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Bacteriology and Mycology > Microbiology II > Flashcards

Microbiology II Flashcards

(64 cards)

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1
Q

What are the inorganic parts of microbes?

A

nitrogen (N),
carbon (C),
oxygen (O),
hydrogen (H),
phosphorus (P),
sulfur (S),
sodium (Na),
magnesium (Mg),
potassium (K),
calcium (Ca),
iron (Fe) and other

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2
Q

How does the cell wall of gram positive and gram negative bacteria compare?

A

gram positive: thick peptioglycan layer, no outer membrane
gram negative: thin peptidoglycal layer, possess an outer membrane

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3
Q

What gram-bacteria has a more complex cell wall?

A

gram negative

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4
Q

Which dies do gram positive and gram negative bacteria retain?

A

gram positive: blue/purple –> retains crystal violet/iodine

gram negative: red/pink –> safranin

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5
Q

State examples of gram negative bacteria.

A
  • E .coli,
  • Pseudomonas aeruginosa,
  • Salmonella spp.
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6
Q

State examples of gram positive bacteria.

A
  • Listeria monocytogenes
    Bacillus cereus
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7
Q

What does microbial growth refer to?

A

The increase in a population of microbes rather than an increase in size of an individual.

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8
Q

What is the result of microbial growth?

A

a discrete colony

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9
Q

What is a discrete colony?

A

An aggregation of cells arising from single parent cell.

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10
Q

What results in growth?

A

reproduction

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11
Q

Growth of most microorganisms occurs by what process?

A

binary fission

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12
Q

How do bacterial cells divide?

A
  • exactly in half
  • geometric procression doubling the cell number
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13
Q

What is the average doubling time of bacteria?

A
  • Escherichia coli: 12.5 min
  • Vibrio cholerae: 13 min (can kill a man within 12 h)
  • Mycobacterium tuberculosis: 24 h (develop symptom after months)
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14
Q

What are mycoplasmas?

A
  • prokaryotes
  • class: Mollicutes
  • smallest free-living, self-replicating microorganisms.
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15
Q

How do mycoplasmas reproduce?

A

by binary fission

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16
Q

What may occur to mycoplasmas during reproduction?

A

Cytoplasmic division frequently may** lag genome
replication**, resulting in formation of multinuclear filaments.

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17
Q

What do mycoplasma colonies resemble? (life-situation)

A

fried-egg

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18
Q

How does Chlamydia reproduce?

A
  • chlamydiae share a developmental cycle
  • alternate between the extracellular,
    (infectious elementary body) and the intracellular, (non-infectious reticulate body).
  • INCLUSION: elementary bodies enter mucosal cells and differentiate into reticulate bodies in a membrane bound compartment
    -** BINARY FISSION**: reticulate bodies then divide by binary fission within the endocytic vacuole.
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19
Q

What is the “growth curve”?

A

In laboratory studies, populations typically display a predictable pattern over time.
1. lag- size increases, number remains the same
2. log- number of cell increases exponentially
3. stationary- cell number remains the same
4. death/decline phase- cell number decreases

steep up, plateau, steep down

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20
Q

What must occur for the exponential phase to continue?

A

Cells must have adequate nutrients and a favorable environment.

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21
Q

What does the stationary phase equal to?

A

The rate of cell death caused by depleted nutrients and
O2, excretion of organic acids and pollutants.

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22
Q

Why does death phase occur?

A

Limiting factors intensify, killing cells exponentially in their own wastes.

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23
Q

How is growth measured by direct counting?

A
  • change in the number of cells over time,
  • cell counts done microscopically measure the total number of cells in a population,
  • viable cell counts (plate counts) measure only the living, reproducing population.
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24
Q

How is growth measured by indirect counting?

