Which molecule is primarily responsible for the transcription step in protein synthesis?

• A. DNA
• B. mRNA
• C. tRNA
• D. ribosomes

Answer: (B)

The transcription step in protein synthesis primarily involves mRNA, which is synthesized from a DNA template. During transcription, the DNA strand unwinds, and RNA polymerase enzymes facilitate the assembly of ribonucleotides into a single strand of mRNA that is complementary to the DNA template. This mRNA strand carries the genetic information necessary for protein synthesis from the nucleus to the ribosomes, where translation occurs.

While DNA provides the template for transcription, it is the mRNA that is created during this process and serves as the intermediary that conveys the genetic instructions for translating into proteins. The other molecules involved in protein synthesis, such as tRNA and ribosomes, play roles in the later stages of translation rather than in the transcription step itself.