Question

there are several levels of structure for each class of biomolecules you have studied. which statements accurately describe their secondary structures? select all that apply. the secondary structure of dna is a double - helix which is stabilized by ionic bonds between the negatively - charged phosphate groups in the sugar - phosphate backbone. rna does not have secondary structure because it is single - stranded. the secondary structure of proteins is stabilized by hydrogen bonds, ionic bonds, and covalent bonds between amino acid r - groups. the secondary structure of dna is a double - helix which is stabilized by complementary base - pairing between a - t and g - c pairs. the secondary structure of proteins is the formation of alpha - helices and beta - sheets. the secondary structure of rna is made up of stem - loop structures stabilized by covalent bonding between a - u and g - c pairs.

Explanation:

1. The secondary structure of DNA is a double - helix stabilized by complementary base - pairing between A - T and G - C pairs, not by ionic bonds between phosphate groups in the sugar - phosphate backbone.
2. RNA can have secondary structure like stem - loop structures stabilized by base - pairing (not covalent bonding between A - U and G - C pairs in the typical sense of covalent bonds in this context). It is false that RNA has no secondary structure just because it is single - stranded.
3. The secondary structure of proteins involves the formation of alpha - helices and beta - sheets, and it is stabilized mainly by hydrogen bonds between the backbone atoms, not by ionic and covalent bonds between R - groups (which are more involved in tertiary and quaternary structures).

Answer:

D. The secondary structure of DNA is a double - helix which is stabilized by complementary base - pairing between A - T and G - C pairs.
E. The secondary structure of proteins is the formation of alpha - helices and beta - sheets.