Question

A transcription unit in DNA is defined primarily by the three regions in DNA and these are with respect to upstream and down stream end;

• A. Repressor, Operator gene, Structural gene
• B. Structural gene, Transposons, Operator gene
• C. Inducer, Repressor, Structural gene
• D. Promotor, Structural gene, Terminator

Answer 1

The Correct Option is D

A transcription unit in DNA is defined primarily by the three regions in DNA and these are with respect to upstream and down stream end;

Option 4: Promoter, Structural gene, Terminator

Explanation:

A transcription unit in DNA is the segment of DNA that is transcribed into RNA. It is defined by three key regions:

1. Promoter:

The promoter is a DNA sequence located upstream (5') of the structural gene. It is the binding site for RNA polymerase, which initiates transcription. It determines where transcription begins.

2. Structural gene:

The structural gene is the DNA sequence that is transcribed into RNA. It contains the coding information for the protein or RNA product.

3. Terminator:

The terminator is a DNA sequence located downstream (3') of the structural gene. It signals the end of transcription, causing RNA polymerase to detach from the DNA template.

Therefore, the correct regions are promoter, structural gene, and terminator.

Let's look at why the other options are incorrect:

• Repressor, Operator gene, Structural gene: These are components of the lac operon, a specific type of gene regulation system. They are not the general components of a transcription unit.
• Structural gene, Transposons, Operator gene: Transposons are mobile genetic elements and are not part of the basic definition of a transcription unit.
• Inducer, Repressor, Structural gene: Inducers and repressors are involved in gene regulation, specifically in operons. They are not the basic components of a transcription unit.