BCH 367 EXAM 3 QUESTIONS AND
ANSWERS (GRADED A+)
What is the main purpose of gluconeogenesis? - ANSWER-Pyruvate -> Glucose
Where does gluconeogenesis occiur? - ANSWER-Liver
When does gluconeogenesis occur? - ANSWER-During starvation
What is the main purpose of the Cori Cycle? - ANSWER-Lactate to Pyruvate, then
gluconeogenesis
Is gluconeogenesis the reverse of glycolysis? - ANSWER-no, has some shared
pathways but the three irreversible steps in glycolysis must be bypassed in
gluconeogenesis
How does pyruvate exit the mitochondria during gluconeogenesis? - ANSWER-It must
become oxaloacetate, then malate to pass through the membrane and return back to
oxaloacetate
What are the enzymes that replace the irreversible glycolysis steps during
gluconeogenesis? Where does the process occur? - ANSWER-1. Hexokinase ->
Glucose 6-phosphatase (in the ER)
3. PFK -> Fructose 1,6-biphosphotase (in the cytoplasm)
10. Pyruvate Kinase -> Pyruvate carboxylase (in the mitochondria) and PEP
carboxylkinase (in the cytoplasm)
What occurs when blood glucose is low? - ANSWER-Glucagon is secreted
What occurs when blood glucose is high? - ANSWER-There is low glucagon
What is glucagon? - ANSWER-Hormone that stimulates glucose production
Requirements for gluconeogensis to occur? - ANSWER-Six high transfer-potential
phosphoryl groups (i.e. ATP or GTP)
PDH enzymes - ANSWER-E1: Decarboxylation
E1/E2: Oxidation
E2: Transfer to CoA
E3: Regenerates lipoamide, which is involved in second step(E1/E2)
Important characteristics of Thiamine pyrophosphate (TPP) - ANSWER-Has a nitrogen
to stabilize the carbanion form which makes it a good nucleophile to attack pyruvate
, What complex makes Acetyl CoA from pyruvate? - ANSWER-Pyruvate dehydrogenase
complex (PDH)
Under what conditions does pyruvate enter the mitochondria? - ANSWER-Aerobic
What is the Warburg effect? - ANSWER-Even in the presence of oxygen, cancer cell
preferentially undergo Glycolysis/Lactic acid fermentation over more energy efficient
mitochondrial oxidative phosphorylation pathways.
Non-covalent Regulation of PDH: What inhibits the PDH complex? - ANSWER-
Allosterically- Acetyl CoA and NADH
Indirectly- High ATP, acetyl CoA and NADH
Non-covalent Regulation of PDH: What activates the PDH complex? - ANSWER-ADP,
pyruvate, Ca2+ and Insulin
Mechanism of Mercury and Arsenic poisoning - ANSWER-Binds to the two sulfurs of
dihydrolipoamide (E2 in PDH)
What does a thiamine deficiency cause? - ANSWER-Beriberi: Insufficient TPP and
reduced pyruvatedehydrogenase (E1 in PDH) activity
Outputs of Citric Acid Cycle - ANSWER-3 NADH and 1 FADH2 (8 high energy e-)
What two components make citrate? - ANSWER-Acetyl-CoA and oxaloacetate
What is the glyoxylate cycle? - ANSWER-in plants and bacteria, allowing the synthesis
of carbohydrates from fats
Stage 1 of CAC: C number and molecules - ANSWER-2C (an acetyl group) are
condensed with a 4C Oxaloacetate to form the 6C Citrate which will undergo two
oxidative decarboxylations, generating 2 CO2
Stage 2 of CAC: C number and molecules - ANSWER-Oxaloacetate is regenerated
What 2 processes make up cellular respiration? - ANSWER-Citric acid cycle and
oxidative phosphorylation
Characteristics of mitochondrial membranes - ANSWER-Inner: Impermeable
Outer: Permeanble
What is the final e- acceptor? - ANSWER-O2
What ETC complex does NOT pump protons? - ANSWER-Complex II
