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Biochemical Engineering > Cell Growth > Flashcards

Cell Growth Flashcards

(90 cards)

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1
Q

________ is autocatalytic

A

Growth

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2
Q

Characterized by specific growth rate, μ

A

Cell Growth

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3
Q

Cell Growth

A

cells + substrate → extracellular products + new cells + original cells

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4
Q

Cell concentration can be measured directly and/or indirectly.

A

Measuring Cell Concentration

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5
Q

__________: mass or cell number basis.

A

Direct

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6
Q

Cell number counting: ______________

A

hemocytometer, plate counts and particle counts

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7
Q

Advantage: accurate, typically low noise in measurement.

A

Counting Cells: Hemocytometer.

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8
Q

Disadvantage: time consuming, carcinogenic, mutagenic stains.

A

Counting Cells: Hemocytometer.

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9
Q

petri dish or dilution plate counts: count colonies formed by individual cells (dilute sample)

A

Counting Cells: Plate Counts

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10
Q

CFUs = ___________

A

colony forming units

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11
Q

Advantages: counts viable cells, fairly accurate.

A

Counting Cells: Plate Counts

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12
Q

Disadvantages: noisy, takes days.

A

Counting Cells: Plate Counts

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13
Q

Particle counters (Coulter counter): measure particle size distributions.

A

Counting Cells: Particle Counters

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14
Q

Advantages: very quick, obtain a size distribution in addition to a count.

A

Counting Cells: Particle Counters

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15
Q

Disadvantages: solutions must be particle free for accurate count, hardware, expensive, complicated.

A

Counting Cells: Particle Counters

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16
Q

Most common units to report biomass.

A

Mass Concentration

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17
Q

Obtained by centrifuging sample, drying and weighing.

A

Mass Concentration

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18
Q

Advantages: concentration Mass is typical variable in models, simple, low-tech method.

A

Mass Concentration

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19
Q

Disadvantages: Presence of solids makes inaccurate, difficult to measure low biomass concentrations.

A

Mass Concentration

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20
Q

Turbidimeter or spectrophotometer (most common).

A

Indirect Concentration Measurements

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21
Q

Substrate uptake or product evolution.

A

Indirect Concentration Measurements

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22
Q

Luciferin/ATP fluorescence

A

Indirect Concentration Measurements

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23
Q

Protein or DNA/RNA concentration measurements.

A

Indirect Concentration Measurements

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24
Q

Is a measure of the amount of light that passes through a turbid sample.

