Biochemistry Chapter 8: Aerobic Carbohydrate Metabolism Flashcards
What do diabetic patients rely on for metabolism if in a state of extended hyperglycemia?
Fat metabolism. Therefore, ketones will be found in the urine
Dysglycemia
refers to abnormal blood glucose levels, encompassing both hyperglycemia (high blood sugar) and hypoglycemia (low blood sugar), often associated with conditions like diabetes or metabolic syndrome.
True or false: GLUT2 transport protein is expressed primarily in the liver and pancreas. Therefore, GLUT2 deficiency would result in stunted growth.
TRUE. The signaling required for glucose metabolism would be unable to effectively provide glucose to growing tissues, and glycogen stored in the liver could not be effectively released to tissues, so avoiding significant complications for a growing child would require the strictest possible dietary monitoring
Cyanide poisoning is the result of an impaired
ETC function
Substrate level phosphorylation
Add phosphate group to derivative of glucose and then add ADP
Oxidative Phosphorlaytion
NADH FADH2 etc are oxidized to create a proton gradient and then pumped back through ATP synthase to catalyze phosphorlyation of ADP into ATP
ETC requires oxygen _______ whereas krebs cycle require oxygen _________
Directly, indirectly
Goal of the Krebs Cycle
is to generate high-energy electron carriers (NADH and FADH₂) and intermediates for ATP production, which fuel the process of oxidative phosphorylation in cellular respiration
Location of Krebs Cycle
In eukaryotes, mitochondrial matrix
Pyruvate dehydrogenase complex (PDC)
converts pyruvate to acetyl-CoA before entering citric acid cycle → 1 NADH generated.
Net products of Critic Acid Cycle per turn
1 GTP, 3 NADH, 1 FADH₂, 2 CO₂.
Stoichiometry: each glucose molecule = how many turns of the TCA?
2 turns of citric acid cycle.
Citric Acid cycle is a metabolic crossroads in the body because
Byproducts of other molecules (lipids, proteins) can enter into citric acid cycle, and intermediates of citric acid cycle are precursors for other metabolic processes
Start of citric acid cycle
acetyl-CoA (2C) + oxaloacetate (4C) → citrate (6C)
Step 3 citric acid cycle
isocitrate (6C) → α-ketoglutarate (5C)
Step 4 citric acid cycle
α-ketoglutarate (5C) → succinyl-CoA (4C)
Principle of ETC
electrons transferred along series of carriers, moving from carriers with lower reduction potentials to those with higher reduction potentials
ETC is like what kind of electrochemical cell
similarly to a galvanic cell
Energy from ETC
pumps protons into intermembrane space, creating proton gradient
Electron transfer in the ETC involves what structures?
Complexes I, II, III, IV are embedded in inner mitochondrial membrane, and together with electron carriers Q and cytochrome c are used in electron transfer
Final electron acceptor in ETC
Oxygen is the final electron acceptor in the ETC and is reduced to H₂O.
Electrochemical energy of proton gradient is used to power
is used to power ATP synthase, which attaches a phosphate group to ADP to form ATP.
↑ATP, ↑products of citric acid cycle =
↓citric acid cycle
↑ADP (showing that cell needs energy)
↑citric acid cycle
↑ADP = ____ oxidative phosphorylation
↑ETC/oxidative phosphorylation.
electron transport chain (ETC) takes place
across the inner mitochondrial membrane, specifically between the mitochondrial matrix and the intermembrane space
goal of the electron transport chain
To generate a proton gradient (H⁺ gradient) across the inner mitochondrial membrane, which drives the synthesis of ATP
Input and Output of Krebs Cycle (per 1 turn)
Input:
1) Acetyl-CoA (2-carbon molecule): Derived from pyruvate via the pyruvate dehydrogenase complex.
2) Oxaloacetate (4-carbon molecule): Combines with acetyl-CoA to form citrate.
3) 3 NAD⁺: Electron carrier that gets reduced to NADH.
4) 1 FAD: Electron carrier that gets reduced to FADH₂.
5) 1 GDP (or ADP): Used to form GTP (or ATP) via substrate-level phosphorylation.
6) 2 H₂O: Water molecules used in enzymatic reactions during the cycle.
Output:
1) 2 CO₂: Released as byproducts of acetyl-CoA oxidation.
2) 3 NADH: High-energy electron carrier for the electron transport chain.
3) 1 FADH₂: High-energy electron carrier for the electron transport chain.
4) 1 GTP (or ATP): Usable energy via substrate-level phosphorylation.
5) Oxaloacetate: Regenerated to combine with another acetyl-CoA for the next cycle.
Net Inputs and Outputs for 1 Glucose
Since 1 glucose molecule produces 2 acetyl-CoA molecules, the Krebs cycle runs twice per glucose
Inputs (2 Turns of Krebs Cycle for 1 Glucose):
2 Acetyl-CoA
6 NAD⁺
2 FAD
2 GDP (or ADP)
4 H₂O
Outputs (2 Turns of Krebs Cycle for 1 Glucose):
4 CO₂
6 NADH
2 FADH₂
2 GTP (or ATP)
2 Oxaloacetate (regenerated)
ATP per NADH
2.5 molecules
ATP per FADH2
1.5
Grand Total ATP Yield per Glucose
pyruvate decarboxylation produces
acetyl CoA for the Citric Acid Cycle
The electron carriers in the ETC can transport a maximum of ____ electrons
1 - 2
UTP tags glucose for what
Glycogen synthesis
ATP consists of three phosphate groups:
ATP consists of three phosphate groups:
α-phosphate (alpha) – directly attached to the ribose sugar.
β-phosphate (beta) – middle phosphate.
γ-phosphate (gamma) – outermost phosphate.
Can Glutamate be used in the krebs cycle?
Yes, Glutamate is converted into α-ketoglutarate, which enters the Krebs cycle (TCA cycle) to generate ATP.
Complex I ETC name
NADH: ubiquinone oxidoreductase
Complex 2 ETC name
succinate dehydrogenase
Complex III ETC name
Ubiquinol–cytochrome c oxidoreductase
Complex IV ETC name
cytochrome c oxidase
How is ATP electrophilic even though it has a negative charge?
Despite being negatively charged, the phosphorus atom in ATP’s phosphate groups is still electron-deficient due to electronegative oxygen atoms pulling electron density away.
Electrostatic strain from negative charges makes ATP’s γ-phosphate highly reactive.
Magnesium ions (Mg²⁺) help stabilize negative charge, further increasing ATP’s electrophilicity.
Resonance stabilization in phosphate groups makes ATP hydrolysis favorable, encouraging nucleophilic attack.
End result of the Conversion of 1 pyruvate to Acetyl-CoA
1 NADH is produced
1 CO₂ is released
1 Acetyl-CoA is formed
