(Solved) 2 Questions about DNA

livestrong136

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12 years ago

1. Eukaryotic DNA has several origin sites for replication. Explain why this is the case.

2. If one cell is isolated and all the cytosine molecules are labelled with a radioactive tag and then allowed to undergo DNA replication with normal nucleotides, how much radioactive cytosine would be found in the daughter cell DNA and in the next generation’s DNA?

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bio_man

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12 years ago

Quote from: livestrong136 (12 years ago)

1. Eukaryotic DNA has several origin sites for replication. Explain why this is the case.

DNA needs to replicate as soon as possible. If you have one replication bubble, it will take far too long to replicate the whole molecules. However, if you have multiple replication bubbles, several sites on the DNA are being replicated at the same time, reducing the amount of time needed to copy the whole molecule.

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sarahpiphi

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12 years ago

1. The average human chromosome contains 150 x 106 nucleotide pairs which are copied at about 50 base pairs per second. The process would take a month (rather than the hour it actually does) but for the fact that there are many places on the eukaryotic chromosome where replication can begin. Replication begins at some replication origins earlier in S phase than at others, but the process is completed for all by the end of S phase. As replication nears completion, "bubbles" of newly replicated DNA meet and fuse, finally forming two new molecules.

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Mahnoor Ehsan

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Pantz

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12 years ago

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1. Eukaryotic DNA has several origin sites for replication. Explain why this is the case.

Because that's just the way it is (we don't do "why" questions very well).

But it's advantageous in that it increases the speed with which the DNA can be replicated. A eukaryotic chromosome is really long, and would take a really long time to replicate if there were only one origin of replication.

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livestrong136 Author

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12 years ago

Can anyone answer #2 please. THANKS ALOT GUYS

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duddy

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2 Questions about DNA

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