Biochemical Miscellaneous
- A bacterial culture having a specific oxygen uptake rate of 5 mmol O2 (g-DCW)–1 hr–1 is being grown aerobically in a fed-batch bioreactor. The maximum value of the volumetric oxygen transfer coefficient is 0.18s–1 for the stirred tank bioreactor and the critical dissolved oxygen concentration is 20% of the saturation concentration (8mg/ml). The maximum density to which the cells can be grown in the fed-batch process without the growth being limited by oxygen transfer, is approximately.
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KLa = 0.185 S–1 = 5.139 × 10–5 hr–1
Critical dO2 is 20% of the saturate conc.(8 mg/ml)
Cell density. CL = 1.6 × 103.m/l C = (8 × 103 mg/l)
do2= KLa (C – CL)OUR = 1 / μ = qO2X 1 / O2
qO2 = mmo2/gm sw. hr.
= 5 × 10–3 gm dm hr
∴ KLa (C – CL) = q02X.⇒ X = KLa (C – CL) qO2 ∴ X = 5.139 × 10-5(8 - 1.6) × 103 = 65.779 g /lit. 5 × 10-3 Correct Option: D
KLa = 0.185 S–1 = 5.139 × 10–5 hr–1
Critical dO2 is 20% of the saturate conc.(8 mg/ml)
Cell density. CL = 1.6 × 103.m/l C = (8 × 103 mg/l)
do2= KLa (C – CL)OUR = 1 / μ = qO2X 1 / O2
qO2 = mmo2/gm sw. hr.
= 5 × 10–3 gm dm hr
∴ KLa (C – CL) = q02X.⇒ X = KLa (C – CL) qO2 ∴ X = 5.139 × 10-5(8 - 1.6) × 103 = 65.779 g /lit. 5 × 10-3
- The specific growth rate (µ) of a microorganism in death phase is
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Specific growth rate is defined as the increase in cell mass per unit time. In death phase, no cellular growth is observed. During this, the cell population continuously decreases with time and the population is said to have entered into death phase of the growth cycle. Therefore the value of specific growth constant for death phase is zero.
Correct Option: A
Specific growth rate is defined as the increase in cell mass per unit time. In death phase, no cellular growth is observed. During this, the cell population continuously decreases with time and the population is said to have entered into death phase of the growth cycle. Therefore the value of specific growth constant for death phase is zero.
- Main functions of baffles in a bioreactor are
P. to prevent a vortex
Q. to increase aeration
R. to reduce interfacial area of oxygen transfer S. to reduce aeration rate
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The main roles of a baffle in a bioreactor are
• Increase aeration rate
• to prevent a vortexCorrect Option: A
The main roles of a baffle in a bioreactor are
• Increase aeration rate
• to prevent a vortex
- How many kilograms of ethanol is produced from 1 kilogram of glucose in ethanol fermentation?
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C6H12O6 + Zymase → 2 C2H5OH + 2 CO2 use mass balance process to calculate the ethanol production.
180g of Glucose yields = 92 g of ethanol
Therefore, 1000g of glucose yields = 92 / 180 * 1000 = 0.51 kg Correct Option: C
C6H12O6 + Zymase → 2 C2H5OH + 2 CO2 use mass balance process to calculate the ethanol production.
180g of Glucose yields = 92 g of ethanol
Therefore, 1000g of glucose yields = 92 / 180 * 1000 = 0.51 kg
- Downstream processing of an industrial process yielded a highly purified bioactive protein. This protein was subjected to cleavage by trypsin. Chromatographic separation of products resulted in 4 peptides (P, Q, R, S) with the following amino acid sequences
P. phe-val-met-val-arg
Q. ala-ala-try-gly-lys
R. val-phe-met-ala-gly-lys
S. phe-gly-try-ser-thr
Chemical cleavage of the same protein with cyanogenbromide and chromatographic separation resulted in three peptides (i, ii, iii) with the following sequences
(i) ala-gly-lys-phe-gly-try-ser-thr
(ii) ala-ala-pry-gly-lys-phe-val-met
(iii) val-arg-val-phe-met
The order of the peptides that gives the primary structure of the original protein is
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Cyanogen bromide hydrolyzes peptide bonds at the C-terminus of methionine residues. This reaction is used to reduce the size of polypeptide segments for identification and sequencing. The aspartate residue (Asp 189) located in the catalytic pocket (S1) of trypsins is responsible for attracting and stabilizing positively charged lysine and/or arginine, and is, thus, responsible for the specificity of the enzyme. This means that trypsin predominantly cleaves proteins at of the amino acids lysine and arginine except when either is bound to a N-terminal proline. Although large-scale mass spectrometry data suggest cleavage occurs even with proline. Trypsins are considered endopeptidases, i.e., the cleavage occurs within the polypeptide chain rather than at the terminal amino acids located at the ends of polypeptides.
Correct Option: C
Cyanogen bromide hydrolyzes peptide bonds at the C-terminus of methionine residues. This reaction is used to reduce the size of polypeptide segments for identification and sequencing. The aspartate residue (Asp 189) located in the catalytic pocket (S1) of trypsins is responsible for attracting and stabilizing positively charged lysine and/or arginine, and is, thus, responsible for the specificity of the enzyme. This means that trypsin predominantly cleaves proteins at of the amino acids lysine and arginine except when either is bound to a N-terminal proline. Although large-scale mass spectrometry data suggest cleavage occurs even with proline. Trypsins are considered endopeptidases, i.e., the cleavage occurs within the polypeptide chain rather than at the terminal amino acids located at the ends of polypeptides.
