BIOC 3022 Exam 4 Newest 2026 Questions and
Correct Detailed Detailed Answers Already Graded A+
What does AMPK do to ACC? - CORRECT ANSWER-AMPK phosphorylates ACC,
making it inactive
What effect does insulin have on ACC? - CORRECT ANSWER-Insulin promotes
dephosphorylation of ACC, activating it (high energy/fed state signal)
Under low energy charge, how is fatty acid synthesis inhibited? - CORRECT
ANSWER-AMPK phosphorylates ACC, blocking malonyl-CoA production
How does high malonyl-CoA simultaneously inhibit fatty acid oxidation? -
CORRECT ANSWER-Malonyl-CoA inhibits CPT I (carnitine palmitoyl-transferase
I), blocking fatty acyl-CoA entry into the mitochondria for β-oxidation
What is the physiological significance of citrate inhibiting PFK1? - CORRECT
ANSWER-When energy is sufficient (high citrate), the cell signals glycolysis to
slow down, diverting carbon toward fat storage instead
,What four molecules are key to the shuttle system that moves substrates across
the mitochondrial membrane for fatty acid synthesis? - CORRECT ANSWER-
Citrate, pyruvate, malate, and fatty acyl-carnitine
What enzyme cleaves citrate in the cytoplasm during fatty acid synthesis? -
CORRECT ANSWER-ATP-Citrate Lyase
What two molecules are produced when ATP-Citrate Lyase cleaves citrate? -
CORRECT ANSWER-Oxaloacetate and acetyl-CoA
What is the first committed step of fatty acid synthesis? - CORRECT ANSWER-
Carboxylation of acetyl-CoA to form malonyl-CoA by acetyl-CoA carboxylase (ACC)
What cofactors/energy does the ACC reaction require? - CORRECT ANSWER-
ATP and biotin
What is the role of Fatty Acid Synthase (FAS)? - CORRECT ANSWER-It is a multi-
enzyme protein complex that catalyzes the addition of two-carbon units to a
growing acyl chain
,How does chain extension occur in FAS? - CORRECT ANSWER-Malonyl-CoA is
decarboxylated, and the resulting two-carbon fragment is added to the growing
chain
What is the final product of FAS-mediated chain extension? - CORRECT
ANSWER-Palmitic acid (16 carbons)
What happens if a fatty acid longer than 16 carbons or with double bonds is
needed? - CORRECT ANSWER-Other enzymes (elongases and desaturases) add
further carbons and double bonds
What metabolic condition triggers the initiation of fatty acid synthesis? -
CORRECT ANSWER-A high energy charge, causing NADH accumulation
What happens to citrate when the energy charge is high? - CORRECT ANSWER-
Citrate accumulates in the TCA cycle and is transported to the cytosol
Why does citrate accumulate when glycolysis is high? - CORRECT ANSWER-
Excess acetyl-CoA enters the TCA cycle; when NADH builds up and slows the cycle,
citrate backs up and is exported
, How does citrate cross the inner mitochondrial membrane? - CORRECT
ANSWER-Via the citrate transport protein (a specific carrier)
How does citrate cross the outer mitochondrial membrane? - CORRECT
ANSWER-By free diffusion
What does ATP-citrate lyase do to citrate in the cytosol? - CORRECT ANSWER-
It cleaves citrate into acetyl-CoA and oxaloacetate, consuming ATP
What happens to oxaloacetate (OAA) after citrate is cleaved in the cytosol? -
CORRECT ANSWER-OAA is reduced to malate by malate dehydrogenase, using
NADH
What enzyme converts malate to pyruvate in the cytosol? - CORRECT
ANSWER-Malate enzyme (malic enzyme)
What cofactor does malic enzyme require, and what is produced? - CORRECT
ANSWER-It requires NADP⁺ and produces NADPH and CO₂
Correct Detailed Detailed Answers Already Graded A+
What does AMPK do to ACC? - CORRECT ANSWER-AMPK phosphorylates ACC,
making it inactive
What effect does insulin have on ACC? - CORRECT ANSWER-Insulin promotes
dephosphorylation of ACC, activating it (high energy/fed state signal)
Under low energy charge, how is fatty acid synthesis inhibited? - CORRECT
ANSWER-AMPK phosphorylates ACC, blocking malonyl-CoA production
How does high malonyl-CoA simultaneously inhibit fatty acid oxidation? -
CORRECT ANSWER-Malonyl-CoA inhibits CPT I (carnitine palmitoyl-transferase
I), blocking fatty acyl-CoA entry into the mitochondria for β-oxidation
What is the physiological significance of citrate inhibiting PFK1? - CORRECT
ANSWER-When energy is sufficient (high citrate), the cell signals glycolysis to
slow down, diverting carbon toward fat storage instead
,What four molecules are key to the shuttle system that moves substrates across
the mitochondrial membrane for fatty acid synthesis? - CORRECT ANSWER-
Citrate, pyruvate, malate, and fatty acyl-carnitine
What enzyme cleaves citrate in the cytoplasm during fatty acid synthesis? -
CORRECT ANSWER-ATP-Citrate Lyase
What two molecules are produced when ATP-Citrate Lyase cleaves citrate? -
CORRECT ANSWER-Oxaloacetate and acetyl-CoA
What is the first committed step of fatty acid synthesis? - CORRECT ANSWER-
Carboxylation of acetyl-CoA to form malonyl-CoA by acetyl-CoA carboxylase (ACC)
What cofactors/energy does the ACC reaction require? - CORRECT ANSWER-
ATP and biotin
What is the role of Fatty Acid Synthase (FAS)? - CORRECT ANSWER-It is a multi-
enzyme protein complex that catalyzes the addition of two-carbon units to a
growing acyl chain
,How does chain extension occur in FAS? - CORRECT ANSWER-Malonyl-CoA is
decarboxylated, and the resulting two-carbon fragment is added to the growing
chain
What is the final product of FAS-mediated chain extension? - CORRECT
ANSWER-Palmitic acid (16 carbons)
What happens if a fatty acid longer than 16 carbons or with double bonds is
needed? - CORRECT ANSWER-Other enzymes (elongases and desaturases) add
further carbons and double bonds
What metabolic condition triggers the initiation of fatty acid synthesis? -
CORRECT ANSWER-A high energy charge, causing NADH accumulation
What happens to citrate when the energy charge is high? - CORRECT ANSWER-
Citrate accumulates in the TCA cycle and is transported to the cytosol
Why does citrate accumulate when glycolysis is high? - CORRECT ANSWER-
Excess acetyl-CoA enters the TCA cycle; when NADH builds up and slows the cycle,
citrate backs up and is exported
, How does citrate cross the inner mitochondrial membrane? - CORRECT
ANSWER-Via the citrate transport protein (a specific carrier)
How does citrate cross the outer mitochondrial membrane? - CORRECT
ANSWER-By free diffusion
What does ATP-citrate lyase do to citrate in the cytosol? - CORRECT ANSWER-
It cleaves citrate into acetyl-CoA and oxaloacetate, consuming ATP
What happens to oxaloacetate (OAA) after citrate is cleaved in the cytosol? -
CORRECT ANSWER-OAA is reduced to malate by malate dehydrogenase, using
NADH
What enzyme converts malate to pyruvate in the cytosol? - CORRECT
ANSWER-Malate enzyme (malic enzyme)
What cofactor does malic enzyme require, and what is produced? - CORRECT
ANSWER-It requires NADP⁺ and produces NADPH and CO₂