ANSWERS (GRADED A+)
What is the main purpose of gluconeogenesis? - ANSWER-Pyruvate -> Glucose
Where does gluconeogenesis occiur? - ANSWER-Liver
When does gluconeogenesis occur? - ANSWER-During starvation
What is the main purpose of the Cori Cycle? - ANSWER-Lactate to Pyruvate, then
gluconeogenesis
Is gluconeogenesis the reverse of glycolysis? - ANSWER-no, has some shared
pathways but the three irreversible steps in glycolysis must be bypassed in
gluconeogenesis
How does pyruvate exit the mitochondria during gluconeogenesis? - ANSWER-It must
become oxaloacetate, then malate to pass through the membrane and return back to
oxaloacetate
What are the enzymes that replace the irreversible glycolysis steps during
gluconeogenesis? Where does the process occur? - ANSWER-1. Hexokinase ->
Glucose 6-phosphatase (in the ER)
3. PFK -> Fructose 1,6-biphosphotase (in the cytoplasm)
10. Pyruvate Kinase -> Pyruvate carboxylase (in the mitochondria) and PEP
carboxylkinase (in the cytoplasm)
What occurs when blood glucose is low? - ANSWER-Glucagon is secreted
What occurs when blood glucose is high? - ANSWER-There is low glucagon
What is glucagon? - ANSWER-Hormone that stimulates glucose production
Requirements for gluconeogensis to occur? - ANSWER-Six high transfer-potential
phosphoryl groups (i.e. ATP or GTP)
PDH enzymes - ANSWER-E1: Decarboxylation
E1/E2: Oxidation
E2: Transfer to CoA
E3: Regenerates lipoamide, which is involved in second step(E1/E2)
Important characteristics of Thiamine pyrophosphate (TPP) - ANSWER-Has a nitrogen
to stabilize the carbanion form which makes it a good nucleophile to attack pyruvate
, What complex makes Acetyl CoA from pyruvate? - ANSWER-Pyruvate dehydrogenase
complex (PDH)
Under what conditions does pyruvate enter the mitochondria? - ANSWER-Aerobic
What is the Warburg effect? - ANSWER-Even in the presence of oxygen, cancer cell
preferentially undergo Glycolysis/Lactic acid fermentation over more energy efficient
mitochondrial oxidative phosphorylation pathways.
Non-covalent Regulation of PDH: What inhibits the PDH complex? - ANSWER-
Allosterically- Acetyl CoA and NADH
Indirectly- High ATP, acetyl CoA and NADH
Non-covalent Regulation of PDH: What activates the PDH complex? - ANSWER-ADP,
pyruvate, Ca2+ and Insulin
Mechanism of Mercury and Arsenic poisoning - ANSWER-Binds to the two sulfurs of
dihydrolipoamide (E2 in PDH)
What does a thiamine deficiency cause? - ANSWER-Beriberi: Insufficient TPP and
reduced pyruvatedehydrogenase (E1 in PDH) activity
Outputs of Citric Acid Cycle - ANSWER-3 NADH and 1 FADH2 (8 high energy e-)
What two components make citrate? - ANSWER-Acetyl-CoA and oxaloacetate
What is the glyoxylate cycle? - ANSWER-in plants and bacteria, allowing the synthesis
of carbohydrates from fats
Stage 1 of CAC: C number and molecules - ANSWER-2C (an acetyl group) are
condensed with a 4C Oxaloacetate to form the 6C Citrate which will undergo two
oxidative decarboxylations, generating 2 CO2
Stage 2 of CAC: C number and molecules - ANSWER-Oxaloacetate is regenerated
What 2 processes make up cellular respiration? - ANSWER-Citric acid cycle and
oxidative phosphorylation
Characteristics of mitochondrial membranes - ANSWER-Inner: Impermeable
Outer: Permeanble
What is the final e- acceptor? - ANSWER-O2
What ETC complex does NOT pump protons? - ANSWER-Complex II
