Nicotiana tabacum cells are cultured to high density for production of polysaccharide gum. The reactor used is a stirred tank, containing initially 100 litres medium. The maximum specific growth rate of the culture is 0.18 d^-1 and the yield of biomass from substrate is 0.5 g g^-l. The concentration of growth-limiting substrate in the medium is 3% (w/v). The reactor is inoculated with 1.5 g l^{- 1} cells and operated in batch until the substrate is virtually exhausted; medium flow is then started at a rate of 4 l d^-1. Fed-batch operation occurs under quasi-steady-state conditions. Estimate final biomass concentration?

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#Question id: 4304

#Section 3: Genetics, Cellular and Molecular Biology

Using codon table, identify a 5′ → 3′ sequence of nucleotides in the DNA template strand for an mRNA coding for the polypeptide sequence Phe-Pro-Lys.

TLS Online TPP Program

#Question id: 4305

#Section 3: Genetics, Cellular and Molecular Biology

Which of the following molecules is a protein produced by a regulatory gene?

TLS Online TPP Program

#Question id: 4306

#Section 3: Genetics, Cellular and Molecular Biology

Which of the following molecules helps to "turn off" genes in a cell?

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#Question id: 4307

#Section 3: Genetics, Cellular and Molecular Biology

When taken up by a cell, which of the following molecules binds to a repressor so that the repressor no longer binds to the operator?

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#Question id: 4308

#Section 3: Genetics, Cellular and Molecular Biology

Most repressor proteins are allosteric. Which of the following molecules binds with the repressor to alter its conformation and therefore affect its function?

TLS Online TPP Program

#Question id: 4309

#Section 3: Genetics, Cellular and Molecular Biology

Imagine that you've isolated a yeast mutant that contains histones resistant to acetylation. What phenotype would you predict for this mutant?