Yeast cells are to be separated from a fermentation broth. Assume that the cells are spherical with diameter 5 µm and density 1.06 g cm^-3. The viscosity of the culture broth is 1.36 x 10^-3 N s m^-2. At the temperature of separation, the density of the suspending fluid is 0.997 g cm^-3. 500 litres broth must be treated every hour. Specify Σ for a suitably-sized disc-stack centrifuge

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#Question id: 1126

#Section 3: Genetics, Cellular and Molecular Biology

Which of the following statement(s) is (are) true of the α subunit of a G protein?

a. It physically associates with the receptor.              

b. It binds GDP.

c. It binds GTP.                     

d. It is a transmembrane protein.

#Question id: 1127

#Section 3: Genetics, Cellular and Molecular Biology

Which of the following steps does not occur after acetylcholine binds to the muscarinic acetylcholine receptor in heart muscle cells?

#Question id: 1128

#Section 3: Genetics, Cellular and Molecular Biology

During the epinephrine stimulated conversion of glycogen to glucose 1-phosphate, which of the following steps involves protein phosphorylation?

a. inactivation of glycogen synthase               b. activation of protein kinase A

c. activation of adenylyl cyclise                      d. activation of glycogen phosphorylase

#Question id: 1129

#Section 3: Genetics, Cellular and Molecular Biology

Which of the following plays a role in the relaxation of smooth muscle cells by nitric oxide?

a. cGMP          b. protein kinase A      c. protein kinase G      d. guanylyl cyclise

#Question id: 1130

#Section 3: Genetics, Cellular and Molecular Biology

In muscle cells, glycogen phosphorylase kinase is activated by

a. Ca2+.           b. diacylglycerol.   c. nitric oxide.       d. protein kinase A.    

#Question id: 1133

#Section 3: Genetics, Cellular and Molecular Biology

What tertiary structure characterizes all cytokines?