Gene Definition and DNA Location — NEET Biology
📚 Practice ConceptA gene is defined as the functional unit of inheritance. Though there is no ambiguity that the genes are located on the DNA, it is difficult to literally
Which of the following statements regarding a transcription unit in DNA are NOT correct? S1: The promoter region is located towards the 5'-end (upstream) of the structural gene with respect to the polarity of the coding strand. S2: The template strand serves as the direct coding sequence for the polypeptide, with its sequence being identical to the mRNA. S3: In prokaryotes, a single transcription unit can often be polycistronic, encoding multiple structural genes. S4: The terminator sequence is located towards the 5'-end (upstream) of the coding strand and defines the end of transcription. S5: Regulatory sequences, such as enhancers, are considered primary defining components of a transcription unit along with the promoter, structural gene, and terminator.
View solution & NCERT explanation
Correct answer: B — S2, S4, S5 only
The core concept tested is the structure and components of a transcription unit and the roles of its DNA strands. S1: Correct. According to NCERT, "The promoter is said to be located towards 5'-end (upstream) of the structural gene (the reference is made with respect to the polarity of coding strand)". S2: Incorrect. The coding strand has a sequence identical to the mRNA (except T for U), not the template strand. The template strand is complementary to the mRNA and is transcribed. S3: Correct. NCERT states, "the structural gene in a transcription unit could be said as monocistronic (mostly in eukaryotes) or polycistronic (mostly in bacteria or prokaryotes)". S4: Incorrect. The terminator is located towards the 3'-end (downstream) of the coding strand. NCERT says, "The terminator is located towards 3'-end (downstream) of the coding strand and it usually defines the end of the process of transcription". S5: Incorrect. NCERT defines a transcription unit primarily by three regions: promoter, structural gene, and terminator. It states that "There are additional regulatory sequences that may be present further upstream or downstream to the promoter", indicating they are not primary defining components. Therefore, statements S2, S4, and S5 are NOT correct. The final answer is B because S2, S4, and S5 are the incorrect statements. The question assesses the understanding of the specific roles and locations of components within a transcription unit.
What does NCERT say about gene defined as functional?
Has this concept appeared in NEET?
Which chapter is this from?
Through deep analysis of NEET and NTA, 176 of the 180 ReNEET 2026 (June 21) questions were already in the MedicNEET question bank before the exam.
176/180MedicNEET's Biology question bank is built from the same NCERT lines NTA picks repeatedly. Not random MCQs — questions crafted exactly like NTA crafts them.