BMB 1203 MEDICAL BIOCHEMISTRY II: VERIFIED ANSWERS
AND QUESTIONS - MOST RECENT EDITION 2026/2027 (PASS
GUARANTEE)
Q: Where does the Electron Transport Chain (ETC) occur? ANSWER In the
inner mitochondrial membrane.
Q: What are the four protein complexes in the ETC? ANSWER Complex I
(NADH dehydrogenase), Complex II (Succinate dehydrogenase), Complex III
(Cytochrome bc1), and Complex IV (Cytochrome c oxidase).
Q: What are the two mobile electron carriers in the ETC? ANSWER Ubiquinone
(Coenzyme Q) and Cytochrome c.
Q: What is the final electron acceptor in the ETC? ANSWER Molecular oxygen
(O2).
Q: What is formed when oxygen accepts electrons? ANSWER Water (H2O).
Q: How many protons does Complex I pump across the membrane? ANSWER
4 protons.
Q: How many protons does Complex III pump across the membrane? ANSWER
4 protons.
Q: How many protons does Complex IV pump across the membrane? ANSWER
2 protons.
Q: Does Complex II pump protons? ANSWER No, it only passes electrons to
ubiquinone.
Q: What is the proton motive force? ANSWER The electrochemical gradient
created by the pumping of protons across the inner mitochondrial membrane.
Q: What is ATP synthase also known as? ANSWER Complex V.
Q: Approximately how many ATP are produced per NADH oxidized? ANSWER
2.5 ATP.
,Q: Approximately how many ATP are produced per FADH2 oxidized? ANSWER
1.5 ATP.
Q: What is chemiosmotic coupling? ANSWER The process where the energy
from the proton gradient is used by ATP synthase to phosphorylate ADP to
ATP.
Q: What is an uncoupler? ANSWER A molecule that disrupts the proton
gradient, allowing protons to flow back without producing ATP (e.g., DNP).
Q: What happens to energy in the presence of an uncoupler? ANSWER It is
released as heat instead of being used to make ATP.
Q: What is the physiological uncoupling protein in brown adipose tissue?
ANSWER Thermogenin (UCP1).
Q: What are Reactive Oxygen Species (ROS)? ANSWER Highly reactive
molecules derived from incomplete reduction of oxygen (e.g., superoxide
anion).
Q: Which complexes primarily leak electrons to form ROS? ANSWER Complex I
and Complex III.
Q: What enzyme converts superoxide to hydrogen peroxide? ANSWER
Superoxide dismutase (SOD).
Q: How is hydrogen peroxide detoxified in the cell? ANSWER By catalase or
glutathione peroxidase.
Q: What is the P/O ratio? ANSWER The number of ATP molecules produced
per oxygen atom (1/2 O2) reduced.
Q: What inhibitor blocks electron flow at Complex I? ANSWER Rotenone.
Q: What inhibitor blocks electron flow at Complex III? ANSWER Antimycin A.
Q: What inhibitors block electron flow at Complex IV? ANSWER Cyanide,
carbon monoxide (CO), and azide.
Q: What inhibitor blocks ATP synthase directly? ANSWER Oligomycin.
Q: Why can't cytosolic NADH enter the mitochondria directly? ANSWER The
inner mitochondrial membrane is impermeable to NADH.
Q: What are the two main shuttles for cytosolic NADH? ANSWER The malate-
aspartate shuttle and the glycerol-3-phosphate shuttle.
, Q: Which shuttle yields more ATP and where is it found? ANSWER The malate-
aspartate shuttle (yields ~2.5 ATP), found in liver and kidney.
Q: What does the glycerol-3-phosphate shuttle yield and where is it found?
ANSWER Yields ~1.5 ATP (transfers electrons to FADH2), found in brain and
skeletal muscle.
Q: What is the total theoretical ATP yield from one molecule of glucose?
ANSWER Approximately 30-32 ATP.
Q: Where is ubiquinone located in the membrane? ANSWER It is deeply
embedded within the lipid bilayer of the inner mitochondrial membrane.
Q: Where is cytochrome c located? ANSWER Loosely attached to the outer
surface of the inner mitochondrial membrane.
Q: What metal ion is at the active center of cytochromes? ANSWER Iron (Fe).
Q: What metal ions are found in Complex IV? ANSWER Iron (heme) and copper
(Cu).
Section 2: Lipid Metabolism & Fatty Acid Oxidation (36-70)
Q: What are the three major types of dietary lipids? ANSWER Triglycerides,
phospholipids, and cholesterol.
Q: What enzyme digests dietary triglycerides in the small intestine? ANSWER
Pancreatic lipase.
Q: What is the role of bile salts in digestion? ANSWER They emulsify lipids,
increasing their surface area for lipase action.
Q: How are dietary fatty acids absorbed into intestinal cells? ANSWER As
mixed micelles.
Q: How are dietary lipids packaged for transport in the blood? ANSWER As
chylomicrons.
Q: Where does beta-oxidation of fatty acids occur? ANSWER In the
mitochondrial matrix.
Q: How are activated fatty acids transported into the mitochondria? ANSWER
Via the carnitine shuttle.
Q: What enzyme attaches carnitine to the fatty acid? ANSWER Carnitine
palmitoyltransferase I (CPT I).
