4. Electrophoresis is sometimes used in clinical labs to detect major abnormalit

Question

4. Electrophoresis is sometimes used in clinical labs to detect major abnormalities in a patient's blood proteins. To make the photo shown here, serum (the fluid of blood minus the cells) was applied to the sample well (marked with an asterisk), then the current was turned on. After the current was shut off, the gel was soaked in a solution of dyc in order to stain the proteins. The charges of the electrodes are indicated. immunoglobulins (a) (0.5 point) What can you conclude about the net charge of albumin compared to the net charge of immunoglobulins (antibodies)? Explain your reasoning. (b) (1 point) If you view this page in color, you can see that the protein "bands" are stained bluc. You used this blue dye in a previous lab for this course. What is the blue dye? How do you know that it will bind to proteins such as albumin? (c) (0.5 point) Assuming that the blue dye binds with equal affinity to all types of proteins, what protein appears to have the highest concentration in human serum? (d) (0.5 point) If the serum sample above contained some DNA, approximately where would the DNA "band" appear (assuming that you had a way to stain the DNA)? Explain your reasoning (e) (0.5 point) What appears to be wrong with the patient whose serum produced the electrophoresis results shown here? 5. 1 point) Ribosomes contain four sample well types of RNA molecules, called 18S (1874 nucleotides), 28S (4718 nucleotides), 5.S (120 nucleotides), and 5.8S (180 nucleotides). Electrophoresis of ribosomal RNA gave the results shown here. Add a plus and minus sign to indicate the positions of the electrodes and identify the type of RNA in each band.

Explanation / Answer

4.

(a) Net charge on albumin is negative while net charge on immunoglobulin is positive since they move towards positive and negative electrodes respectively.

(b) Coomassie dyes (R-250 and G-250) are used for staining proteins. They bind to proteins such as albumin through ionic interactions between dye sulfonic acid groups and positive protein amine groups. They also involve hydrophobic interactions and Van der Waals forces of attraction.

(c) Albumin appears to be most intense which further indicates its highest concentration in the sample.

(d) Second band from (+) end, adjacent to albumin will be the DNA band. Since DNA is positively charged it moves towards positive end.

(e) Immunoglobulins are present in abundance which indicates provoked immune response by the patient.

5.

Negative (-) end at sample well (top of the gel).

RNA with largest size will move least in the gel while shorter RNA move faster in the gel. The order of RNA from top to bottom will be:

28 S RNA

18 S RNA

5.8 S RNA

5 S RNA

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