BIOCHEMISTRY CONCEPTS AND
CONNECTIONS 2026 ENZYMOLOGY AND
METABOLIC PATHWAYS ASSESSMENT STUDY
GUIDE COMPLETE QUESTIONS AND ANSWERS
◉ Proline is distinct among the 20 commonly found amino acids
because ________.
It is hydrophilic and ionic
It is a ring compound
The nitrogen of the amino group is cyclized in a ring
The carbon of the carboxyl group is cyclized in a ring
The nitrogen of the amino group is cyclized in a ring. Answer: The
nitrogen of the amino group is cyclized in a ring
◉ Alanine, valine, leucine and isoleucine are important in three
dimensional structure because they ________.
Are highly hydrophobic
Are branched
Attract water molecules
Are highly hydrophilic. Answer: Are highly hydrophobic
,◉ Ultraviolet (UV) light can be used to estimate protein solution
concentrations because ________.
Phenylalanine absorbs at 260 nm
All the amino acids absorb UV light
Aromatic amino acids absorb at 280 nm
Tryptophan and tyrosine absorb at 280 nm. Answer: Tryptophan
and tyrosine absorb at 280 nm
◉ The amino acids in polypeptide chains which contain sulfur (S)
are ________.
Cysteine
Cysteine, lysine, and methionine
Methionine only
Cysteine and methionine. Answer: Cysteine and methionine
◉ Basic amino acids are ________ (positive, negative) at pH 7 and
acidic R group amino acids are ________ (positive, negative) at pH 7.
Negative; positive
Positive; negative
Negative; negative
Positive; positive. Answer: Positive; negative
, ◉ Arginine is the most basic of the 20 amino acids because its side
chain is ________ under most cell conditions.
Titrated
Hydrophobic
Protonated
Very highly charged. Answer: Protonated
◉ At the isoelectric pH of an amino acid which has two pKa values
the net charge is ________.
0
0.5
-1
1. Answer: 0
◉ Histidine has pKa values of 1.8, 6.0 (R-group) and 9.3. At pH 8.0,
the net charge on histidine is ________.
Positive
Negative
Neutral (uncharged)
Insufficient information to tell. Answer: Neutral (uncharged)
CONNECTIONS 2026 ENZYMOLOGY AND
METABOLIC PATHWAYS ASSESSMENT STUDY
GUIDE COMPLETE QUESTIONS AND ANSWERS
◉ Proline is distinct among the 20 commonly found amino acids
because ________.
It is hydrophilic and ionic
It is a ring compound
The nitrogen of the amino group is cyclized in a ring
The carbon of the carboxyl group is cyclized in a ring
The nitrogen of the amino group is cyclized in a ring. Answer: The
nitrogen of the amino group is cyclized in a ring
◉ Alanine, valine, leucine and isoleucine are important in three
dimensional structure because they ________.
Are highly hydrophobic
Are branched
Attract water molecules
Are highly hydrophilic. Answer: Are highly hydrophobic
,◉ Ultraviolet (UV) light can be used to estimate protein solution
concentrations because ________.
Phenylalanine absorbs at 260 nm
All the amino acids absorb UV light
Aromatic amino acids absorb at 280 nm
Tryptophan and tyrosine absorb at 280 nm. Answer: Tryptophan
and tyrosine absorb at 280 nm
◉ The amino acids in polypeptide chains which contain sulfur (S)
are ________.
Cysteine
Cysteine, lysine, and methionine
Methionine only
Cysteine and methionine. Answer: Cysteine and methionine
◉ Basic amino acids are ________ (positive, negative) at pH 7 and
acidic R group amino acids are ________ (positive, negative) at pH 7.
Negative; positive
Positive; negative
Negative; negative
Positive; positive. Answer: Positive; negative
, ◉ Arginine is the most basic of the 20 amino acids because its side
chain is ________ under most cell conditions.
Titrated
Hydrophobic
Protonated
Very highly charged. Answer: Protonated
◉ At the isoelectric pH of an amino acid which has two pKa values
the net charge is ________.
0
0.5
-1
1. Answer: 0
◉ Histidine has pKa values of 1.8, 6.0 (R-group) and 9.3. At pH 8.0,
the net charge on histidine is ________.
Positive
Negative
Neutral (uncharged)
Insufficient information to tell. Answer: Neutral (uncharged)
