The genome size of e. coli is approximately 5x106 bp and can be replicated in 30 minutes. the human genome size is 3x109 bp, about 600 times larger, and should take 300 hours (~13 days) to replicate based on the bacterial rate of replication. however, the entire human genome is replicated within few hours

Human genome has various replicons.

Explanation:

A replicon which is a unit of DNA, has potential to get replicated independently. So, the DNA replication occurs simultaneously at various replicons as a result of which human genome takes much less time than estimated to get replicated .

In contrast to this, prokaryotes like E.coli have only one origin of replication and thus one replicon due to which replication is restricted to once per cell cycle.

substitution is the answer in this case

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