A two-stage chemostat system is used for production of secondary metabolite. The volume of each reactor is 0.5 m³; the flow rate of feed is 50 l h^{- 1}. Mycelial growth occurs in the first reactor; the second reactor is used for product synthesis. The concentration of substrate in the feed is 10 gl^-1. Kinetic and yield parameters for the organism are:

                                                            

Assume that product synthesis is negligible in the first reactor and growth is negligible in the second reactor. Determine cell concentrations entering the second reactor.

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#Question id: 634

#Section 2: General Biology

An enzyme has a Vmax of 50 micromol product formed (minute x mg protein)-1 and a Km of 10 microM for the substrate. When a reaction mixture contains the enzyme and 5 microM substrate, which of the following percentages of the maximum velocity will be closest to the initial reaction rate?

#Question id: 635

#Section 2: General Biology

The enymatic rate constant (kcat/Km) of orotidine 5ʹ-phosphate decarboxylase is 6 x 10⁷ M^-1s^-1 and the nonenzymatic rate constant (kn) is 3 x 10^-16 s^-1.  What is the value of the enzymeʹs catalytic proficiency?

#Question id: 636

#Section 2: General Biology

DNA polymerase contains a lysine residue that is important for binding to DNA. Mutations were found that converted this lysine to either glutamate, glycine, valine, or arginine. Which mutations would be predicted to be the most and least harmful to the ability of the enzyme to bind DNA?

#Question id: 638

#Section 2: General Biology

Match the following class of enzymes with them

#Question id: 639

#Section 2: General Biology

Match the coenzymes in column I enzymes to class of enzymes in column II

#Question id: 640

#Section 2: General Biology

The data in the table above were collected for an enzyme-catalyzed reaction. The Km for this enzyme is approximately