20141007_StudyQuestions_answered.pdf

Isolate chromatin from gillyweed b add varying

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isolate chromatin from gillyweed b. add varying amounts of micrococcal nuclease to the chromatin and incubate all your samples for the same amount of time c. purify DNA away from proteins d. run your DNA out on a gel and stain it with ethidium bromide. You get the results pictured below. What do you conclude about the organization of gillyweed chromatin? How does it compare to chromatin in non-magical eukaryotes? First, you notice that the reaction carried out with the highest concentration of micrococcal nuclease gives you one broad band of about 300 bp in length. This suggests that nucleosome-like structures do form in gilleyweed, but that about 300 bp of DNA are protected by binding to protein. This is similar to the situation in non-magical eukaryotes, where about 200 bp of DNA are protected by binding to histones. However, you notice that you don’t see a ladder of DNA fragments appearing in any of these lanes. Recall that you This study resource was shared via CourseHero.com
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see the 200 bp ladder in non-magical eukaryotes because on average nucleosomes are evenly spaced across the entire genome (with about 200 bp of DNA per nucleosome + linker sequence). The smears you see in your gilleyweed samples suggest that the nucleosomes in this organism are not evenly spaced across the genome. 5. You want to set up an experiment where you assemble two nucleosomes on a single DNA molecule in vitro , incubating naked DNA with purified histone proteins. What is the minimal length of DNA you would choose for this experiment? (Circle the one best answer) a. 50 bp b. 100 bp c. 500 bp d. 1000 bp e. 5000 bp 6. Recall that when DNA is subjected to electrophoresis in an agarose gel, shorter molecules migrate faster than longer ones. In addition, closed-circular DNA molecules of the same size but with different degrees of supercoiling can also be separated on an agarose gel; topoisomers that are more supercoiled, and thus more condensed, migrate faster through the gel. In the gel shown below, purified plasmid DNA has migrated from top to bottom.
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