Question

Arrange the following in order 5' - 3' direction
A. Promoter
B. UTR5'
C. ORF
D. Termitor

• A. A, B, C, D
• B. A, C, B, D
• C. A, D, B, C
• D. A, C, D, B

Hint:

Gene Structure ($5' \to 3'$ Direction):
Promoter $\to 5'$-UTR $\to$ ORF (Coding Region) $\to 3'$-UTR $\to$ Termitor.

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
The question asks to arrange the functiol regulatory and coding elements of a gene transcription unit in sequential order from the $5'$ end to the $3'$ end.

Step 2: Key Formula or Approach:
A functiol eukaryotic transcription unit displays structural organization along the sense strand in the $5' \to 3'$ orientation: \[ 5'\text{-Promoter (A)} \to 5'\text{-UTR (B)} \to \text{ORF (C)} \to 3'\text{-Termitor (D)}-3' \]

Step 3: Detailed Explation:

• 1. Promoter (A): Upstream regulatory sequence located at the extreme $5'$ end of the transcription unit, serving as the binding site for transcription factors and R polymerase.

• 2. 5'-UTR (B): $5'$ UnTranslated Region located downstream of the transcription start site but upstream of the translation initiation codon (AUG).

• 3. ORF (C): Open Reading Frame containing continuous protein-coding codons extending from the start codon to the stop codon.

• 4. Termitor (D): Downstream sequence located at the extreme $3'$ end that sigls transcription termition and pre-mR cleavage/polyadenylation.

Step 4: Fil Answer:
The correct $5' \to 3'$ order of gene elements is A, B, C, D.