Answer
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Work Step by Step
A train toy can be compared to a protein molecule. Assume that the train toy contains 20 bogies. These 20 bogies represent the individual amino acids in a protein. The head/engine is the N terminal and the tail is the C terminal. The links that connect the bodies represent the peptide bonds. The primary structure is the representation of each body sequence in the reservation list. The secondary structure represents the nature of local attachments among different bodies. Tertiary structure is the overall arrangement of the train. The quaternary structure represents all the decorations and other appendages attached to the train.
