Name _____________________________
UIN ___________________
Biochemistry 411
Quiz 3
1.) (2 Points) What is the overall reaction of gluconeogenesis?
Glucose + 4 ADP + 2 GDP + 2 NAD+ + 6Pi
Answer: 2 Pyruvate + 4 ATP + 2 GTP + 2NADH
2.) (4 Points) Gluconeogenesis is not simply the reverse of glycolysis. There are three
irreversible steps of glycolysis that must be bypassed in order for gluconeogenesis to occur.
The enzymes that catalyze the irreversible steps in glycolysis are shown below. For each of
these steps, list the enzyme(s) that are used in gluconeogenesis to drive the formation of
glucose from pyruvate.
Glycolysis:
(a.) Hexokinase
(b.) Phosphofructokinase
(c.) Pyruvate Kinase
Gluconeogenesis:
(a.) ______________________________
(b.) ______________________________
(c.) ______________________________
______________________________
Answer (a.) Glucose-6-Phosphatase
(b.) Fructose-1,6-bisphosphatase
(c.) Pyruvate Carboxylase and PEP Carboxykinase
3.) (4 Points) Pyruvate Carboxylase has two active sites. Draw the mechanism for the reaction
that occurs in the second active site:
Pyruvate + CO2
Oxaloacetate
(Hint: The enzyme Pyruvate Carboxylase uses the cofactor biotin)
O
CO2
O
N
NH
H
O
Enz
S
O
O
C
O
C
H
H
Pyruvate
CO2
CO2
N
NH
NH
+
S
Enz
S
Biotin
NH
+
C
H
C
Enz
H
O
O
C
O
C
O
CH2
CO2
Oxaloacetate