Answer
Hi,
A. Radioactive markers
Explanation
Hershey and Chase used specific radioisotopes to form a trace of the two important components of the virus in its life cycle. The 32P was used to identify the DNA while the 35s labeled the proteins.DNA strands have a sugar phosphate where as protein contains sulfur.
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A unique feature of the nucleus is that it disassembles and re-forms each time most cells divide. At the beginning of mitosis, the chromosomes condense, the nucleolus disappears, and the nuclear envelope breaks down, resulting in the release of most of the contents of the nucleus into the cytoplasm.