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DNA Replication and Repair

Problems

DNA Replication

The Chemistry of the Addition of Substrates of DNA Replication

Problem : Why is DNA replication called "semi-conservative"?

DNA replication is semi-conservative because each helix that is created contains one strand from the helix from which it was copied. The replication of one helix results in two daughter helices each of which contains one of the original parental helical strands. It is semi- conservative because half of each parent helix is conserved in each daughter helix.

Problem : The number of replication forks in a DNA helix is often an even number. Explain this finding.

Since replication origins are usually not found at the end of a helix, but rather internally to a helix, one replication origin leads to the formation of two replication forks. Replication forks, thus, are usually found in pairs.

Problem : In what direction (5' to 3' or 3' to 5') does biological DNA replication take place?

Biological DNA replication ALWAYS takes place in the 5' to 3' direction.

Problem : The strand on which DNA replication is continuos is called the ___________. The strand on which DNA replication is discontinuous is called the ___________.

Leading strand. Lagging strand.

Problem : Replication on the lagging strand is mediated by small segments of nucleotides called what?

Okazaki fragments.

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