bacteria?

A
  1. Liquid or broth
  2. Solid (usually gelled
    with agar)
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28
Q

What are the two ways pure colonies are isolated?

A
  1. Dilution Streaking]

2. Spread Plate

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29
Q

What is dilution streaking?

A

a loop is dragged across the surface of an agar plate

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30
Q

What is a spread plate?

A 
1. Tenfold serial dilutions 
    are performed on a 
    liquid culture
2. A small amount of 
    each dilution is then 
    plated
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31
Q

What type of media is nutrient rich but poorly defined?

A

Complex media

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32
Q

What type of media contains only those nutrients that are essential for growth of a given microbe?

A

Minimal defined media

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33
Q

What type of media is a complex media to which specific blood components are added?

A

Enrichment Media

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34
Q

What type of media favors the growth of one organism over another?

A

Selective media

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35
Q

What type of media exploits differences between two species that grow equally well?

A

Differential Media

36
Q

What is MacConkey medium?

A
  1. Growing only Gram
    Negative bacteria
  2. LAC(+) or LAC(-)
37
Q

What are specific nutrients not required by other species?

A

Growth Factors

38
Q

Why can we still not know how to grow some microbes in the lab?

A

Some species have adapted so well to their natural habitats that we still do not know how to grow them in the lab

39
Q

How can microorganisms be counted directly?

A

by placing dilutions on a special microscope slide called a Petroff-Hausser counting chamber

40
Q

What does a fluorescence-activated cell sorter (FACS) or flow cytometer do?

A

an electronic technique that not only counts but also separates populations of bacterial cells according to their distinguishing properties

41
Q

What is defined as being capable of replicating and forming a colony on a solid medium?

A

a viable bacterium

42
Q

What is the pour plate method?

A

a way to count viable cells

43
Q

Microorganisms can be counted indirectly via?

A

biochemical assays of cell mass, protein content, or metabolic rate

44
Q

What are three rules for colony counting?

A
  1. You cannot measure cell size or growth
    phase.
  2. Same species produce a single colony by
    multiple cells
  3. You always underestimate the cell number
45
Q

How do most bacteria divide?

A

binary fission

46
Q

What is an asymmetrical way that bacteria divide?

A

budding

47
Q

What is a rate of increase in cell numbers or biomass, and is proportional to the population size at a given time?

A

growth rate

48
Q

If a cell divides by binary fission, the number of cells is proportional to?

A

2n

49
Q

What does n represent?

A

the number of generations

50
Q

What is the generation time?

A

the time it takes for a population to double.

51
Q

What is Nt = N0 x 2n?

A
  1. Nt is the final cell number
  2. N0 is the original cell number
  3. n is the number of generations
  4. This is the formula for binary fission
52
Q

What type of growth never lasts indefinitely?

A

Exponential Growth

53
Q

What are some characteristics of a batch culture?

A
  1. closed system(in a flask nothing can go in
    or out)
  2. The simplest way to model the effects of a changing environment is to culture bacteria
54
Q

What do the changing conditions in the batch culture affect?

A

greatly affects bacterial physiology and growth

55
Q

What does batch culture illustrate?

A

the ability of the bacteria to adapt to their environment

56
Q

What are the phases in a bacterial growth curve?

A
  1. Lag Phase
  2. Log Phase
  3. Stationary Phase
  4. Death Phase
57
Q

What happens in the lag phase?

A

Bacteria are preparing their cell machinery for growth

58
Q

What happens in the log phase?

A

Growth approximates an exponential curve

59
Q

What happens in the stationary phase?

A

Cells stop growing and shut down their growth machinery while turning on stress responses to help retain viability

60
Q

What happens in the Death phase?

A

Cells die with a “half-life” similar to that of radioactive decay, a negative exponential curve

61
Q

What is quarum sensing?

A

-The regulation of gene expression in
response to fluctuations in cell-population
density
-Signals other cells to do an action
-happens late in the log phase (to tell the
cells to stop growing)

62
Q

What culture is when all cells in a population achieve a steady state?

A

continuous culture

63
Q

What does continuous culture allow for?

A

detailed study of bacterial physiology

64
Q

What is the main characteristic of Continuous culture?

A

Open system

65
Q

What is a chemostat?

A
  • an example of a continuous culture
    -ensures logarithmic growth by constantly
    adding and removing equal amounts of
    culture media.
66
Q

What in the human body is similar to chemostat?

A

the gastrointestinal tract

67
Q

What does a continuous culture graph look like?

A

see slide 53

68
Q

What are specialized, surface-attached communities called?

A

biofilms

69
Q

What are characteristics of biofilms?

A

can be constructed by one or multiple species and can form on a range of organic or inorganic surfaces.

70
Q

True or false. Bacterial biofilms grow when nutrients are plentiful.

A

True

71
Q

What happens to biofilms when nutrients become scarce?

A

individuals detach from the community to forage for new sources of nutrients.

72
Q

What is a benefit of multiple bacteria forming a biofilm together?

A

-act as a multicellular organism

73
Q

What is a common example of a biofilm?

A

teeth plaque

74
Q

Chemical signals enable bacteria to communicate(via quorum sensing) and in some cases can form…?

A

biofilms

75
Q

What are three attributes that go into biofilm development?

A
  1. adherence of cells to a substrate
  2. formation of microcolonies
  3. the formation of complex channeled
    communities that generate new planktonic
    cells
76
Q

What are the 5 steps in biofilm development?

A
  1. Attachment to monolayer via flagella
  2. Microcolonies
  3. Exopolysaccharide production (EPS)
  4. Mature biofilm
  5. Dissolution and dispersal

Repeats again

77
Q

What do sessile(nonmoving) cells do in a biofilm do?

A

-chemically talk to each other in order to build microcolonies and keep water channels open

78
Q

What causes bacteria to undergo complex molecular reprogramming that includes changes in cell structure?

A

environmental stress

79
Q

Clostridium and Bacillus reproduce by?

A

species can produce dormant spores that are heat resistant

80
Q

What is an asymmetrical cell division process that produces a forespore and ultimately an endospore?

A

An 8-hour genetic program initiated by starvation

81
Q

What does Anabaena differentiate into?

A

heterocysts

82
Q

What does differentiating into heterocysts allow it to do?

A

fix nitrogen anaerobically while maintaining oxygenic photosynthesis

83
Q
  1. Dipicolinic acids + Ca2+
A

~ 10% of dry wt.
-Reduce water contents in the endospore
(dehydration)

84
Q
  1. Small Acid-Soluble Proteins (SASP)
A
  • to protect spore’s DNA

- To provide energy for germination

85
Q

What is the enzyme that causes N2 fixation?

A
  • nitrogenase (oxygen-sensitive)

Microbiology (Bio305) (7 decks)

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