Cell Metabolism - Bioprocess Engineering: Kinetics, Biosystems, Sustainability and Reactor Design - page 547

and (10.18) , as a function of the inducer concentration [S L ] T . Comment on the
results.
10.4. Derive rate expressions for the productions of P 1 and P 2 and consumption of M 1 for
concerted feedback control of branched pathways as shown in Fig. 10.15 b. Assume
that PSSH applies. Discuss what happens if the concentrations of P 1 and/or P 2 are
high in the medium. Clearly define the symbols you use.
10.5. Derive flux expressions for the productions of P 1 and P 2 and consumption of M 1 for
cumulative feedback control of branched pathways as shown in Fig. 10.15 d. Assume
that PSSH applies. Discuss what happens if the concentrations of P 1 and/or P 2 are
high in the medium. If experimental data were collected for the variation of
concentrations of M 1 ,P 1 , and P 2 with time, what rate expression(s) you would
recommend to use to analyze the experimental data? Clearly define the symbols you
use.
10.6. How many ribosomes are actively synthesizing proteins at any instant in an E. coli cell
growing with a 45-min doubling time? The birth size of E. coli is 1 m m in diameter and
2 m m in length. The water content is 75%. About 60% of the dry material is protein, and
the rate of amino acid addition per ribosome is 20 amino acids per second. The average
molecular weight of free amino acids in E. coli is 126.
10.7. Describe simple experiments to determine if the uptake of a nutrient is by passive
diffusion, facilitated diffusion, active transport, or group translocation.
10.8. Consider the transport of glucose into cells in a medium containing 1 g/L glucose. The
maximum glucose uptake flux is J Smax a

2gl 1 h 1 , K SE ¼ ¼ 2 mg/L, K SI ¼ 0.5 g/L.

Determine
(a) Maximum biotic glucose concentration. Does this concentration make sense?
(b) The concentration of glucose in the biotic fluid if glucose consumption rate is

$ h 1 .
10.9. Consider the transport of xylose into cells in a medium containing 10 g/L xylose. The
maximum xyose uptake flux is J Smax a

0.8 g $ L 1 r S ¼

1.8 g l 1 h 1 , K SE ¼

¼

2.5 mg/L, K SI ¼ 0.25 g/L.

Determine
(a) Maximum biotic xylose concentration. Does this concentration make sense?
(b) The biotic xylose concentration if xyose consumption rate is 0.5 g L 1 h 1 .

10.10. For the m-RNA nucleotide code below: a) Deduce the corresponding sequence of
amino acids. b) What is the corresponding nucleotide sequence on the chromosome?
This sequence codes for a part of insulin.

r S ¼

CCG UAU CGA CUU GUA ACA ACG CGC

10.11. Identify the enzymes needed in the TCA cycle as shown in Fig. 10.22 .
10.12. Identify the enzymes needed in the glyoxylate cycle as shown in Fig. 10.24 .
10.13. Explain the difference between feedback inhibition and feedback repression.
10.14. You are asked by your boss to produce a human protein in E. coli. Because you have
learned some of the differences in the way that prokaryotes and eukaryotes make
proteins, you worry about at least two factors that could complicate production of an
authentic protein for human use.