BMBN6-07 - BMB 401 EXAM 6 July 28, 2006 NAME_ 1. 2. Please...

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BMB 401 EXAM 6 July 28, 2006 NAME__________________________________________________________________ 1. Please circle all of the pyrimidine bases shown below: Uracil Cytosine Thymine 2. Nucleotides serve the following purposes EXCEPT : a. are an important part of second messenger systems b. change chemical energy to mechanical energy by inducing conformational changes in proteins c. provide energy for reactions d. transfer electrons in chemical reactions e. store and transmit genetic information f. all the above are true of nucleotides 3. In an experiment done in E. coli to determine the directionality of replication, radiolabeled thymidine tri-phosphate (dTTP) was added to bacterial cells to determine where nucleotides were added. This was followed by a “chase” of unlabeled thymidine tri-phosphate to limit background labeling. This way only the new DNA, synthesized at the replication fork, would be labeled. Which of the following would you expect to see? a. The radio-labeled thymidylate was incorporated into one strand in a 5’ to 3’ direction and labeled only one replication fork b. The radio-labeled thymidylate was incorporated in both the upper and lower strands and labeled only one replication fork c. The radio-labeled thymidylate was not incorporated in either the upper and lower strand because the chase washed it away, thus proving that replication had happened d. The radio-labeled thymidylate was incorporated in both the upper and lower strand and labeled two replication forks 4. If you were to do the same experiment in Yeast, what would you see? a. There would be no labeling, as the chase would have replaced it, showing that replication had occurred b. The results would show exactly the same thing as seen in E. coli, because yeast, being unicellular, are similar to E. coli c. As Yeast are eukaryotes, there would be several bidirectional replication forks per chromosome d. There would be one unidirectional replication fork per chromosome e. There would be one bidirectional replication fork per chromosome 5. Origin of replication in Bacteria has: a. binding sites for dnaA protein b. a GC–rich consensus sequence c. A binding site for pol δ d. all the above 1 Note: thymidine monophosphate = thymidylate cytosine monophosphate = cytidylate adenine monophosphate = adenylate guanosine monophosphate = guanidylate Radioactively Labeled DNA Original DNA 4a 4b 4c 4d
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BMBN6-07 - BMB 401 EXAM 6 July 28, 2006 NAME_ 1. 2. Please...

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