PART 1 - Kinetics of Substrate Utilization, Product Formation and Biomass Production in Cell Cultures Flashcards
Batch Growth, CSTR or Chemostat, Balanced Growth
___________ are apparatus or structures in which a chemical, biological and/or
physical process are facilitated
Reactors
____________ are model systems for which the transport processes
and chemical reactions are exactly defined.
Ideal reactors
For a reactor to be ideal, it must be:
- controlled
- analog and prototype
- mathematically modeled
Types of ideal reactors in the context of enzymatic and culture processes:
- Batch operation of mixed enzyme reactor
- Continuous operation of mixed enzyme reactor
Batch process is an ____________________ operation where the __________,_________ changes with ______.
unsteady state
concentration of cell mass, substrate changes with TIME
Batch processes operate in ________________
closed systems
Explain what happens in batch processes
substrate is added at the beginning of the process and products removed only at the end.
What are classified as batch
Bioreactors with neither input nor output of liquid
or solid material
In Batch, the mass of substrate in the reactor, M, is equal to the ________________ multiplied by the ________________.
substrate concentration s
liquid volume V
Recite the initial equation of Batch Time from Mass Balance for Enzymatic Reaction
d(sV)/dt = -(VmaxS/Km+S)V
Since V is constant,
Take V outside the differential, and cancel from both sides
Enzymes are subject to _______________. Accordingly, the concentration of active enzyme in
the reactor, and therefore the value of __________, may change during reaction.
deactivation, vmax
Microorganisms have specific ___________ and _____ ranges at which they thrive
temperature, pH
Cell growth process got two different manifestations according to the morphology of cell
involved: EXPLAIN UNI ORGANISMS AND MOLDS
For unicellular organisms which divide as they grow, increases in biomass are accompanied by increases in the number of cells present.
Unlike unicellular organisms, molds do not necessarily undergo cell division as the primary means of growth. Instead, they grow by
elongation and branching of their filamentous structures.
Certain parameters/ phenomena to
consider in determining the cell population kinetics
What does it do to formulate a simple kinetic model for cellular activities
- characteristics of culture broth,
- nutrients and substrates used for growth and production of metabolites
- cell to cell heterogeneity
- microbial cells of different ages manifesting metabolic activities
- characterization of biochemical pathway
THEY ARE COMPLEX
They make it difficult to formulate a simple kinetic model
Two processes are associated with cell growth
- utilization of materials from the medium
by the cells - generation of metabolic end products in the medium
Define the RATE-LIMITING SUBSTRATE
First, it is assumed that
the concentration of all components present in the medium is sufficiently high and the rate of
reaction depends on the concentration of that component only.
The process by which cells generate energy, involves various metabolic pathways.
Cellular respiration
These are used to maintain optimal growth conditions
Incubators, Bioreactors, and Temperature-Controlled Environments
What can be indicative of alterations in cell structure,
function, or health
Changes in the
rheological properties of cells, including viscosity,
This refers to the study of the flow and deformation of matter, and it plays a role in understanding the mechanical properties of cells
Rheology
This may contribute to the diversity observed in different phases of cellular activities.
Stochastic events
This can contribute to genetic variability among cells within a population
Genetic drift, as
a random process
They classified the microbial systems according to the number of components used in the
cellular representation.
Arnold Fredrickson and Henry
Tsuchiya
Model classifications for mathematical representation of cell populations: ENUMERATE AND EXPLAIN EACH
This is one perspective in which microbial cells are considered as
multicomponent systems. These models are very complex and not used very often.
Structured model
One common type of structured model in cell growth is the
age-structured model
The structured model usually deals with the kinetics of the change in individual components present in the cells, such as
RNA, DNA, proteins, etc
When cell population is treated as one component system, it is referred to as
Unstructured
model
Model assumes balanced growth where cell components do not change with time. Much less complex and much more commonly used.
Unstructured Model
This consider individual cells, in recognition of the fact that cells in a
population – a pure culture – are different and are most often formulated as a population balance
model.
Segregated Model
These models form an important class and describe the biomass as
consisting of several variables (such as NADH, precursors, metabolites, ATP, biomass).
Unsegregated structured models
The real condition of the living system is
a structured, segregated one
In ideal conditions,
the cell growth kinetics is assumed to be in the
unsegregated, unstructured mode
This is typically prepared by using a seed culture in a liquid medium.
Inoculum
It is the period where the individual bacteria are maturing and not yet able to divide.
Lag phase
The log phase is sometimes called
the logarithmic phase or the exponential phase.
