521. An essential amino acid is one that
A. is essentially easy to synthesize
B. is essential to flagella motion
C. the body cannot synthesize
D. the body can synthesize under essential conditions
522 .D-Alanine and L-Alanine are technically known as
A. anomers
B. enantiomers
C. epimers
D. polymer
523. Which of the following pairs of amino acids would carry a negative charge on their side chain at pH 8.0?
A. Asparagine & Glutamine
B. Leucine & Glycine
C. Histidine & Lysine
D. Aspartate & Glutamate
524. In a polypeptide average mass of an amino acid residue is
A. 110 daltons
B. 118 daltons
C. 80 daltons
D. 150 daltons
525. Which pair of amino acids absorbs the most UV light at 280 nm?
A. Threonine & Histidine
B. Trp& Tyrosine
C. Cystein& Asparagine
D. Phenylalnine& Proline
526. Which of the following is a nonstandard amino acid?
A. Cysteine
B. Isoleucine
C. Hydroxyproline
D. Histidine
527. Which of the following is an essential amino acid?
A. Tryptophan
B. Methionine
C. Lysine
D. All of these
528. Protein fluorescence arises primarily from which residue?
A. Arginine
B. Tryptophan
C. Tyrosine
D. Phenylalanine
529. Which of the following amino acid is known as half-cystine residue?
A. Cysteine
B. Isoleucine
C. Valine
D. Histidine
530. Which of the following is not an essential amino acid?
A. Aspartic acid
B. Glutamic acid
C. Glycine
D. All of these