Lecture 7 - Stoichiometry

Question 1

Sketch stoichiometric growth from energy source and carbon source

Answer 1

slide 2

Question 2

Sketch the stoichiometry of a cell and write the general equation of substrate and biomass

Answer 2

slide 7

Question 3

What is a cell cycle
How does the composition of a cell chenge
Why can we define average cell composition

Answer 3

The various events that occur during the growth of a single cell from inception to division are referred to as the cell cycle

The biochemical composition of the cell is constantly changing during the cell cycle

cells are usually distributed over all points in the cell cycle, we can define an average cell composition based on all cells in the population

Question 4

Draw a generic equation for substrate and biomass and provide stoichiometric values for C, H, O and N balance

Answer 4

Slide 12

Question 5

What is a useful principle of electron balancing and what can it be used for

Answer 5

Conservation of reducing power, or available electrons

Used to determine quantitative relationships between substrate and products

Question 6

What does available electrons mean

Answer 6

It is the number of electrons available to transfer to O2 on combustion to CO2, H2O and Nitrogen contatining compounds

Question 7

What is the valence for C, H, O, P, and S

Answer 7

4
1
-2
5
6

Question 8

What is an exception for the valence of N when it is not -3

Answer 8

N2 = 0
NO2- = 5

Question 9

What is the degree of reduction

Answer 9

The number of available electrons per mole of carbon

Question 10

What is the number of available electrons on
CwHxOyNz
What is the degree of reduction?

Answer 10

4w+1x-2y-3z

(4w+1x-2y-3z)/w

Question 11

Define Yp/s

Answer 11

g product formed/g substrate used

Question 12

write an electron balance and re-arange for an equation which can be used to calculate the theoretical oxygen demand

Answer 12

wys - 4a = cyb +fjyp

a = 1/4 x (wys - cyb - fjyp)

Question 13

Using the equation for theoretical oxygen demand derive a new one which fractionates the available electrons from substrate to oxygen, biomass, and product

Answer 13

1 = (4a/wys) + (cyb/wys) + (fjyp/wys)

Question 14

Define cmax

Answer 14

If there was no other product and all available electrons are used for biomass formation (zetab) = 1

Similar for product

Question 15

How can cmax be used in biomass yield

Answer 15

Yx/s = g cells produced/g substrate used

Yx/s = c(MW cells)/(MW substrate)