Question

Compare the structural features of a double-stranded RNA structure with those of a DNA double helix.

Short answer

Essentially, both DNA and double-stranded RNA possess a double helix structure and antiparallel arrangement. However, they differ in terms of the sugar within the backbone (deoxyribose in DNA and ribose in RNA), the base pairing (adenine to thymine in DNA and adenine to uracil in RNA), and the structure of the grooves. The major and minor grooves of DNA are more defined consistently, while RNA is variable in size and shape.

Step-by-step solution

Understanding the structure of DNA

DNA (deoxyribonucleic acid) is a molecule composed of two chains that coil around each other to form a double helix, held together by hydrogen bonds between the nitrogenous bases. The structure is antiparallel and the pairing in DNA is Adenine (A) with Thymine (T) and Cytosine (C) with Guanine (G). The phosphate-deoxyribose backbone is on the outside and the bases are facing inwards.

Understanding the structure of Double-stranded RNA

Double-stranded RNA (dsRNA) is less common in nature than double-stranded DNA but it can be found in some viruses. Similar to DNA, dsRNA is composed of two strands of RNA that are bound together by hydrogen bonds between complementary base pairs. The structure is antiparallel as well. But instead of Thymine (T), RNA contains Uracil (U), so the base pairing in dsRNA is Adenine (A) with Uracil (U) and Guanine (G) with Cytosine (C). The phosphate-ribose sugar backbone is on the outside of the structure.

Comparing the two structures

Both DNA and dsRNA have a double helix structure and have an antiparallel arrangement but they differ in a few ways including: The sugar in the backbone of DNA is deoxyribose while in RNA it's ribose. The nucleotide thymine in DNA is replaced by uracil in RNA. The major and minor grooves of DNA are structurally more defined, being a consistent size throughout, whereas RNA is more variable in size and shape. dsRNA can create a variety of twisted shapes, unlike DNA which generally stays in the same twisted ladder shape.