ETC & Oxidative Phosphorylation Flashcards
What inactivates ETC Complex I?
Retonone & Riboflavin deficiency (Vitamin B1)
How is ATP moved from the matrix, where it is produced, to the intermembrane space?
Via the adenosine nucleotide translocase. This is an antiporter that moves ATP from the matrix to the intermembrane space and ADP from the intermembrane space to the matrix
What is the mechanism of the ATP synthase?
The ATP synthase utilizes the chemical potential of H+ produced by the ETC to synthesize ATP from ADP and Pi. In the process, H+ is pumped down its concentration gradient from the intermembrane space into the matrix.
Where is ATP produced?
Mitochondrial matrix
What ETC complex is inhibited by CO?
Complex IV
Explain the function and mechanism of the Malate-Aspartate shuttle.
NADH produced from glycolysis is unable to cross the inner-membrane to the matrix.
In the intermembrane space, NADH transfers an electron to oxaloacetate to form malate via the malate dehydrogenase. Malate then enters the matrix via the malate-alpha ketoglutarate transporter. Within the matrix, the malate dehydrogenase reforms NADH and oxaloacetate from malate. NADH can then enter the ETC.
Oxaloacetate is then converted to glutarate via the aspartate aminotransferase. The glutarate is moved from the matrix to the intermembrane space via the glutamate-aspartate transporter. Alpha ketolutarate can then be reformed from aspartate.
In what tissues is the Glycerol-3-Phosphate shuttle found?
Brain & muscle
In what tissues is the malate-aspartate shuttle system found?
Kidney, liver, and heart
What is the function of Thermogenin?
Thermogenin is an uncoupling protein located in the mitochondrial inner membrane. It oxidizes NADH and FADH2 to form an H+ gradient. The gradient is then used to generate heat without ATP production.
What inactivates ETC Complex IV?
CO, cyanide, Fe deficiency, Cu deficiency
What inactivates ETC Complex II (CoQ)?
Malonate
What is the difference between electro potential and chemical potential?
Electro potential is the result of differences in charges. Chemical potential is the result of differences in molecule concentrations.
What molecule inhibits the ATP synthase? How?
Oligomycin - binds to Fo of the ATP synthase and blocks the H+ channel
What transporters exist in the inner membrane of mitochondria?
Adenosine nucleotide translocase - antiporter
ATP synthase - uniporter
Phosphate translocase - symporter
Describe the structure and function of the ETC.
The ETC is composed of 4 complexes - I, II, III, & IV.
By oxidizing NADH to NAD+, Complex I pumps four H+ from the matrix to the intermembrane space. Electrons are picked up by Complex II (CoQ/Cytochrome C) and carried to Complex III. Electrons are then carried from Complex II to Complex IV via CoQ, with the pumping of 2 H+. Complex IV moves electrons to O2 as the final electron acceptor.
Describe the structure of mitochondria.
Mitochondria contain a double membrane. The outer-membrane is permeable, with the exception of large proteins. Within the outer membrane is the intermembrane space, which includes the cytoplasm. The inner-membrane is non-permeable and includes the matrix within. This is the site of TCA and oxidative phosphorylation.
Explain the difference in H+ pumping for NADH & FADH2.
Electrons from NADH are delivered to Complex I, resulting in 10 H+ pumped.
Electrons from FADH2 are delivered directly to Complex II, skipping Complex I, and thus resulting in only 6 H+ pumped.
NADH is unable to pass from the intermembrane space into the matrix. How then is NADH able to enter the ETC?
Electrons from NADH are transferred from the intermembrane space to the matrix where NADH is reformed. This is done with assistance from malate, aspartate, and alpha ketoglutarate.
