Which is wrong about nucleic acids? (a) DNA is single straanded in some viruses (b) RNA is double stranded occasionally .

Question

Which is wrong about nucleic acids?

(a) DNA is single stranded in some viruses

(b) RNA is double stranded occasionally

(c) Length of one helix is 45 Å in B-DNA

(d) One turn of Z-DNA has 12 bases

Answer 1

Correct option (c) Length of one helix is 45 Å in B-DNA

Explanation :

Length of one helix or the pitch per turn of helix is 34 Å in B-DNA, 25 Å in A-DNA and 46 Å in Z-model of DNA. In Z-DNA sugar moieties are seen in opposite direction. So the 3-5 diester bond forms zig-zag structure in Z-DNA.