You are investigating the biochemistry of DNA replication. You add radioactive dNTP nucleotides and unlabeled template (1000 bp double-stranded DNA) to a cell lysate containing all cellular contents. You take samples at various time points and examine the sizes of radioactive DNA after removing the nucleotides, under denaturing conditions in which all DNA is single-stranded. Time (sec) | Radioactive DNA ------------|---------------- 0.0 | none 0.25 | 250 bases, 10 bases 0.5 | 500 bases, 50 bases 1.0 | 1000 bases, 50 bases, 100 bases 1.5 | 1000 bases, 50 bases, 100 bases, 250 bases, 500 bases 2.0 | 1000 bases, 250 bases, 500 bases 3.0 | 1000 bases

1. After DNA replication is complete (3 seconds), what percent of the DNA molecules have both strands radiolabeled?
2. What percent have only one strand radiolabeled?
3. Explain why you see small radiolabeled DNA molecules at the intermediate time points, and what happened to those small molecules.
4. Is the template DNA you added linear or circular? Explain your logic.

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