Question

1. Discuss what you understand by the term 'promoter' in the context of transcription? (500 words)

Answer 1

Answer:

Transcription - it is the synthesis of mRNA using DNA as template, by the enzyme RNA polymerase.

Enzyme RNA polymerase transcribes the gene into the mRNA

In case of Transcription in prokaryotes:

1. The gene shows following parts as - Promotor, Operator, Start Point (+1 site), Coding Region and Terminator.
2. Promotor is the Binding Site for RNA polymerase to initiate transcription
3. Promotor region is located between -10 and -35 base pairs upstream of Start Point
4. Upstream region at -10 has highly conserved sequence TATAAT (TATA Box),
5. While -35 region has sequence TTGACA.
6. The region upstream of promotor is called as Enhancer
7. RNA polymerase recognizes the this promotor region bind to promotor, Specificity of this binding is regulated by Sigma factor. Sigma factor is highly specific to -35 sequence.

In case of Transcription in eukaryotes:

• Promotor is located at -25 to -35 upstream of the Start point (+1 site), This sequnce resembles to -10 sequence of prokaryotes.