Multiple Choice
True or false: The following proteins with identical composition are certain to have the same shape/function.
Protein #1: L-G-T-V-R-D Protein # 2: D-R-V-T-G-L
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4. Protein Structure
Altering Primary Protein Structure
Multiple Choice
Which amino acid is least likely to alter protein shape/function if substituted with an Arg residue?
A
Lys
B
Tyr
C
Asn
D
Ala
Verified step by step guidance1
Identify the properties of the amino acid Arginine (Arg). Arginine is a positively charged, polar amino acid with a long side chain.
Consider the properties of each amino acid option: Lysine (Lys), Tyrosine (Tyr), Asparagine (Asn), and Alanine (Ala).
Lysine (Lys) is similar to Arginine as it is also a positively charged, polar amino acid with a long side chain, making it more likely to substitute without altering protein shape/function.
Tyrosine (Tyr) is a polar amino acid but has a bulky aromatic side chain, which differs significantly from Arginine.
Asparagine (Asn) is polar but uncharged, and Alanine (Ala) is nonpolar with a small side chain, both differing from Arginine in charge and/or size, making them less likely to substitute without altering protein shape/function.
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