Question

nucleic acids - dna or rna. chemically, they are similar. structurally, there are differences. which formula represents dna?
a
chemical structure diagram

b
chemical structure diagram

c
chemical structure diagram

d
chemical structure diagram

Explanation:

To determine which formula represents DNA, we analyze the structural differences between DNA and RNA. DNA has a deoxyribose sugar (lacks an -OH group on the 2’ carbon of the pentose sugar) and forms a double - helix structure with base - pairing (A - T, G - C). RNA has ribose sugar (with an -OH on the 2’ carbon) and is usually single - stranded.

• Option A: This structure does not resemble the nucleotide - based structure of nucleic acids (DNA or RNA). It looks more like a lipid or a different type of organic molecule, so it is not DNA.
• Option B: This is the structure of glucose, a monosaccharide, not a nucleic acid structure, so it is not DNA.
• Option C: The structure shows a double - stranded arrangement with nucleotide units. The pentose sugar in the nucleotides appears to be deoxyribose (consistent with DNA's sugar) and there are base - pairing interactions (like those in DNA's double helix), so this is consistent with the structure of DNA.
• Option D: This structure looks like a single nucleotide (or a part of a single - stranded nucleic acid). Since DNA is double - stranded and this structure does not show the double - helix or double - stranded base - paired structure, it is more likely to be a part of RNA or a single nucleotide, not DNA.

Answer:

C