Question

Choose the incorrect statement for second DNA strand synthesis.

(a) The RNA: DNA complex is treated with the enzyme RNaseH and DNA pol

(b) The enzyme RNaseH is responsible for nicking the RNA strand and leaving free 3’ hydroxyl ends

(c) These RNA fragments can be used as primers

(d) There is no portion of RNA left attached to the DNA strand

I have been asked this question in an online quiz.

I'd like to ask this question from cDNA Libraries, Polyadenylated RNA and cDNA Synthesis topic in chapter Libraries Construction of Genetic Engineering

Answer 1

Right answer is (d) There is no portion of RNA left attached to the DNA strand

For explanation I would say: For second strand DNA synthesis, the RNA: DNA complex is treated with RNaseH enzyme along with DNA pol. The enzyme is responsible for nicking the RNA strand and leaving 3’ hydroxyl ends. These free ends are used for second strand synthesis. These RNA fragments can be used as primers. After DNA: DNA duplex formation, only a small portion of RNA is left at the 5’ end.