EC 380 UPDATED EXAMS TEST PAPER QUESTIONS
AND ANSWERS SURE A+
✔✔Krebs cycle rate limiting enzyme - ✔✔isocitrate dehydrogenase
Increased activity
High [ADP] [AMP] [P] Ca 2+
Decreased activity
✔✔Oxidation of CHO: Electron Transport Chain (mitochondria) - ✔✔H+ and electrons
(e-) are produced from glycolysis conversion of pyruvate to Acetyl CoA and Krebs cycle
-Left along cell becomes too acidic
-H+, e- carried to electron transport chain via two coenzymes NAD+ and FAD+
Reduced from are NADH and FADH2
✔✔Oxidation of fat - ✔✔Triglycerides: major fat energy source
Broken down to 1 glycerol + 3 FFAs
Lipolysis, carried out by lipases
Rate of FFA entry into muscle depends on concentration gradient
Yields ~3 to 4 times more ATP than glucose
, Slower than glucose oxidation
✔✔oxidation of CHO energy yield - ✔✔1 glycogen= 33 ATP
✔✔B- oxidation of fat - ✔✔Process of converting FFAs to acetyl-CoA before entering
Krebs cycle
Requires up-front expenditure of 2 ATP
Number of steps depends on number of carbons on FFA
16-carbon FFA yields 8 acetyl-CoA
Compare: 1 glucose yields 2 acetyl-CoA
Fat oxidation requires more O2 now, yields far more ATP later
✔✔Oxidation of fat: Krebs cycle, electron transport chain - ✔✔Acetyl CoA enters Krebs
cycle
-Same path as glucose oxidation
-Different FFAs have different number of carbons
-> will yield different number of acetyl coA molecules
->ATP yield will be different for different FFAs
✔✔Oxidation of Protein (Amino Acids) - ✔✔Minimal use as a substrate (5-10% of total
EE)
Starvation, intense or prolonged exercise
Amino acids can be converted to
- glucose
-intermediates of oxidative metabolism
-Energy yield not easy to determine due to nitrogen
-Nitrogen excretion requires ATP expenditure
-Forms urea and excreted in urine
✔✔Control of oxidative phosphorylation: negative feedback - ✔✔Negative feedback
regulate Krebs cycle, regulates electron transport
-isocitrate dehydrogenase the rate limiting enzyme
-inhibited: increase high [ADP], [AMP], [P], Ca 2-
-Activated: increase high [ATP]
In turn regulates electron transport chain
Lactate is an important duel during exercise, typically formed in type 2 muscle cells
✔✔Muscles can utilize lactate in 3 ways: - ✔✔-Lactate produced in the cytoplasm can
be taken up by the mitochondria of the same muscle fiber and oxidized.
-Lactate can be transported via MCP transporters to another cell and oxidized there
(lactate shuttle).
-Lactate can recirculate back to the liver, reconverted to pyruvate and then to glucose
through gluconeogenesis.
AND ANSWERS SURE A+
✔✔Krebs cycle rate limiting enzyme - ✔✔isocitrate dehydrogenase
Increased activity
High [ADP] [AMP] [P] Ca 2+
Decreased activity
✔✔Oxidation of CHO: Electron Transport Chain (mitochondria) - ✔✔H+ and electrons
(e-) are produced from glycolysis conversion of pyruvate to Acetyl CoA and Krebs cycle
-Left along cell becomes too acidic
-H+, e- carried to electron transport chain via two coenzymes NAD+ and FAD+
Reduced from are NADH and FADH2
✔✔Oxidation of fat - ✔✔Triglycerides: major fat energy source
Broken down to 1 glycerol + 3 FFAs
Lipolysis, carried out by lipases
Rate of FFA entry into muscle depends on concentration gradient
Yields ~3 to 4 times more ATP than glucose
, Slower than glucose oxidation
✔✔oxidation of CHO energy yield - ✔✔1 glycogen= 33 ATP
✔✔B- oxidation of fat - ✔✔Process of converting FFAs to acetyl-CoA before entering
Krebs cycle
Requires up-front expenditure of 2 ATP
Number of steps depends on number of carbons on FFA
16-carbon FFA yields 8 acetyl-CoA
Compare: 1 glucose yields 2 acetyl-CoA
Fat oxidation requires more O2 now, yields far more ATP later
✔✔Oxidation of fat: Krebs cycle, electron transport chain - ✔✔Acetyl CoA enters Krebs
cycle
-Same path as glucose oxidation
-Different FFAs have different number of carbons
-> will yield different number of acetyl coA molecules
->ATP yield will be different for different FFAs
✔✔Oxidation of Protein (Amino Acids) - ✔✔Minimal use as a substrate (5-10% of total
EE)
Starvation, intense or prolonged exercise
Amino acids can be converted to
- glucose
-intermediates of oxidative metabolism
-Energy yield not easy to determine due to nitrogen
-Nitrogen excretion requires ATP expenditure
-Forms urea and excreted in urine
✔✔Control of oxidative phosphorylation: negative feedback - ✔✔Negative feedback
regulate Krebs cycle, regulates electron transport
-isocitrate dehydrogenase the rate limiting enzyme
-inhibited: increase high [ADP], [AMP], [P], Ca 2-
-Activated: increase high [ATP]
In turn regulates electron transport chain
Lactate is an important duel during exercise, typically formed in type 2 muscle cells
✔✔Muscles can utilize lactate in 3 ways: - ✔✔-Lactate produced in the cytoplasm can
be taken up by the mitochondria of the same muscle fiber and oxidized.
-Lactate can be transported via MCP transporters to another cell and oxidized there
(lactate shuttle).
-Lactate can recirculate back to the liver, reconverted to pyruvate and then to glucose
through gluconeogenesis.
