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D) ligand-induced activation. 4. Starting with 1 mCi (millicurie) of a phosphoru

ID: 186794 • Letter: D

Question

D) ligand-induced activation. 4. Starting with 1 mCi (millicurie) of a phosphorus-32-labeled compound, how long would it take until only 0.125 mCi remains? A) 14.3 days B) 28.6 days C) 42.9 days D) 57.2 days 5. In two-dimensional gel electrophoresis, proteins are first resolved by and then by A) IEF; SDS-PAGE B) SDS-PAGE; affinity chromatography C) SDS-PAGE; ion exchange D) IEF; gel filtration 6. Kinases, which are responsible for the activation or inactivation of a number of proteins, serve to add phosphate groups onto A) tryptophan residues. B) serine residues. C) threonine residues. D) cysteine residues. E) b and c Page 1 of 3

Explanation / Answer

4. half life of P-32 is 14.3

1mCi/8= 0.125 mCi

23=8

14.33= 42.9

1mCi (in half life i.e in 14.3 years) will reduce to 0.5

0.5 (in another 14.3 i.e 28.6) will reduce to 0.25

0.25 (in another 14.3 i.e 42.9) will reduce to 0.125

5. A IEF and SDS

IEF isoelectric focussing is first employed to separate the proteins on the basis of pH. IEF the ph of the gel is varied and the protein stops at if characteristic pI because at that pH the overall charge is zero and hence the protein neither moves toward the positive or negative electrode. Once the pH stops at its pI, the gel is cut out and run on SDS page separating the polypetide chains of the protein

6. E. these kinases can be threonine kinases and serine kinases