A

Optical density

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25
Reported with the wavelength of the light used in the measurement. For example OD600 = optical density at 600 nm.
Optical density
26
________ is often measured in OD and converted to mass per volume with a standard curve.
Biomass
27
Fixed amount of substrate (growth medium) present at beginning.
Batch Cultures
28
_______ is seeded with an inoculum (small amount of live cells to start growth).
Batch
29
5 phases of growth:___________
lag, exponential, deceleration, stationary, death.
30
Adaptation as inoculum cells adjust enzyme systems to new environments (repression of unneeded systems, induction of useful enzyme systems).
Lag Phase
31
Growth is suppressed, duration 1-10 hours
Lag Phase
32
Extended by low temperature, small inoculum, radical substrate/temperature changes, low nutrient levels, inoculum "age".
Lag Phase
33
Inoculum should be 5 volumes % and from exponential phase culture.
Lag Phase
34
___________ can exist with multiple growth substrates (diauxic growth).
Multiple lag phases
35
Growth is balanced (intracellular concentrations remain constant).
Exponential Growth Phase
36
No dependence on substrate concentration (growing at intrinsic maximum growth rate).
Exponential Growth Phase
37
Primary metabolites (growth associated) produced.
Exponential Growth Phase
38
Growth rate is 1st order with respect to cell concentration, Oth order with respect to substrate concentration.
Exponential Growth Phase
39
End of exponential phase.
Deceleration Phase
40
Caused by either build-up of toxic products or depletion of substrate.
Deceleration Phase
41
Cell physiology changes to favor survival overgrowth.
Deceleration Phase
42
Net growth rate is zero.
Stationary phase
43
Cells produce secondary metabolites (not growth associated).
Stationary phase
44
Many products important to the biotechnology industry are produced during this phase.
Stationary phase
45
Cells begin to lose ability to reproduce.
Stationary phase
46
Cells begin to lyse, cryptic growth occurs.
Stationary phase
47
Cells catabolize energy reserves (eg; PHB) in endogenous metabolism
Stationary phase
48
Although growth slows or ceases, maintenance requirements still exist.
Stationary phase
49
Death is relative to the population, death always occurs.
Death Phase
50
Commonly modeled as a 1st order process with respect to biomass.
Death Phase
51
Some portion of cells remain viable for a long time, but are altered
Death Phase
52
Growth yield microorganisms = produced per unit substrate utilized
Growth Yield, Yield Coefficient
53
_______________ is similarly affected relative to diffusion.
Biological reaction rate
54
pH optima: _______________
bacteria 3-8, yeast 3-6 molds 3-7 plant cells 5-6, animal cells 6.5-7.5
55
pH varies significantly during fermentation if system is not buffered or controlled for pH.
Effects of pH
56
CO2 evolution and ammonium as nitrogen source both lower pH.
Effects of pH
57
Nitrate utilization raises pH.
Effects of pH
58
________ can become a limiting substrate.
DO
59
At________ concentration, growth is independent of [O2].
high DO
60
O₂ solubility in water ~____________
7 ppm (25°C, 1atm)
61
Bacteria require ~___________
10% of saturation for [O2] independent growth, yeast 10-50%.
62
_____________ is usually limited by stagnant liquid around bubbles.
Rate of O₂ transfer
63
When O₂ transfer is limiting ____________ , so ….
OTR=OUR
64
Very high maybe toxic to some organisms
Dissolved Carbon Dioxide
65
Cells require certain DCO2 for proper metabolic functions
Dissolved Carbon Dioxide
66
Controlled by changing CO2 conc. In air supply and agitation speed Ionic Strength
Dissolved Carbon Dioxide
67
Affect the transport of certain nutrients in and out of the cell
Dissolved Carbon Dioxide
68
Metabolic functions of cells
Dissolved Carbon Dioxide
69
Solubility of certain nutrients
Dissolved Carbon Dioxide
70
Structured versus unstructured (cell composition does not change with time).
Models for Growth Kinetics
71
Segregated versus unsegregated (all cells are identical).
Models for Growth Kinetics
72
_________ is an unstructured, unsegregated model.
Monod equation
73
Single substrate controls growth. (low population density)
Monod equation
74
Analogous to Michaelis-Menten enzyme kinetics and the Langmuir isotherm.
Monod equation
75
Mechanistic if one enzyme system controlled growth
Monod equation
76
Maintenance: _________________
energy expenditures for repair, transport, motility
77
Endogenous metabolism: ____________
consumption of storage polymers for energy
78
There are other nonsegregated, unstructured models for cell growth but the difference is not worth the work.
Other Models for Cell Growth
79
___________ are not typically mechanistic, but are selected to fit data.
Inhibitory kinetic expressions
80
__________ are analogous to inhibited enzyme kinetics.
Expressions
81
If a substrate is inhibiting cell growth of a batch culture, the substrate should be added in a fed- batch mode.
Growth Inhibition by Substrate
82
Inhibitory kinetic expressions are not typically mechanistic, but are selected to fit data.
Growth Inhibition by Product
83
If a product inhibits cell growth of a batch culture, the product recovery will be expensive.
Growth Inhibition by Other Compounds
84
Instrumentation
pH probe and controller DO probe and controller Antifoam probe and controller Level probe and controller Nutrient addition pump Agitation rate controller
85
Shuler uses ____ to represent changes in cell mass due to endogenous respiration and ka' for changes in cell mass due to cell death and lysis.
Kd
86
__________: catabolism of cellular reserves for continued maintenance and energy.
Endogenous respiration
87
WWWebster's Dictionary: 2.b) the quantitative relationship between two or more substances especially in processes involving physical or chemical change
Stoichiometry
88
If cells have a characteristic molecular composition (i.e.; CH₂ON) then yield coefficients can be determined through stoichiometry. In practice, these estimates.
Stoichiometry
89
The system is determinate and we can form the yield coefficients
Yield Coefficients
90
from the stoichiometric coefficients and formula weights.
Yield Coefficients

Biochemical Engineering (7 decks)

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