2011 L3-4 practice problems

2011 L3-4 practice problems - MCB121 W11 Practice problems...

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MCB121 W11 Practice problems for Lectures 3-4 1. The clamp is a multimeric protein complex that has a donut-shaped structure with a center hole large enough to encircle a DNA double helix and a layer of water molecules. This complex can also interact with DNA polymerase. These two features combined serve to increase processivity of DNA pol δ. Describe briefly how these two features work together to contribute to increasing the processivity of DNA pol δ ? 2. DNA replication of chromosomal DNA is semi-conservative. What is the meaning of this term? 3. List six enzymatic or non-enzymatic activities acting at or near the replication fork during replication. 4. Draw the nucleic acids of a single replication fork, identifying and specifically labeling newly synthesized strands by name, labeling all relevant 5’ and 3’ ends, indicating the direction of fork movement with an arrow, and identifying the location of any RNA by use of a crooked line. 5. You are investigating DNA synthesis in a mammalian tissue culture line and perform the following analysis. You synchronize the cells by arresting in G1 of the cell cycle (prior to DNA replication) followed by release from arrest. Thirty minutes following release you incubate cells with high levels of 3 H-labeled thymidine. After 15 minutes of labeling you change the medium to reduce the concentration of label and incubate an additional 15 minutes. You visualize the incorporated label on an autoradiograph of the replicating DNA and see the following patterns. A. On the diagram above, solid lines show high incorporation of 3 H-labeled thymidine while the dashed lines represent reduced levels of label. Mark the likely site of all origins and replication forks. Specify the origin(s) from where each fork initiated replication. B. Draw what the pattern would look like if only one replication fork was generated per origin firing
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2011 L3-4 practice problems - MCB121 W11 Practice problems...

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