Question

Differentiate between: Promoter and terminator in a transcription unit.

Answer 1

Hint: The promoter and terminator flank the structural gene in a transcription unit. The promoter is located towards the 5-end of the structural gene. It is a DNA sequence that provides a binding site for RNA polymerase. On the contrary, the terminator is located towards the 3-end of the coding strand and it usually defines the end of the process of transcription.

Complete answer:
A promoter is a region of DNA where RNA polymerase binds to initiate transcription. A terminator is a sequence of DNA that causes RNA polymerase to terminate transcription. A transcription unit is the sequence between sites of initiation and termination by RNA polymerase; may include more than one gene.

Promoter	Terminator
1. Promoter sequences are DNA sequences that define where transcription of a gene by RNA polymerase begins	1. A transcription terminator is a section of nucleic acid sequence that marks the end of a gene or operon in genomic DNA during transcription.
2. Promoter sequences are typically located directly upstream or at the 5' end of the transcription initiation site.	2. Terminators are genetic parts that usually occur at the end of a gene or operon and cause transcription to stop.
3. Promoters are about 100-1000 base pairs long and are adjacent and typically upstream (5’) of the sense or coding strand of the transcribed gene.	3. This sequence mediates transcriptional termination by providing signals in the newly synthesized transcript RNA.
4. There are three main portions that make up a promoter: core promoter, proximal promoter, and distal promoter. Below describes the specifics of these regions in eukaryotic cells.	4. Two classes of transcription terminators, Rho-dependent and Rho-independent, have been identified throughout prokaryotic genomes. Two classes of transcription terminators, Rho-dependent and Rho-independent, have been identified throughout prokaryotic genomes.

Note: Transcription is the first of several steps of DNA based gene expression in which a particular segment of DNA is copied into RNA by the enzyme RNA polymerase. Both DNA and RNA are nucleic acids, which use base pairs of nucleotides as a complementary language.