BIS 104 PQs 10, 11

# BIS 104 PQs 10, 11 - BIS 104 PQs 10, 11 10. ...

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Unformatted text preview: BIS 104 PQs 10, 11 10. After many fractionation steps you have partially purified an antibody (IgG) from the whole blood of an immunized rabbit. The fraction you have obtained has a protein concentration of 500 ug/ml and consists of approximately 99% IgG and 1% of a contaminating protein, “X”. The pI of this IgG is 6.5 and the pI of “X” is 7.5. To further analyze your fraction, you run a 10 ul sample on SDS ­PAGE under non ­reducing conditions at pH 7.5. When you stain the resulting gel with Coomassie Blue (CB). You see two bands. One band has a relative mobility (Rm) of 0.35, corresponding to a mol wt of ~150kDA. The other band has a Rm of 0.80. a. How did you determine the Rm values? b. Which of the two bands represents the IgG? c. Would the intensity of CB staining be the same or different for the two bands? Explain. d. If you saw only one CB band on the gel, what would be one possible explanation for this? e. How would the CB banding pattern change if the SDS ­PAGE were run under reducing conditions? 11. Suppose that a post ­mitotic cell grows such that its diameter increases from 15 um to 30 um. Calculate and compare the before and after cell surface (plasma membrane) to cell volume ratio for the two cells. For the purpose of this calculation, assume that the cells are in the form of perfect spheres. a. Does the area to volume ratio increase or decrease with growth of the cell? b. What role might this change play in determining the size of cells? ...
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