Exam 2 Answers
Biol 385: Biotech. and Gen. Eng. Name ___________________________
Exam #2 - 100pts 06 April 2012 G # _____________________
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If necessary, use the back of the exam pages for the rest of your answers. Do not use other sheets of paper. Please write legibly; if I cannot read your answer, I will count it wrong. * BY TAKING THIS EXAM, YOU HAVE AGREED TO ABIDE BY THE SPIRIT AND THE LETTER OF THE HONOR CODE OF GEORGE MASON UNIVERSITY. INITIAL HERE
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1. (6pts) Expression of eukaryotic proteins in prokaryotic cells occasionally results in instability or lack of biological activity. What are three of the post-translational modifications that eukaryotic cells can carry out that prokaryotic cells cannot?
a)
b)
c)
Correct disulfide bond formation
Proteolytic cleavage of inactive precursor
See Fig 7.1 p241 for cleavage of preproinsulin
Glycosylation - addition of sugar residues
See Fig 7.2, 7.3 p. 242,243 in text
Modification of amino acids in protein
Phosphorylation // acetylation
Sulfation // fatty acid addition
2. (7pts) Answer the following questions regarding “error-prone” PCR:
a) What is “error-prone” PCR?
Use of the PCR under conditions that promote the insertion of an incorrect nucleoticde every few hundred or so nucleotides of the template. Used as a method of random mutagenesis.
b) What is one reaction condition of PCR that can enhance the error-rate of PCR?
in presence of Mn2+ // Unequal dNTP concentrations // Increased Mg2+ concentration
c) When would you use this method?
This method would be used when the specific amino acid to be altered isn’t known, but the general region to be mutated is known. Say, for example, the region of the active site or allosteric regulation, but not specific amino acids.
Yields a library
Exam #2 - 100pts 06 April 2012 G # _____________________
=======================================================================
If necessary, use the back of the exam pages for the rest of your answers. Do not use other sheets of paper. Please write legibly; if I cannot read your answer, I will count it wrong. * BY TAKING THIS EXAM, YOU HAVE AGREED TO ABIDE BY THE SPIRIT AND THE LETTER OF THE HONOR CODE OF GEORGE MASON UNIVERSITY. INITIAL HERE
=======================================================================
1. (6pts) Expression of eukaryotic proteins in prokaryotic cells occasionally results in instability or lack of biological activity. What are three of the post-translational modifications that eukaryotic cells can carry out that prokaryotic cells cannot?
a)
b)
c)
Correct disulfide bond formation
Proteolytic cleavage of inactive precursor
See Fig 7.1 p241 for cleavage of preproinsulin
Glycosylation - addition of sugar residues
See Fig 7.2, 7.3 p. 242,243 in text
Modification of amino acids in protein
Phosphorylation // acetylation
Sulfation // fatty acid addition
2. (7pts) Answer the following questions regarding “error-prone” PCR:
a) What is “error-prone” PCR?
Use of the PCR under conditions that promote the insertion of an incorrect nucleoticde every few hundred or so nucleotides of the template. Used as a method of random mutagenesis.
b) What is one reaction condition of PCR that can enhance the error-rate of PCR?
in presence of Mn2+ // Unequal dNTP concentrations // Increased Mg2+ concentration
c) When would you use this method?
This method would be used when the specific amino acid to be altered isn’t known, but the general region to be mutated is known. Say, for example, the region of the active site or allosteric regulation, but not specific amino acids.
Yields a library