Question

the primary structure of a protein refers to the sequence of amino acids that are linked together in a long chain. which of the following common items would best represent the primary structure of a protein?
a. two unsharpened pencils held together by a piece of tape
b. a dry kitchen sponge sitting beneath a mound of table salt
c. a burning wax candle placed in front of a small fan
d. beads of different colors joined together on a piece of string

Explanation:

The primary structure of a protein is a linear sequence of amino acids (like beads) linked by peptide bonds (like the string). Option D best represents this linear, sequential arrangement. Options A, B, and C do not depict a linear sequence of distinct units joined together in a chain - like fashion as required to model the primary structure of a protein.

Answer:

D. Beads of different colors joined together on a piece of string