problemset3KEY - PROBLEM SET 3 ANSWER KEY FALL 2007 MCB102...

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PROBLEM SET 3 ANSWER KEY FALL 2007 MCB102 Collins Multiple choice, for warm-up 1. The average molecular weight of the 20 standard amino acids is 138, but biochemists use 110 when estimating the number of amino acids in a protein of known molecular weight. Why might this be? A) The number 110 is based on the fact that the average molecular weight of a protein is 110,000 with an average of 1,000 amino acids. B) The number 110 reflects the proportional representation of amino acids in known proteins, in the context of polypeptide linkage. this is the correct answer (condensation reduces molecular weight but the empirically observed average is yet lower) C) The number 110 takes into account the relatively small size of nonstandard amino acids. D) The number 138 represents the average molecular weight of amino acids after incorporation into polypeptide, following peptide bond formation. 2. In a mixture of the five proteins listed below, which should elute second in size-exclusion (gel- filtration) chromatography? A) cytochrome c M r = 13,000 B) immunoglobulin G M r = 145,000 this is the correct answer. C) ribonuclease A M r = 13,700 D) RNA polymerase M r = 450,000 E) serum albumin M r = 68,500 3. The interactions of ligands with proteins: A) are relatively nonspecific. B) are relatively rare in biological systems. C) are usually irreversible. D) are usually transient. this is the correct answer. E) usually result in the inactivation of the proteins. 4. When oxygen binds to a heme-containing protein, the two open coordination bonds of Fe
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This note was uploaded on 04/02/2008 for the course MCB 102 taught by Professor Staff during the Spring '08 term at University of California, Berkeley.

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problemset3KEY - PROBLEM SET 3 ANSWER KEY FALL 2007 MCB102...

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