Lactobacillus casei is propagated under essentially anaerobic conditions to provide a starter culture for manufacture of Swiss cheese. The culture produces lactic acid as a by-product of energy metabolism. The system has the following characteristics:

                                                                 

 

A stirred fermenter is operated in fed-batch mode at quasisteady state with a feed flow rate of 4 m³ h^-1 and feed substrate concentration of 80 kg m^-3. After 6 h, the liquid volume is 40 m³. What mass of cells is produced after 6 h fed-batch operation?

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#Question id: 3750

#Section 3: Genetics, Cellular and Molecular Biology

Which of the following facts did Hershey and Chase make use of in trying to determine whether DNA or protein is the genetic material?

#Question id: 3752

#Section 3: Genetics, Cellular and Molecular Biology

Which of the following investigators was (were) responsible for the discovery that in DNA from any species, the amount of adenine equals the amount of thymine, and the amount of guanine equals the amount of cytosine?

#Question id: 3753

#Section 3: Genetics, Cellular and Molecular Biology

Cytosine makes up 42% of the nucleotides in a sample of DNA from an organism. Approximately what percentage of the nucleotides in this sample will be thymine?

#Question id: 3754

#Section 3: Genetics, Cellular and Molecular Biology

Thymine makes up 28% of the nucleotides in a sample of DNA from an organism. Approximately what percentage of the nucleotides in this sample will be guanine?

#Question id: 3755

#Section 3: Genetics, Cellular and Molecular Biology

In E. coli, there is a mutation in a gene called dnaB that alters the helicase that normally acts at the origin of replication. Which of the following events would you expect to occur as a result of this mutation?

#Question id: 3756

#Section 3: Genetics, Cellular and Molecular Biology

 In E. coli, which enzyme catalyzes the elongation of a new DNA strand in the 5' → 3' direction?