Final answer:
The first step for both DNA replication and transcription is for the DNA to unzip down the middle, a process started by the enzyme helicase.
Step-by-step explanation:
The first step for both replication and transcription is for DNA to "unzip" or split down the middle. This is facilitated by the enzyme helicase, which breaks the hydrogen bonds between base pairs, allowing the two strands of the DNA helix to separate and serve as templates for the process that follows. In replication, this leads to the formation of replication forks where new nucleotides are added to form new DNA strands. During transcription, the separation of the DNA strands allows RNA polymerase to synthesize RNA by reading one strand of the DNA.