Question

Select the correct option.

Direction of RNA synthesis		Direction of reading of the template DNA strand
(1)	3' — 5'	5' — 3'
(2)	5' — 3'	5' — 3'
(3)	3' — 5'	3' — 5'
(4)	5' — 3'	3' — 5'

• A. 1
• B. 2
• C. 3
• D. 4

Answer 1

The Correct Option is D

To understand the correct option for the direction of RNA synthesis and the direction of reading of the template DNA strand, we need to delve into the process of transcription in molecular biology. 

During transcription, RNA polymerase reads the DNA template strand and synthesizes a complementary RNA strand. The directionality of this process is crucial:

1. The template DNA strand is read in the \(3' \rightarrow 5'\) direction because the RNA polymerase moves along the template strand in this manner.
2. The resulting RNA strand, which is complementary to the template strand, is synthesized in the \(5' \rightarrow 3'\) direction. This is a universal direction for nucleic acid synthesis due to the chemical nature of nucleotides and the enzymatic machinery involved.

Given these fundamental rules of transcription, let's analyze the options provided:

Direction of RNA synthesis		Direction of reading of the template DNA strand
(1)	3' — 5'	5' — 3'
(2)	5' — 3'	5' — 3'
(3)	3' — 5'	3' — 5'
(4)	5' — 3'	3' — 5'

By observation and applying the above understanding, the correct option is Option 4:

• RNA Synthesis Direction: 5' — 3'
• DNA Template Reading Direction: 3' — 5'

This matches the biological process where RNA polymerase synthesizes RNA in the 5' — 3' direction while reading the DNA template strand in the 3' — 5' direction. Thus, option 4 correctly reflects the directionality of molecular processes involved in transcription.