AND QUESTIONS - MOST RECENT EDITION 2026/2027 (PASS
GUARANTEE)
Q: Where does the Electron Transport Chain (ETC) occur? ANSWER In the
inner mitochondrial membrane.
Q: What are the four protein complexes in the ETC? ANSWER Complex I
(NADH dehydrogenase), Complex II (Succinate dehydrogenase), Complex III
(Cytochrome bc1), and Complex IV (Cytochrome c oxidase).
Q: What are the two mobile electron carriers in the ETC? ANSWER Ubiquinone
(Coenzyme Q) and Cytochrome c.
Q: What is the final electron acceptor in the ETC? ANSWER Molecular oxygen
(O2).
Q: What is formed when oxygen accepts electrons? ANSWER Water (H2O).
Q: How many protons does Complex I pump across the membrane? ANSWER
4 protons.
Q: How many protons does Complex III pump across the membrane? ANSWER
4 protons.
Q: How many protons does Complex IV pump across the membrane? ANSWER
2 protons.
Q: Does Complex II pump protons? ANSWER No, it only passes electrons to
ubiquinone.
Q: What is the proton motive force? ANSWER The electrochemical gradient
created by the pumping of protons across the inner mitochondrial membrane.
Q: What is ATP synthase also known as? ANSWER Complex V.
Q: Approximately how many ATP are produced per NADH oxidized? ANSWER
2.5 ATP.
,Q: Approximately how many ATP are produced per FADH2 oxidized? ANSWER
1.5 ATP.
Q: What is chemiosmotic coupling? ANSWER The process where the energy
from the proton gradient is used by ATP synthase to phosphorylate ADP to
ATP.
Q: What is an uncoupler? ANSWER A molecule that disrupts the proton
gradient, allowing protons to flow back without producing ATP (e.g., DNP).
Q: What happens to energy in the presence of an uncoupler? ANSWER It is
released as heat instead of being used to make ATP.
Q: What is the physiological uncoupling protein in brown adipose tissue?
ANSWER Thermogenin (UCP1).
Q: What are Reactive Oxygen Species (ROS)? ANSWER Highly reactive
molecules derived from incomplete reduction of oxygen (e.g., superoxide
anion).
Q: Which complexes primarily leak electrons to form ROS? ANSWER Complex I
and Complex III.
Q: What enzyme converts superoxide to hydrogen peroxide? ANSWER
Superoxide dismutase (SOD).
Q: How is hydrogen peroxide detoxified in the cell? ANSWER By catalase or
glutathione peroxidase.
Q: What is the P/O ratio? ANSWER The number of ATP molecules produced
per oxygen atom (1/2 O2) reduced.
Q: What inhibitor blocks electron flow at Complex I? ANSWER Rotenone.
Q: What inhibitor blocks electron flow at Complex III? ANSWER Antimycin A.
Q: What inhibitors block electron flow at Complex IV? ANSWER Cyanide,
carbon monoxide (CO), and azide.
Q: What inhibitor blocks ATP synthase directly? ANSWER Oligomycin.
Q: Why can't cytosolic NADH enter the mitochondria directly? ANSWER The
inner mitochondrial membrane is impermeable to NADH.
Q: What are the two main shuttles for cytosolic NADH? ANSWER The malate-
aspartate shuttle and the glycerol-3-phosphate shuttle.
, Q: Which shuttle yields more ATP and where is it found? ANSWER The malate-
aspartate shuttle (yields ~2.5 ATP), found in liver and kidney.
Q: What does the glycerol-3-phosphate shuttle yield and where is it found?
ANSWER Yields ~1.5 ATP (transfers electrons to FADH2), found in brain and
skeletal muscle.
Q: What is the total theoretical ATP yield from one molecule of glucose?
ANSWER Approximately 30-32 ATP.
Q: Where is ubiquinone located in the membrane? ANSWER It is deeply
embedded within the lipid bilayer of the inner mitochondrial membrane.
Q: Where is cytochrome c located? ANSWER Loosely attached to the outer
surface of the inner mitochondrial membrane.
Q: What metal ion is at the active center of cytochromes? ANSWER Iron (Fe).
Q: What metal ions are found in Complex IV? ANSWER Iron (heme) and copper
(Cu).
Section 2: Lipid Metabolism & Fatty Acid Oxidation (36-70)
Q: What are the three major types of dietary lipids? ANSWER Triglycerides,
phospholipids, and cholesterol.
Q: What enzyme digests dietary triglycerides in the small intestine? ANSWER
Pancreatic lipase.
Q: What is the role of bile salts in digestion? ANSWER They emulsify lipids,
increasing their surface area for lipase action.
Q: How are dietary fatty acids absorbed into intestinal cells? ANSWER As
mixed micelles.
Q: How are dietary lipids packaged for transport in the blood? ANSWER As
chylomicrons.
Q: Where does beta-oxidation of fatty acids occur? ANSWER In the
mitochondrial matrix.
Q: How are activated fatty acids transported into the mitochondria? ANSWER
Via the carnitine shuttle.
Q: What enzyme attaches carnitine to the fatty acid? ANSWER Carnitine
palmitoyltransferase I (CPT I).
