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PTS: 1 TOP: Individual Amino Acids: Their Structures and Properties 2. Which ami

ID: 1089876 • Letter: P

Question

PTS: 1 TOP: Individual Amino Acids: Their Structures and Properties 2. Which amino acid takés on a negative charge when the R-group loses a proton? a. Glutamic Acid b. Histidine c. Glutamine d. Tyrosine e. Glutamic Acid and Tyrosine ANS: E TOP: Individual Amino Acids: Their Structures and Properties PTS: 1 OBJ: Modified from 5e Which amino acid takes on a positive charge when the R-group gains a proton a. Glutamic Acid 23. b. Histidine c. Glutamine d. Tyrosine e. Glycine ANS: B PTS: 1 OBJ: New in 6e TOP: Individual Amino Acids: Their Structures and Properties 24. Given the R-groups in the peptide, ALA-GLN-ARG-SER-HIS, it would likely be: a. Very water soluble

Explanation / Answer

Q no 22:-Option (e) is correct.
Both glutamic acid and tyrosine have functional groups in the R group that can be deprotonated.

carboxylic acid in the case of glutamic acid,

phenol in the case of tyrosine.

Qno 23:- option (b) is correct

Histidine which is an essential amino acid, has as a positively charged imidazole functional group. This is because the imidazole makes it a common participant in enzyme catalyzed reactions. The unprotonated imidazole which is nucleophilic can serve as a general base, while the protonated form can serve as a general acid.