Question

What are the differences between primary (or secondary, or tertiary) structures of RNA and DNA?

A) RNA has ribose sugar, DNA has deoxyribose; RNA is single-stranded, DNA is double-stranded; RNA has uracil, DNA has thymine
B) RNA has deoxyribose sugar, DNA has ribose; RNA is double-stranded, DNA is single-stranded; RNA has thymine, DNA has uracil
C) RNA has uracil, DNA has cytosine; RNA is double-stranded, DNA is single-stranded; RNA has deoxyribose, DNA has ribose
D) RNA has thymine, DNA has uracil; RNA is single-stranded, DNA is double-stranded; RNA has ribose, DNA has deoxyribose

Answer 1

RNA and DNA differ in sugar composition with ribose in RNA and deoxyribose in DNA, strand structure with RNA being single-stranded and DNA being double-stranded, and the use of uracil in RNA versus thymine in DNA. The correct option is A.

Step-by-step explanation:

The differences between the primary structures of RNA and DNA can be summarized as follows:

• RNA contains the sugar ribose, while DNA contains the sugar deoxyribose which lacks a hydroxyl group at the 2' position.
• RNA is generally single-stranded and can form complex three-dimensional structures through intramolecular base pairing, whereas DNA is double-stranded forming a stable helical structure.
• One of the nitrogenous bases in RNA is uracil (U), which pairs with adenine (A), instead of thymine (T), which is found in DNA.

These structural differences between RNA and DNA contribute to their distinctive functions in cells, with DNA serving as the long-term storage of genetic information and RNA being involved in various aspects of gene expression and protein synthesis.