Question

Choose the correct answer from the alternatives given:
The enzyme DNA dependent RNA polymerase catalyzes the polymerization reaction in __________ direction.
(a)Only 5 → 3
(b)Only 3 → 5
(c)Both (a) and (b)
(d)None of these

Answer 1

Hint: DNA has two-strand one is in $5’\rightarrow 3’$ direction and the other in $3\rightarrow 5$ direction. One strand forms a continuous strand and the other forms a discontinuous strand. Continuous strand is the leading strand while discontinuous is the lagging strand. Only one strand of DNA gives rise to an RNA strand.

Complete answer:
In living cells DNA form RNA and RNA form protein by sharing genetic information from one nucleic acid to another, but the process of formation and enzyme that is used to catalyze reaction is different. The process of the formation of RNA from DNA is called transcription.
In transcription a single strand of RNA is formed from DNA, the only difference between both of the strands is the amino acid thymine in DNA is replaced by uracil in RNA. The transcription process proceeds in $5\rightarrow 3$ directions. For this process DNA dependent, RNA polymerase enzyme is used to catalyze the reaction in $5\rightarrow 3$ direction. RNA polymerase acts only on the template strand of DNA which is also known as the Transcription start site.
In prokaryotes, single RNA polymerase is used while in the case of Eukaryotes three type of RNA polymerase is used RNA polymerase I, RNA polymerase II and RNA polymerase III, and all this polymerase have a different function.

Additional Information: Formation of DNA takes place by replication where two strands of DNA replicate with the help of DNA dependent DNA polymerase and a new strand of DNA form, where both strands unwind and replica form. Both of the strands are functional in DNA.
In the case of protein the three RNA enzymes- mRNA, tRNA, and rRNA become functional as per need, and the formation of protein takes place by process translation. In translation, information is translated from mRNA in the form of the polypeptide chain of amino acid which forms protein and works as per the information given.

So, the correct answer is only $5\rightarrow 3$ directions.

Note: If both strands of DNA will take part in transcription then two RNA strands form in the opposite direction which gives rise to two protein polypeptides with opposite information which will cause defunctioning and defect in the living cells.
But in the case of the RNAi technique double RNA strand produces as sense and antisense RNAs. This type of RNA is used to silence the mRNA of nematodes which cause tumors in the plant. RNAi technique is also useful to control cancer, HIV, and hepatitis.