Cell Growth pt. 3 Flashcards
These intermediates are replaced by anaplerotic reactions
Replenishing intermediates
Cells can also fix ________ to replace _______ (_________ carbon dioxide fixation)
- carbon dioxide
- intermediates
- heterotrophic
TCA cycle intermediates can be ________ for biosynthesis
funneled off
Anaerobic respiration can occur by using ____ as a terminal electron acceptor in the ETC.
nitrate
Many cells can also generate energy without the _____, but with a ________.
- ETC (electron transport chain)
- lower efficiency
In _____________, no net oxidation or reduction since electron transport chain is not available to produce NAD+ required in TCA cycle.
Alcohol and Lactate Formation
Pentose phosphate pathway generates ______ (reducing power for biosynthesis) and __________ (make up ATP, RNA, DNA, others).
NADPH
5 carbon sugars
Cell growth is characterized by?
specific growth rate, μ
Cells + _____ –> ______ + new cells + _______
- substrate
- extracellular products
- original cells
can be measured directly and/or indirectly.
Cell concentration
Measuring cell concentration: mass or cell number basis
Direct
Cell number counting: (3)
- hemocytometer
- plate counts
- particle counters
Type of Counting Cells
Advantage: accurate, typically low noise in measurement
Disadvantage: time consuming, carcinogenic, mutagenic stains
Hemocytometer
Type of Counting Cells
Advantage: counts viable cells, fairly accurate
Disadvantage: noisy, takes days.
- Plate counts
Type of Counting Cells
Advantages: very quick, obtain a size distribution in addition to a count.
Disadvantages: solutions must be particle free for accurate count, finicky, hardware, expensive, complicated.
Particle Counters
count colonies (CFUs = colony forming units) formed by individual cells (dilute sample).
petri dish or dilution plate counts
Most common units to report biomass
Mass concentration
Mass concentration can be obtained by _________, _________, and ____________.
centrifuging sample, drying and weighing
_________________
Advantages: typical variable in models, simple, low tech method.
Disadvantages: Presence of solids makes inaccurate, difficult to measure low biomass concentrations.
Mass concentration
Indirect Concentration Measurements
- _____________ (most common).
- ____________ uptake or product evolution.
- ____________/ATP fluorescence.
- Protein or _______________ concentration measurements.
- Turbidometer or spectrophotometer
- Substrate
- Luciferin
- DNA/RNA
the measure of the amount of light that passes through a turbid sample
Optical density
_____ is often measured in OD and converted to mass per volume with a standard curve
Biomass
_______
- Fixed amount of ____________ (growth medium) present at beginning.
- Batch is seeded with an _________ (small amount of live cells to start growth).
- Batch Cultures
- substrate
- inoculum
5 Phases of Growth
- Lag
- Exponential
- Deceleration
- Stationary
- Death
_________
- Growth is suppressed, duration 1-10 hours. .
- Inoculum should be _________and from exponential phase culture.
- Multiple ____ can exist with multiple growth substrates (diauxic growth)
- Lag Phase
- 5 volume %
- lag phases
___________
- Growth is balanced (intercellular concentrations remain constant)
- __________ on substrate concentration (growing at intrinsic maximum growth rate).
- Growth rate is __________ with respect to cell concentration, 0th order with respect to substrate
concentration.
- Exponential Growth Phase
- No dependence
- 1st order ,
Changes depending on the types of kinetics.
Doubling Times
_____________
- End of exponential phase.
- Caused by either build-up of toxic products or ______________of substrate.
- Cell _______ changes to favor survival over growth.
- Deceleration Phase
- depletion
- physiology
_______________
- Net growth rate is zero.
- Cells produce _______ metabolites (not growth associated).
- Cells begin to lose ability to ______.
- Cells begin to lyse, ________ growth occurs.
- Cells ________ energy reserves (eg; PHB) in endogenous metabolism
- Stationary Phase
- secondary
- reproduce
- cryptic
- catabolize
________
- is relative to the population, always occurs.
- Commonly modeled as a ____ process with respect to biomass.
- Some portion of cells remain _______ for a long time, but are altered.
- Death Phase
- 1st order
- viable
microorganisms produced per unit substrate utilized.
Growth yield
This rate is similarly affected relative to diffusion.
Biological reaction rate
Effects of pH
pH optima:
1. bacteria ,
2.. yeast ,
1. molds ,
1. plant cells ,
1. animal cells .
- 3-8,
- 3-6
- 3-7
- 5-6
- 6.5-7.5
Effects of pH
- pH varies significantly during fermentation if system is not _______ or controlled for pH.
- CO2 evolution and ______ as nitrogen source both lower pH.
- ____ utilization raises pH.
- buffered
- ammonium
- Nitrate
____ can become limiting substrate.
Dissolved Oxygen
At high DO concentration, growth is _______of [02].
independent
Dissolved Oxygen Requirements
- O₂ solubility in water ~7 ppm (25°C, 1atm).
- Bacteria require ____ of saturation for [02] independent growth, yeast ___.
- Rate of O₂ transfer usually limited by _______ around bubbles
- ~10% , 10-50%
- stagnant liquid
CFU
Colony Forming Units
