The nucleotide where RNA polymerase actually begins synthesis of the mRNA.Group of answer choicespromoterintronstart pointA siteTATA boxcodonNext

To determine the correct nucleotide where RNA polymerase begins the synthesis of mRNA, it's important to understand the function of various elements involved in transcription.

1. Promoter: This is a specific region of DNA where RNA polymerase binds to initiate transcription. It contains specific sequences, which facilitate the recruitment of RNA polymerase.

2. Intron: These are non-coding sections of a gene that are removed during the processing of mRNA. They are not involved in the initiation of transcription.

3. Start Point: This is often referred to as +1 position in the transcription unit, marking the first nucleotide that is transcribed into RNA.

4. A site: Referring to the aminoacyl site in ribosomes, where tRNA brings amino acids during translation, not transcription.

5. TATA Box: A common element within the promoter region, often found about 25-30 nucleotides upstream of the start point. It helps in the binding of transcription factors.

6. Codon: A sequence of three nucleotides that corresponds to a specific amino acid or a stop signal during translation, but it is not involved in the initiation of transcription.

Final Answer

The nucleotide where RNA polymerase actually begins the synthesis of mRNA is referred to as the start point. Thus, the answer is start point.