Stoichometry of cell growth and product formation Flashcards
What’s a frequently used term for cells in cell growth?
Biomass
What law does cell growth obey?
Law of conservation of matter
Write the general equation for aerobic cell growth.
What can be used as a general formula for biomass if compositional analysis is not available?
Figure showing aerobic cell growth process
What are the balance equations for finding stoichiometric equations?
How is the relationship between the amount of biomass produced and the amount of substrate consumed quantitatively expressed?
Biomass yield
Biomass yield can be used to find which stoichiometric coefficient in the general equation for aerobic cell growth?
c
In many fermentations, extracellular products are also formed during growth in addition to biomass. When this occurs, the stoichiometric equation can be modified to reflect product synthesis. Give the general formula for the extracellular product and equation
CjHkOlNm
Product synthesis introduces one extra unknown stoichiometric coefficient to the equation;
thus, an additional relationship between the reactants and products is required.
This is usually provided as another experimentally determined yield coefficient, the product yield from the substrate, give the equation for this.
What else can be useful in evaluating stoichiometric coefficients?
Additional relationships based on electron balances and degree of reduction
What do available electrons refer to?
number of electrons available for transfer to oxygen on combustion of a substance to CO2, H2O, and nitrogen-containing compounds.
The number of available electrons found in organic material is calculated from the valence of the
various elements: 4 for C, 1 for H, -2 for O, 5 for P, and 6 for S and -3 for N with ammonia as a
reference.
What is degree of reduction?
Defined as the number of equivalents of available electrons in that
quantity of material containing 1 g atom of carbon
For substrate CwHxOyNz
calculate the number of available electrons.
4w + x - 2y - 3z
