Chapter 10 Flashcards
Starting reactants and products of glycolysis, PDH reaction, Crebs cycle, and ETC.
The conversion of pyruvate ______ carbon molecule to acetyl-coA _____ carbon molecule is an (oxidation/reduction) reaction.
3 carbon, 2 carbon, oxidation
Steps of pyruvate dehydrogenase reaction:
1 glucose –> 2 pyruvates –> 2 Acetyl-coA, 2 NADH & 2 CO2
What is the main purpose of the citric acid cycle?
To oxidize carbons in intermediates to CO2 and generate high energy electron carriers (NADH & FADH2) and GTP.
What are some things that inhibit the PDH reaction?
Acetyl-CoA itself, NADH, ATP, pyruvate dehydrogenase kinase
The production of acetyl coA is regulated by two important enzymes to ensure the body doesn’t overproduce or underproduce it. What are they?
Pyruvate dehydrogenase kinase - this enzyme phosphorylates the other enzyme PDH to turn it off when acetyl-CoA levels are high
Pyruvate dehydrogenase phosphatase - this enzyme dephosphorylates PDH to turn it on, when acetyl-CoA levels are low, and ADP levels are high
What is the role of pyruvate dehydrogenase? What are characteristics of it?
It is a 3 enzyme complex with multiple subunits, in charge of the oxidation & decarboxylation of pyruvate to create acetyl-coA.
What are other ways that Acetyl-CoA can be formed?
It can be formed from ketogenic amino acids, ketone bodies, alcohol, and fatty acids
Describe the process of how acetyl-coA is created from fatty acids.
- In the cytosol of the cell, a fatty acid couples with CoA forming fatty acyl CoA
- This complex travels to the intermembrane space of the mitochondria where the acyl group is transferred to a molecule called carnitine
- Acyl-Carntitine can cross the inner membrane, UNLIKE the CoA
- Acyl group is transferred to a mitochondrial coA enzyme once again forming Acyl-coA
5.Acyl-CoA undergoes beta-oxidation to form acetyl-CoA
Where does the citric acid cycle occur?
Mitochondrial matrix; innermost compartment
Citric Acid Cycle reactants and products
What is the rate-limiting step of the TCA cycle?
The rate-limiting enzyme is isocitrate dehydrogenase which converts isocitrate to alpha-ketoglutarate. It is rate-limiting because this step is inhibited by elevated ATP & NADH.
what is the net ATP yield from 1 glucose?
30-32 ATPs
2 ATP from glycolysis + 2 ATP from TCA cycle + 28 ATP from ETC chain = 32 max ATP
1 NADH produces _____ ATP.
1 FADH2 produces _____ ATP.
NADH = 2.5
FADH2 = 1.5
The electron transport chain generates a high concentration of protons in the (intermembrane space/mitochondrial matrix). The ETC is located in the (intermembrane space/inner membrane/matrix).
Intermembrane space; inner membrane
What is oxidative phosphorylation, and where does it occur?
The process where energy is harnessed through a series of protein complexes embedded in the inner-membrane of mitochondria (called ETC and ATP synthase) to create ATP.
Occurs in the inner membrane of the mitochondria.
Describe ATP synthase
Enzyme complex in the ETC chain made of two portions:
F0 - the non polar ion channel spanning the membrane, which allows protons to flow down their gradient
F1 - uses the energy released by the electrochemical gradient to phosphorylate ADP –> ATP
What does the proton gradient do in the ETC? What is the significance of ADP for the enzyme ATP synthase?
The proton gradient provides energy for ATP synthase to rotate. to release an ATP molecule.
ADP is necessary because it is the substrate which allows it to be converted into ATP once bound to the enzyme.
As the ETC chain progresses, the reduction potentials of each complex (increase/decrease).
Increase because the final electron acceptor O2 has the highest reduction potential
Chemiosmotic coupling
Direct relationship which pairs the exergonic process of H+ traveling through the ATP synthase to the endergonic process of phosphorylating ADP.
Coupling refers to the energy released from one reaction driving the second reaction.
How does the concentration of O2 affect the rate oxidative phosphorylation and NADH/FADH2.
Decreased O2 causes decreased oxidative phosphorylation and increased NADH/FADH2
Complex I of ETC (NADH-CoQ oxoreductase)
Electrons passed from NADH –> FMN –> Fe-S subunit –> Coenzyme Q (ubiquinone) –> becomes CoQH2 (ubiquinol)
-4 protons pumped into intermembrane space
Complex II of ETC (Succinate-CoQ oxidoreductase)
Electrons passed from succinate –> FAD which becomes FADH2 –> Fe-S subunit –> Coenzyme Q (ubiquinone) –> becomes CoQH2 (ubiquinol)
-No proton pumping occurs at this complex
Complex III of ETC
Coenzyme Q from both Complex I and Complex II travels to Complex III to transfer its electrons to cytochrome C
Coenzyme Q also donates 2 protons to Complex III to be pumped into intermembrane space
-4 protons pumped into intermembrane space:
2 from Coenzyme Q and two from the reaction of transferring e- from coenzyme Q to cytochrome C
