PHA 339 - Dr. Hafez HIGH YIELD QUIZLET

What metabolic pathway produces ketone bodies during prolonged fasting?

Ketogenesis

What molecule produced from beta-oxidation can be used to generate ketone bodies?

Acetyl-CoA

What tissues commonly use ketone bodies for energy during fasting?

Brain and skeletal muscle

Why can red blood cells not utilize ketone bodies?

They lack mitochondria

What are the three irreversible steps of glycolysis?

Hexokinase, PFK-1, Pyruvate kinase

What is the rate-limiting enzyme of glycolysis?

PFK-1

What molecule inhibits PFK-1 and glycolysis?

ATP

What molecule strongly activates PFK-1?

Fructose-2,6-bisphosphate

What enzyme converts glucose to glucose-6-phosphate?

Hexokinase

Why is glucose converted to glucose-6-phosphate?

To trap glucose inside the cell and commit it to glycolysis

What enzyme converts fructose-6-phosphate to fructose-1,6-bisphosphate?

PFK-1

What enzyme converts PEP to pyruvate?

Pyruvate kinase

What metabolic pathway converts glucose into pyruvate?

Glycolysis

What is the end product of aerobic glycolysis?

Pyruvate

What is the end product of anaerobic glycolysis?

Lactate

What are the two possible fates of pyruvate?

Acetyl-CoA (aerobic) or lactate (anaerobic)

What enzyme converts pyruvate to acetyl-CoA?

Pyruvate dehydrogenase

What happens when pyruvate dehydrogenase is deficient?

Lactate accumulation and lactic acidosis

What is the main substrate entering the TCA cycle?

Acetyl-CoA

Where does the TCA cycle occur?

Mitochondrial matrix

What reaction does isocitrate dehydrogenase catalyze?

Isocitrate → alpha-ketoglutarate producing NADH

What metabolic pathway produces NADH and FADH2 for the electron transport chain?

TCA (Krebs) cycle

What is the purpose of the electron transport chain?

Use NADH and FADH2 to generate ATP

Where is the electron transport chain located?

Inner mitochondrial membrane

What are the two major electron carriers feeding the ETC?

NADH and FADH2

Oxidation of one NADH in the ETC produces approximately how much ATP?

3 ATP

What is the name of ETC Complex II?

Succinate dehydrogenase

Complex II transfers electrons from what molecule to CoQ?

FADH2

What is the function of CoQ in the ETC?

Transfers electrons from complexes I and II to complex III

What is cytochrome c?

A mobile electron carrier between complexes III and IV

What enzyme converts pyruvate to oxaloacetate in gluconeogenesis?

Pyruvate carboxylase

What are the main gluconeogenic precursors?

Lactate, glycerol, glucogenic amino acids

What is the key regulatory enzyme of gluconeogenesis?

Fructose-1,6-bisphosphatase

What hormone stimulates gluconeogenesis?

Glucagon

What hormone inhibits gluconeogenesis and stimulates glycolysis?

Insulin

What metabolic pathway produces glucose during fasting?

Gluconeogenesis

What are the main products of lipolysis?

Free fatty acids and glycerol

What metabolic process breaks down triglycerides to release fatty acids and glycerol?

Lipolysis

What metabolic process breaks down fatty acids for energy?

Beta-oxidation

How do long-chain fatty acids enter mitochondria?

Carnitine shuttle

Each cycle of beta-oxidation produces what molecules?

1 acetyl-CoA, 1 NADH, 1 FADH2

What molecule produced from beta-oxidation can generate ketone bodies?

Acetyl-CoA

What metabolic pathway produces ketone bodies during prolonged fasting?

Ketogenesis

Which organ produces ketone bodies?

Liver

Which organ produces ketone bodies but cannot use them?

Liver

Which tissues use ketone bodies for energy?

Brain and skeletal muscle

Why can't RBCs use ketone bodies?

They lack mitochondria

Why can RBCs only perform glycolysis?

They lack mitochondria so they cannot run the TCA cycle or ETC

What metabolic pathways are active in the fed state?

Glycolysis, glycogenesis, fatty acid synthesis

What metabolic pathways are active during fasting or starvation?

Gluconeogenesis, lipolysis, ketogenesis

In catabolism, fats are degraded into what products?

Fatty acids and glycerol

In catabolism, proteins are degraded into what products?

Amino acids

In catabolism, fatty acids are converted into what molecule?

Acetyl-CoA

Acetyl-CoA is utilized to do what?

Generate ATP through the TCA cycle and ETC

What is the first stage of catabolism?

Hydrolysis of complex molecules

What two processes occur during catabolism?

Hydrolysis of complex molecules and generation of ATP

Where does glycolysis occur?

Cytosol

Where does gluconeogenesis occur?

Mitochondria and cytosol

Where does beta-oxidation occur?

Mitochondrial matrix

Where does fatty acid synthesis occur?

Cytosol

Where does lipolysis occur?

Cytosol

What molecule connects carbohydrate, fat, and protein metabolism?

Acetyl-CoA

What molecule links glycolysis to the TCA cycle?

Acetyl-CoA

What molecule is produced at the end of glycolysis that can enter multiple pathways?

Pyruvate

What metabolic pathway generates the majority of ATP in cells?

Electron transport chain

What happens to glycerol released from triglycerides during lipolysis?

It enters gluconeogenesis to produce glucose

What is the overall metabolic pathway from glucose to ATP?

Glucose → Glycolysis → Pyruvate → Acetyl-CoA → TCA cycle → NADH/FADH2 → Electron transport chain → ATP

What pathway converts glucose to pyruvate?

Glycolysis

What molecule connects glycolysis to the TCA cycle?

Acetyl-CoA

What metabolic pathway produces NADH and FADH2 from acetyl-CoA?

TCA (Krebs) cycle

What metabolic pathway uses NADH and FADH2 to generate ATP?

Electron transport chain

What metabolic pathway breaks down triglycerides into fatty acids and glycerol?

Lipolysis

What metabolic pathway converts fatty acids into acetyl-CoA?

Beta-oxidation

What molecule produced from beta-oxidation enters the TCA cycle?

Acetyl-CoA

What metabolic pathway produces ketone bodies during prolonged fasting?

Ketogenesis

What metabolic pathway allows fats to contribute to ATP production?

Lipolysis → Beta-oxidation → Acetyl-CoA → TCA cycle → ETC