SOLVED

31)Define what is meant by “isoelectric point” (pI) and give an example. 32)Which of the following amino acids has its isoelectric point at the lowest pH? A)glutamic acid B)lysine C)valine D)glycine E)methionine 33)What is the pI of arginine? The structure and pKa values are shown below. A)10.76 B)7.90 C)5.61 D)7.33 E)9.67 34)What is “electrophoresis”? A)a technique that separates amino acids on the basis of their polarity B)a technique that separates amino acids on the basis of their solubility in water C)a technique that separates amino acids on the basis of their pI values D)a technique that separates amino acids on the basis of pKa of α-COOH values E)a technique that separates amino acids on the basis of pKa of α-+NH3 values 35)What is “thin-layer chromatography”? A)a technique that separates amino acids on the basis of their polarity B)a technique that separates amino acids on the basis of their solubility in water C)a technique that separates amino acids on the basis of their pI values D)a technique that separates amino acids on the basis of pKa of α-COOH values E)a technique that separates amino acids on the basis of pKa of α-+NH3 values 36)Rank the following amino acids in decreasing order of migration towards the cathode (negative electrode) when separated by electrophoresis in a solution of pH= 7.3. I.Lysine: pI= 9.87 II.Alanine: pI= 6.02 III.Aspartate: pI= 5.95 37)What is an “amino acid analyzer”? 38)Describe how electrophoresis works. 39)You are given a mixture that contains glutamic acid (pI = 3.2), arginine (pI = 10.8), and valine (pI = 6.0), and you subject the mixture to electrophoresis. a)Which amino acids migrate toward the cathode when the electrophoresis is carried out at a pH of 7.1? b)Which amino acids migrate toward the anode when the electrophoresis is carried out at a pH of 7.1? c)Which amino acid migrates farthest toward the anode at a pH of 7.1? d)Since amino acids themselves are colorless, how is the separation of amino acids after electrophoresis detected? 40)Rank the following amino acids in order of time of elution from a cation-exchange resin and a buffer p