During exponential phase in batch culture, the growth rate of a culture is proportional to the concentration of cells present. When Streptococcus lactis bacteria are cultured in milk, the concentration of cells doubles in45 min. If this rate of growth is maintained for 12 h, what is the final concentration of cells relative to the inoculum level?

#Question id: 1133

#Section 3: Genetics, Cellular and Molecular Biology

What tertiary structure characterizes all cytokines?

#Question id: 1134

#Section 3: Genetics, Cellular and Molecular Biology

Arrange the following proteins in the proper order in which they become activated in the MAPK signaling pathway:

a. MAP kinase                         b. MEK           c. Ras              d. Raf              e. RTK            

#Question id: 1136

#Section 3: Genetics, Cellular and Molecular Biology

Which of the following signaling pathways can be activated by activation of receptor tyrosine kinases?

a. phospholipase Cγ                b. PI-3 kinase

c. MAP kinase                         d. none of the above

#Question id: 1137

#Section 3: Genetics, Cellular and Molecular Biology

A loss-of-function mutation in PTEN phosphatase results in

a. increased cell proliferation.            

b. decreased cell proliferation.

c. increased apoptosis.                                   

d. decreased apoptosis.

#Question id: 1138

#Section 3: Genetics, Cellular and Molecular Biology

A loss-of-function mutation in Wnt would have a phenotype similar to a

a. gain-of-function mutation in GSK-3.                    

b. gain-of-function mutation in β-catenin.

c. loss-of-function mutation in GSK-3.                     

d. loss-of-function mutation in β-catenin.

#Question id: 1140

#Section 3: Genetics, Cellular and Molecular Biology

Cell sensitivity to an external signal is determined by: