Klappaβ-Oxidation of Fatty Acids
Tier 2 · #15 of 33 · high yield · topic 3.11 — every high-yield fact from the book chapter, exam-ready.
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- FrontIn which subcellular compartment does β-oxidation of fatty acids occur?BackThe mitochondrial matrix
- FrontWhat is the direct substrate that enters β-oxidation (not the free fatty acid)?BackAcyl-CoA
- FrontWhich four tissues are the main sites of fatty-acid β-oxidation ?BackHeart , skeletal muscle , kidney , and liver
- FrontIn which metabolic states are fatty acids the crucial energy source?BackThe postabsorptive and fasted states
- FrontWhich tissue oxidizes fatty acids as a preferred fuel even when glucose is plentiful?BackThe heart (also skeletal muscle and kidney )
- FrontWhy can red blood cells not oxidize fatty acids?BackThey have no mitochondria
- FrontWhy does the brain not use fatty acids directly as fuel?BackFatty acids don't cross the blood–brain barrier well
- FrontDuring prolonged fasting, what fuel (besides glucose) does the brain rely on?BackKetone bodies
- FrontWhich enzyme activates a free fatty acid by attaching Coenzyme A ?BackAcyl-CoA synthetase ( thiokinase )
- FrontOn which membrane does activation of long-chain fatty acids by acyl-CoA synthetase occur?BackThe outer mitochondrial membrane
- FrontIn fatty-acid activation, ATP is split not to ADP + Pᵢ but all the way to ______.BackAMP + PPᵢ ( pyrophosphate )
- FrontWhy is fatty-acid activation counted as a cost of 2 ATP rather than 1?BackGoing from ATP to AMP breaks two high-energy phosphate bonds (PPᵢ is then hydrolyzed to 2 Pᵢ)
- FrontIn the palmitate ATP balance, how many ATP are subtracted for activation, and how many times is it paid?BackSubtract 2 , paid once for the whole molecule ( not per cycle )
- FrontWhere are very-long-chain fatty acids ( VLCFA ) activated?BackIn peroxisomes
- FrontWhy must the carnitine shuttle exist — what can long-chain acyl-CoA not do?BackThe inner mitochondrial membrane is impermeable to acyl-CoA , so it cannot cross into the matrix
- FrontWhich enzyme of the carnitine shuttle swaps CoA for carnitine on the outer membrane?BackCPT-I ( carnitine palmitoyltransferase I )
- FrontWhat molecule is produced when CPT-I swaps CoA for carnitine ?BackAcylcarnitine
- FrontWhich protein carries acylcarnitine across the inner mitochondrial membrane?BackThe translocase ( carnitine–acylcarnitine transporter )
- FrontWhat does CPT-II do once acylcarnitine is inside the matrix?BackRemoves carnitine and re-attaches CoA , regenerating acyl-CoA in the matrix
- FrontWhat is the rate-limiting, committed step of fatty-acid oxidation?BackCPT-I
- FrontWhat is the single exam-critical inhibitor of CPT-I ?BackMalonyl-CoA
- FrontStep 1 of the β-oxidation spiral: which enzyme creates a trans double bond and which cofactor is reduced?BackAcyl-CoA dehydrogenase ; FAD → FADH₂
- FrontStep 2 of the β-oxidation spiral: which enzyme adds water across the double bond?BackEnoyl-CoA hydratase
- FrontStep 3 of the β-oxidation spiral: which enzyme oxidizes the hydroxyl to a keto group and which cofactor is reduced?Backβ-hydroxyacyl-CoA dehydrogenase ; NAD⁺ → NADH
- FrontStep 4 of the β-oxidation spiral: which enzyme cleaves off acetyl-CoA using CoA-SH?BackThiolase
- FrontIn the two oxidation steps of β-oxidation , which cofactor is used FIRST and which SECOND?BackFirst FAD , then NAD⁺
- FrontWhat are the four steps of the β-oxidation spiral in order (one-word chemistry)?BackOxidize → hydrate → oxidize → cleave
- FrontOne full turn of the β-oxidation spiral produces how many carbons removed and which products?Back−2 carbons ; +1 acetyl-CoA , +1 FADH₂ , +1 NADH
- FrontHow many β-oxidation cycles does palmitate (C16) require?Back7 cycles (not 8)
- FrontWhy does C16 palmitate take 7 cycles rather than 8?BackThe final cycle splits a 4-carbon unit into two acetyl-CoA at once
