LEHNINGERS PRINCIPLES OF BIOCHEMISTRY
CHAPTER 15 QUESTIONS WITH CORRECT
ANSWERS
Glycogen is converted to monosaccharide units by:
A) glucokinase.
B) glucose-6-phosphatase
C) glycogen phosphorylase.
D) glycogen synthase.
E) glycogenase. CORRECT ANSWER C) glycogen phosphorylase.
The glycogen-branching enzyme catalyzes:
A) degradation of (α1 → 4) linkages in glycogen
B) formation of (α1 → 4) linkages in glycogen.
C) formation of (α1 → 6) linkages during glycogen synthesis.
D) glycogen degradation in tree branches.
E) removal of unneeded glucose residues at the ends of branches. CORRECT ANSWER C)
formation of (α1 → 6) linkages during glycogen synthesis.
Glycogenin:
A) catalyzes the conversion of starch into glycogen.
B) is the enzyme responsible for forming branches in glycogen.
C) is the gene that encodes glycogen synthase.
D) is the primer on which new glycogen chains are initiated.
, E) regulates the synthesis of glycogen. CORRECT ANSWER D) is the primer on which new
glycogen chains are initiated.
Which of the following is true of glycogen synthase?
A) Activation of the enzyme involves a phosphorylation.
B) It catalyzes addition of glucose residues to the nonreducing end of a glycogen chain by
formation
of (α1 → 4) bonds.
C) It uses glucose-6-phosphate as donor of glucose units
D) The conversion of an active to an inactive form of the enzyme is controlled by the
concentration
of cAMP.
E) The enzyme has measurable activity only in liver. CORRECT ANSWER B) It catalyzes addition
of glucose residues to the nonreducing end of a glycogen chain by formation
of (α1 → 4) bonds.
Which one of the following statements about mammalian glycogen synthase is not correct?
A) It is especially predominant in liver and muscle.
B) The donor molecule is a sugar nucleotide.
C) The phosphorylated form of this enzyme is inactive.
D) This enzyme adds glucose units to the nonreducing end of glycogen branches.
E) This enzyme adds the initial glucose unit to a tyrosine residue in glycogenin. CORRECT
ANSWER E) This enzyme adds the initial glucose unit to a tyrosine residue in glycogenin.
The enzyme glycogen phosphorylase:
A) catalyzes a cleavage of β (1 → 4) bonds.
CHAPTER 15 QUESTIONS WITH CORRECT
ANSWERS
Glycogen is converted to monosaccharide units by:
A) glucokinase.
B) glucose-6-phosphatase
C) glycogen phosphorylase.
D) glycogen synthase.
E) glycogenase. CORRECT ANSWER C) glycogen phosphorylase.
The glycogen-branching enzyme catalyzes:
A) degradation of (α1 → 4) linkages in glycogen
B) formation of (α1 → 4) linkages in glycogen.
C) formation of (α1 → 6) linkages during glycogen synthesis.
D) glycogen degradation in tree branches.
E) removal of unneeded glucose residues at the ends of branches. CORRECT ANSWER C)
formation of (α1 → 6) linkages during glycogen synthesis.
Glycogenin:
A) catalyzes the conversion of starch into glycogen.
B) is the enzyme responsible for forming branches in glycogen.
C) is the gene that encodes glycogen synthase.
D) is the primer on which new glycogen chains are initiated.
, E) regulates the synthesis of glycogen. CORRECT ANSWER D) is the primer on which new
glycogen chains are initiated.
Which of the following is true of glycogen synthase?
A) Activation of the enzyme involves a phosphorylation.
B) It catalyzes addition of glucose residues to the nonreducing end of a glycogen chain by
formation
of (α1 → 4) bonds.
C) It uses glucose-6-phosphate as donor of glucose units
D) The conversion of an active to an inactive form of the enzyme is controlled by the
concentration
of cAMP.
E) The enzyme has measurable activity only in liver. CORRECT ANSWER B) It catalyzes addition
of glucose residues to the nonreducing end of a glycogen chain by formation
of (α1 → 4) bonds.
Which one of the following statements about mammalian glycogen synthase is not correct?
A) It is especially predominant in liver and muscle.
B) The donor molecule is a sugar nucleotide.
C) The phosphorylated form of this enzyme is inactive.
D) This enzyme adds glucose units to the nonreducing end of glycogen branches.
E) This enzyme adds the initial glucose unit to a tyrosine residue in glycogenin. CORRECT
ANSWER E) This enzyme adds the initial glucose unit to a tyrosine residue in glycogenin.
The enzyme glycogen phosphorylase:
A) catalyzes a cleavage of β (1 → 4) bonds.