A
  • turbidity measurements (indirect but very rapid and useful method)
  • BUT, to relate a direct cell count to a turbidity value, a standard curve must first be established.
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25
What can be used for turbidimetric measurements of cell mass?
a spectrophotometer or calorimeter
26
How can a spectrophotometer be used to determine turbidity?
By measuring the amount of light that passed through a suspension of cells. More cells = more turbidity = less light passing through the suspension
27
What is a simple way of describing turbidity?
cloudiness
28
What are the different nutrition types?
**CARBON SOURCE:** **Heterotroph ** - must obtain carbon in an organic form made by other living organisms such as proteins, carbohydrates, lipids and nucleic acids. **Autotroph**- an organism that uses CO2, an inorganic gas as its carbon source, not nutritionally dependent on other living things.
29
What are the ways of gaining an energy source?
**chemotrophs** – gain energy from chemical compounds **phototrophs** – gain energy through photosynthesis
30
What are the types of autotrophic bacteria?
chemoautotropic photoautotropic
31
What are the types of heterotrophic bacteria?
parasitic saprophitic symbiotic
32
What are the two forms of microbial metabolism?
1. **Catabolism (Dissimilation)**: - breakdown organic substrates (carbohydrates, lipids, proteins) to yield metabolic energy for growth and maintenance. 2. **Anabolism (Assimilation)**: - assimilatory pathways for the formation of key intermediates and then to end products (cellular components).
33
What processes is metabolism made up of?
catabolism and anabolism
34
What are the principal features of passive transport?
- no energy required; - substances exist in a gradient (move from high to low conc.) eg. - diffusion - osmosis (diffusion of water) - facilitated diffusion (requires a carrier)
35
What are the principal features of active transport?
- requires energy - requires carrier proteins; - gradient independent active transport - group translocation - transported molecule is chemically altered.
36
In what direction does water move in osmosis?
isotonic solution: no net movement hypotonic solution: water moves into the cell hypertonic solution: water moves outside the cell
37
What is aerobic respiration?
The process by which organisms use oxygen to turn fuel, such as fats and sugars, into chemical energy.
38
What is the growth pattern of the following: 1. Obligate aerobe 2. Obligate anaerobe 3. Microaerophile 4. Aerotolerant anaerobe 5. Facultative anaerobe/aerobe
1. on top 2. on bottom 3. on top, less on very top 4. everywhere 5. everywhere, most on top
39
What is an aerobe?
A microorganism whose growth requires the presence of air or free oxygen.
40
What is the difference between an aerobe and an obligate aerobe?
**aerobe**: utilizes oxygen and can detoxify it. **obligate aerobe**: cannot grow without oxygen.
41
What is an anaerobe?
A microorganism that grows only or best in the absence of free oxygen.
42
What is the difference between an anaerobe and an obligate anaerobe?
**anaerobe**: does not utilize oxygen. **obligate anaerobe**: lacks the enzymes to detoxify oxygen so cannot survive in an oxygen environment.
43
What are microaerophiles?
- need oxygen to grow, - optimum oxygen concentration (21%) for an organism is the oxygen level that promotes the fastest growth rate.
44
What are facultative anaerobes?
- grow with or without oxygen - metabolise energy aerobically or anaerobically - gather mostly at the top because aerobic respiration generates more ATP than fermentation.
45
Why do facultative anaerobes gather mostly at the top of the test tube?
Aerobic respiration generates more ATP than fermentation (anaerobic respiration.)
46
What are aerotolerant anaerobic bacteria?
- do not use oxygen to make cellular energy (perform anaerobic respiration/fermentation) - survive in the presence of oxygen (unlike some other anaerobic bacteria)
47
What are capnophiles?
- microorganisms that thrive in the presence of high concentrations of carbon dioxide (CO2). - some may have a metabolic requirement for carbon dioxide, - others compete more successfully for resources under these condition (Campylobacter spp.)
48
What happens to toxic forms of oxygen? State one example.
- formed as the result of respiration - enzymes can neutralize most Hydrogen peroxide (toxic oxygen) neutralized by catalase (enzyme)
49
What can be formed in the cell as a result of respiration?
toxic oxygen forms
50
State the toxyc oxygen forms and their breakdown enzymes.
hydrogen peroxide (H2O2) --> catalase, peroxidase oxygen ion (O-) --> superoxide dismutase, superoxide dismutase+catalase, superoxide reductase
51
In what states can culture media be found?
liquid (called **broth**) **semi-solid** solid (**agar**)
52
How are media solidified?
By the addition of solidifying agents such as agar (varying the concentration of agar will yield varying degrees of solidification).
53
What are the different forms of media?
- Ordinary (simple) media - Minimal media - Special media (serum agar, serum broth, coagulated serum, potatoes, blood agar, blood broth, etc.). - Elective media - Enriched media - Transport media - Differential diagnostic media
54
What are the forms of differential diagnostic media?
- proteolytic action; - fermentation of carbohydrates (Hiss media); - haemolytic activity (blood agar); - reductive activity of microorganisms; - media containing substances - assimilated only by certain microbes.
55
How can a liquid culture in a tube, bottle or flask be inoculated?
by touching with a charged loop
56
Which part of metabolism can help in the identification of bacteria?
The capacity to form pigment and power of haemolysis is help for classification of bacteria.
57
What are the most important biochemical reactions used in bacteria identification?
- sugar fermentation (gas) - inole production (red top) - hydrogen sulfide production (black bottom) - catalase test (bubbles) - API-20 "Bio Merieux" (France) strip test
58
What is the visible reaction of sugar fermentation?
gas production
59
What is the visible reaction of indole production?
red top
60
What is the visible reaction of hydrogen sulfide production?
black bottom
61
What is the visible reaction of the catalase test?
formation of bubbles
62
What is antigenic analysis?
- using specific sera we can identify microorganism by agglutination reaction - eg. if bacteria begin to clump
63
What is bacteriophage typing?
Phage brings about lysis of susceptible bacterial cells.
64
What laboratory animal models are usually used for pathogenic tests?
guinea pigs, rabbits, rats, and mice.

Bacteriology and Mycology (9 decks)

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