- FrontComplete β-oxidation of palmitate (C16) yields how many acetyl-CoA, FADH₂, and NADH?Back8 acetyl-CoA, 7 FADH₂, 7 NADH
- FrontFor an even-chain fatty acid of n carbons, how many cycles and how many acetyl-CoA result?Back(n/2 − 1) cycles and (n/2) acetyl-CoA
- FrontWhat is the net ATP yield from complete oxidation of palmitate (using FADH₂≈1.5, NADH≈2.5, acetyl-CoA≈10)?Back≈106 ATP net (108 gross − 2 activation)
- FrontWhat 3-carbon residue is left when an odd-chain fatty acid spirals down?BackPropionyl-CoA
- FrontWhat is the salvage pathway for propionyl-CoA (the 3-intermediate sequence)?BackPropionyl-CoA → methylmalonyl-CoA → succinyl-CoA
- FrontWhich vitamin does propionyl-CoA carboxylase require?BackBiotin
- FrontWhich vitamin does methylmalonyl-CoA mutase require?BackVitamin B12 ( cobalamin )
- FrontWhy are odd-chain fatty acids mildly glucogenic ?BackTheir final product is succinyl-CoA , a TCA-cycle intermediate that can feed glucose synthesis
- FrontWhat metabolite accumulates in vitamin B12 deficiency , serving as a clinical clue?BackMethylmalonic acid
- FrontWhy must a cell never run fatty-acid synthesis and β-oxidation at the same time?BackIt would be a futile cycle , burning ATP for nothing
- FrontWhich enzyme makes malonyl-CoA , and it is the committed step of which pathway?BackAcetyl-CoA carboxylase (ACC) ; committed step of fatty-acid synthesis
- FrontIn the FED state: insulin status, malonyl-CoA level, CPT-I , and β-oxidation ?BackInsulin high → ACC on → malonyl-CoA high → CPT-I blocked → β-oxidation OFF
- FrontIn the FASTING state: glucagon status, malonyl-CoA level, CPT-I , and β-oxidation ?BackGlucagon high → ACC off → malonyl-CoA low → CPT-I open → β-oxidation ON
- FrontWhich ACC isoenzyme makes malonyl-CoA used as the building block for fatty-acid synthesis ?BackACC1 ( cytosolic; liver and lipogenic tissues )
- FrontWhich ACC isoenzyme makes malonyl-CoA whose main job is to inhibit CPT-I ?BackACC2 ( mitochondrial; heart and muscle )
- FrontWhich enzyme lowers malonyl-CoA , releasing the brake on CPT-I ?BackMalonyl-CoA decarboxylase (MCoADC)
- FrontUsing the OLDER P/O convention (FADH₂ = 2, NADH = 3), what is the gross and net ATP yield from complete oxidation of palmitate (C16)?Back129 gross, 127 net (after −2 for activation)
- FrontWhy can the same palmitate give either ≈106 net or 127 net ATP — what differs?BackThe P/O convention used : FADH₂≈1.5/NADH≈2.5 gives ≈106 net; the older FADH₂=2/NADH=3 gives 127 net
- FrontWhere are medium-chain fatty acids (MCFA) activated?BackInside the mitochondrial matrix
- FrontMatch the chain length to its site of activation: LCFA , VLCFA , MCFA .BackLCFA = outer mitochondrial membrane; VLCFA = peroxisome; MCFA = mitochondrial matrix
- FrontUsing the P/O values this course uses, how many ATP does one FADH₂ from β-oxidation yield?Back≈1.5 ATP
- FrontUsing the P/O values this course uses, how many ATP does one NADH from β-oxidation yield?Back≈2.5 ATP
- FrontHow many ATP does one acetyl-CoA yield through the TCA cycle plus the electron transport chain?Back≈10 ATP
- FrontWhich kinase, together with glucagon , phosphorylates and inactivates ACC during fasting?BackAMPK
- FrontWhy is the pathway called β-oxidation — at which carbon is the bond cut?BackThe cut is made at the β-carbon (the second carbon down from the carboxyl end)
- FrontMalonyl-CoA plays a dual role linking fat synthesis and breakdown — what are its two roles?BackIt is the committed-step product (signal) of fatty-acid SYNTHESIS , and the inhibitor of CPT-I that shuts off fatty-acid BREAKDOWN
- FrontPropionyl-CoA carboxylase needs biotin — what is the general rule this illustrates about carboxylase enzymes?BackAll carboxylases require biotin as a cofactor
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