BCHM 561 exam 2 - BCHM 561 EXAM II Fall 2009 NAME (please...

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- 1 - NAME ( please print clearly ) Please write legibly in the space provided. If additional space is needed to write your answers, use the back of the pages provided making sure you include the question number. The total points assigned to each question are enclosed in brackets. There are a total of 200 points. DNA, RNA, and the Flow of Genetic Information (Chapter 4) 1. [4] Why does the absorbance of a solution of DNA at 260 nm increase when the temperature is increased? 2. [6] Using purified DNA polymerase, the four deoxynucleoside 5´-triphosphates, a 200 bp template, a 10 bp primer complementary to the template, and all the other required components, a researcher is able to synthesize a new DNA chain of about 190 bp. However, when the nucleotide derivative shown below was used in place of dATP, the newly synthesized DNA strand contained only 9 bp. Explain why the reaction containing this nucleotide derivative yields a short, 9-bp product? 3. [4] Which of the following is not required for the synthesis of RNA from a DNA template ? A. RNA polymerase B. four ribonucleoside triphosphates ATP, GTP, UTP, CTP C. a short primer strand that hybridizes with the template strand and has a free 3´-OH group D. a double-stranded DNA template E. Mg 2+ BCHM 561 EXAM II Fall 2009 As the temperature increases, the two complementary strands of the DNA double helix separate and DNA is converted to a denatured state. Base stacking in the intact DNA double helix suppresses the UV absorbance (at 260 nm) of the bases, a phenomenon known as hypochromism. Thus, strand separation is accompanied by an increase in absorbance as single- stranded DNA is formed. Since this derivative is a deoxynucleoside triphosphate, DNA polymerase will incorporate it into the newly synthesized nucleotide chain. However, once incorporated it will terminate further chain elongation because it lacks the 3´- OH group absolutely required for formation of a phosphodiester bond with the next nucleotide specifed by the template. This accounts For termination of the chain at the 9th bp, which is the frst A in the new chain (T in the template).
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- 2 - 4. [5] Briefly, describe the reaction catalyzed by reverse transcriptase . 5. [5] Assume the short segment of double-stranded DNA shown below is transcribed into RNA by RNA polymerase. Write the sequence of the RNA product that is produced. 5´-ATGGTACGCGTAG-3´ 3´-TACCATGCGCATC-5´ 6. [8] Assume that RNA polymerase has all the necessary factors including the nucleoside triphosphates (ATP, GTP, UTP, CTP) required to successfully transcribe a DNA template into RNA. A. If the gamma ( γ ) phosphate of all four nucleotides is radiolabelled with 32 P, will the RNA synthesized be radioactive and contain 32 P? Explain your answer. Yes
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This note was uploaded on 02/02/2010 for the course BCHM 561 taught by Professor Mr. during the Spring '10 term at Purdue University-West Lafayette.

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BCHM 561 exam 2 - BCHM 561 EXAM II Fall 2009 NAME (please...

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