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Multiple Choice
What makes one amino acid different from another?
A
The number of peptide bonds it can form
B
The presence of a carboxyl group
C
The presence of an amino group
D
The side chain (R group) attached to the alpha carbon
Verified step by step guidance
1
Understand that amino acids are the building blocks of proteins, and each amino acid has a general structure consisting of a central alpha carbon (Cα) bonded to four different groups: an amino group (-NH₂), a carboxyl group (-COOH), a hydrogen atom, and a variable side chain known as the R group.
Recognize that the amino group and the carboxyl group are common to all amino acids, meaning they do not contribute to the differences between amino acids.
Identify that the R group, or side chain, is the variable part of the amino acid structure. It is this group that differs among the 20 standard amino acids, giving each one unique chemical properties.
Consider how the R group can affect the amino acid's characteristics, such as its polarity, charge, and reactivity, which in turn influence the protein's structure and function.
Conclude that the primary factor distinguishing one amino acid from another is the nature of its side chain (R group) attached to the alpha carbon, as this is the only part of the amino acid that varies.