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MCB 4403 > Lecture 4 > Flashcards

Lecture 4 Flashcards

1
Q

microbial growth

A

increase in the number of cells through binary fission, asexual reproduction, cloning, etc.

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2
Q

microbe populations increase….

A

exponentially

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3
Q

growth cycle of bacteria: lag phase

A

cells synthesizing materials and not dividing

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4
Q

growth cycle of bacteria: log phase

A

exponential growth

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5
Q

growth cycle of bacteria: stationary phase

A

cells no longer growing

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6
Q

growth cycle of bacteria: death phase

A

lol they die

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7
Q

photoautotroph

A

uses light and CO2 to make energy (plants)

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8
Q

photoheterotroph

A

uses light and organic compounds to make energy (purple nonsulfur bacteria)

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9
Q

chemoautotroph

A

uses chemical sources and CO2 to make energy (iron-oxidizing bacteria)

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10
Q

chemoheterotroph

A

uses chemical sources and organic compounds to make energy (animals, fungi)

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11
Q

culture medium

A

nutrients prepared for microbial growth

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12
Q

sterile

A

no living microbes

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13
Q

inoculum

A

introduction of mircobes into the medium

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14
Q

culture

A

microbes growing in/on culture medium

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15
Q

chemically defined media

A

exact chemical compositions is known

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16
Q

complex media

A

extracts and digests of yeasts, meat, or plants (nutrient broth or agar)

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17
Q

culture media has all materials necessary for growth including…(4)

A
  • electron sources
  • energy sources (if not phototrophic)
  • carbon sources (if not autotrophic)
  • nitrogen sources (if no N2 fixer)
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18
Q

agar

A

used as a solidifying agent for culture media in Petri plates, slants, and deeps

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19
Q

agar is made of complex _____

A

polysaccharides

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20
Q

only one kind of bacteria can grow on MacConkey agar, which is it?

A

Gram-
(Gram+ inhibited by crystal violet and bile salts)

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21
Q

how do you obtain a pure culture?

A

through dilution streaking

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22
Q

dilution streaking

A
  • streak cells on a plate
  • agar inhibits spread of microbes on the plate
  • all cells in a colony derived from a single cell
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23
Q

a pure culture contains…

A

only one species or strain

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24
Q

a colony is a population of cells arising from…

A

a single cell or spore or from a group of attached cells

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25
a colony is also commonly called..?
a colony-forming unit (CFU)
26
dilution in liquid culture (2)
- reduces the number of cells in each tube - spread liquid on a plate to see single colonies
27
how to calculate bacterial growth-viable count
(number of colonies on plate) x (reciprocal of dilution sample = number of bacteria/ml EXAMPLE: (32 colonies on a plate) x (10,000 because the dilution was 1/10,000) = 320,000/ml in the sample
28
what is the Petroff-Hauser chamber?
it is a hemocytometer
29
hemocytometer
a counting-chamber device originally designed and usually used for counting blood cells
30
T/F: a hemocytometer can tell is a cell is alive or dead
FALSE: it cannot tell the difference and they must use stain to differentiate
31
spectrophotometer
measures optical density
32
T/F: A spectrophotometer can't tell if a cell is alive or dead
TRUE
33
flowcytometer
a technology that provides rapid multi-parametric analysis of single cells in solution
34
MPN or _____ _____ _____
most probable number
35
multiple tube MPN test
- count positive tubes - compare with a statistical table - used for very low counts
36
biofilms
cells acting together that secrete material to hold to a surface
37
quorum sensing
cells signal to each other
38
why are biofilms bad for antibiotics?
they prevent them from infiltrating
39
Given a log phase bacterial culture with 1x10^6 cells per ml and a generation time of 30 minutes, how long does it take the culture to reach a density of 6.4 x 10^7 cells/ml?
1 hour Work: (1x10^6)x = (6.4x10^7) x = (6.4x10^7)/(1x10^6) x = 64 = about 1 hour (I think)
40
Which of the following uses sunlight for energy and CO2 as a carbon source? - photoautotroph - chemoautotroph - photoheterotroph - chemoheterotroph
photoautotroph
41
What is the fastest way to measure cell density?
spectrophotometer
42
What shorted lag period would most likely be observed if a culture is transfered?
from a complex medium to a fresh complex medium
43
Any organism found in 'extreme' environments are called...?
extremophiles (extreme to humans)
44
environmental limits on microbial growth (5)
- temperature - pH - osmolarity - oxygen - pressure
45
microbes are commonly classified by their environmental niche: hyperthermophile
grow above 80ºC
46
microbes are commonly classified by their environmental niche: thermophile
grow between 50ºC and 80ºC
47
microbes are commonly classified by their environmental niche: mesophile
grow between 15ºC and 45ºC
48
microbes are commonly classified by their environmental niche: psychrophile
growth below 15ºC
49
microbes are commonly classified by their environmental niche: alkaliphile
growth above pH 9
50
microbes are commonly classified by their environmental niche: neutralophile
growth between pH 5 and 8
51
microbes are commonly classified by their environmental niche: acidophile
growth below pH 3
52
microbes are commonly classified by their environmental niche: halophile
growth in high salt contents
53
microbes are commonly classified by their environmental niche: aerobe
growth only in O2
54
microbes are commonly classified by their environmental niche: facultative
growth with or without O2
55
microbes are commonly classified by their environmental niche: microaerophile
growth only in small amounts of O2
56
microbes are commonly classified by their environmental niche: anaerobe
growth only without O2
57
microbes are commonly classified by their environmental niche: barophile
growth at high pressures greater than 380 atm
58
microbes are commonly classified by their environmental niche: barotolerant
growth between 10 and 495 atm
59
some 'extremophiles' are only know from...?
DNA sequences obtained from environmental samples
60
growth rate _____ with temperature
increases
61
what happens to proteins if temperatures are too high?
proteins denature
62
heat shock response
emergency proteins are produces to help keep proteins from denaturing
63
what kind of conditions trigger the heat shock response? (3)
- heat - high salt concentrations - arid conditions
64
temperature and food preservation
65
how are thermophiles adapted to high temperatures? (4)
- different amino acids and composition of proteins - proteins that stabilize DNA and prevent denaturation - more robust chaperone proteins to help fold proteins properly - more saturated in linear lipids in the membranes
66
microbes are commonly classified by their environmental niche: barosensitive
die at high pressure
67
why are barophiles difficult to study? (3)
- need a submarine or pressure chamber - they live at hydrothermal vents - deap-sea sites
68
cellular mechanisms in response to osmotic pressure: low
mechanosensitive channels relieve stress to release cell content
69

MCB 4403 (7 decks)

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