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Electron transport chain produces _____ _____ in the complex ______ _____
- metabolic water
- cytochrome c oxidase
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The goal of the electron transport chain is to get the protons to the ___________ region, not the ______ _____ region in order to make ATP. The protons will be used as _____ _____ and make ______/____ gradient
- inter-membranous region
- mitochondrial matrix region
- potential energy
- concentration gradient/ proton gradient
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Protein complex II is a/an ______ protein but not a/an ________. Meaning
- integral protein
- transmembrane protein
- It doesnt transport protons across the membrane
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Each subsequent protein complex is better at ______ electrons
accepting
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Electron transport cascade story pt 1: NADH
- Keep in mind we have a lot (10) of NADH from the citric acid cycle (6), glycolysis (2), pyruvate oxidation (2)
- NADH will bind to protein complex I (an enzyme) via redox reaction. NADH-Q reductase (protein complex I) gets the electrons
- As the electrons move to ubiquinone, they bring protons along with them (2 protons per 1 electron)
- NADH has 2 electrons so we get 4 protons
- Keep in mind the redox reaction turns NADH turned into NAD+ and a proton which is added to the mitochondrial matrix. We only got 3-1 protons to the inter-membranous region
- As we move our electrons from ubiquinone to protein complex III to cytochrome c, we get a total a total of 4 because we pumped two electrons. Total count is at 7 protons
- The electrons are transferred to water. As we move to get water we get two electrons, one proton per electron.
- We don’t get as many protons because it costs energy to create water. Its still a net of 4 protons if you remove the two protons already in the mitochondrial matrix
- So one NADH gave us a total of 11 protons and they can make *3.75 ATP
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Electrons transport cascade story pt 2 FADH
- 2 FADH2s (made in the citric acid cycle) cannot bind to complex I only complex II. So it does just that via redox reaction with the complex II.
- FADH2's oxidation leaves 2 protons in mitochondrial matrix.
- The electrons produced are transferred to ubiquinone (FADH2 produces 2 electrons)
- The electrons pump along 4 protons and the net differential will be 2 however, because for FADH2 leaves 2 protons in the matrix.
- By the end, we have a net total of 6 protons (The more valuable pump is NADH 11 vs 6 protons & 1 fewer proton in the matrix)
- The resulting proton gradient from NADH will exist on the inter-membranous side. Protons are then moved to ATP synthase to make ATP
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Electron transport cascade pt 3 ATP synthase
- Has 2 sub units F0 which is in the membrane and F1 (which is in the mitochondrial matrix and is the site of the reaction that makes ATP)
- Energy will be transferred via the potential energy from the concentration gradient of proton which is high inter-membranously and low in the matrix (proton motive force)
- When a proton comes in, F0 subunit (the drum) will move causing a proton to leave the drum and enter the matrix.
- The movement of the drum will transfer energy to gamma subunit causing it to torque or twist.
- That energy from the torque will be transferred to the F1 subunit and give it enough energy to take an inorganic phosphate and place it on and ADP
- 3 protons have to come across to make 1 ATP
- The concentration gradient is maintained so that we can continue to make ATP
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chemiosmosis
protons diffuse back (proton-motive force into the mitochondria through ATP synthase, a channel protein
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uncoupling
we can take away the movement of protons from making ATP and just let them and just let them go through to the matrix (via another H+ diffusion channel). The energy from that movement is lost as heat energy.
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______ is why smaller animals heat faster
Uncoupling
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________ is found in small animals and infant humans and helps them warm
thermogenin
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Thermogenin story
- causes uncoupling, the protons will go through it and into the matrix, instead of entering ATP synthase, so we get heat but no ATP
- We lose our proton gradient and in order to compensate, the body breaks down more glucose and other molecules. The metabolism will spike and there will be a hormonal release of T4 (thyroxine) as a result, to make a new proton concentration.
- Heat production will come from two sources breaking down of macromolecules and the thermogenin allowing protons into the matrix
- Not unsafe because the heating will be localized not uniform across the whole body
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DNP story
- DNPs are a proton ionophore (hole for ion, in this case protons).
- They will also allow protons to go from inter-membranous space to the matrix
- Yields heat energy but no ATP
- We lose our proton gradient and in order to compensate, the body breaks down more glucose and other molecules.
- DNP is actually taken systemically so unlike thermogenin, its effects are delocalized. It affects all cells in the body, and they will burn up all of their supply of resources to make a new proton gradient
- This will lead to hyperthermia as we burn to death
- *used to be a weight loss drug but was banned in a lot of places (the recommended dosage is very close to the lethal dosage)
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The purpose of lactic acid fermentation is to regenerate _____. This occurs in the _____ of _____ cells
- NAD+
- cytosol of muscle cells
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Fermentation story:
- 12 enzymatic reactions produce 2 NADHs that normally go to the mitochondria, but in fermentation there's no oxygen present
- For glycolsis to occur we need electron carriers (NAD+)
- We can't transport NADH to the mitochondria because if we do, NADH is oxidized and it'll undergo the regular cycle and make its way to the ATP synthase. If oxygen isn't available, none of this is possible.
- So instead, you have to move the electrons via electron carriers and eventually we will run out of them
- In order to free up the NAD+ to carry more electrons, there will be an enzymatic redox reaction where we transport electrons into the pyruvate lactate dehydrogenase
- Lactic acid has more electrons than pyruvate and lactic acid will help us store electrons
- The benefit will be that this will free up NAD+ so we can continue to perform glycolysis. The result is the production of some ATP which be good enough to postpone death
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Alcoholic fermentation story
*no enzyme name are need to know
- Every organism needs to do glycolysis
- Some organisms like yeast need to do alcoholic fermentation and will need to free up their electron carriers.
- Pyruvate dehydrogenase uses a decarboxylation reaction to remove CO2 from pyruvate (fizzy beer)
- Alcohol dehydrogenase then uses a redox reaction to remove electrons from acetylaldehyde
- This leaves us with ethanol
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In photosynthesis, plats will take in ____ in the atmosphere and lose some _____. This is necessary to get the O2 & CO2 in
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Plants stomata are little _____ that prevent water from ______ and mitigate movement of _____
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______ can be opened and closed for gas exchange but will cost a little _____ each time they open
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When CO2 lvls are high, plants have _____ stomata so they lose ____ water. When CO2 lvls are low, plants have _____ stomata so they lose _____ water
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The 2 pathways of photosynthesis involve reactions that use light _____ & _____ exclusively
directly & indirectly
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Light reactions use ______ energy and light independent reactions do not use ________ energy directly
- photonic energy
- photonic energy
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Light reactions convert light energy to chemical energy as ____ & _____ (plant's _____ _____)
ATP & NADPH (plant's electron carriers)
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Non cyclic pathway story:
- Light energy will hit chlorophyll molecules on the PS II
- The purpose is to get the reaction center enough energy to make it lose an electron
- The electron acceptor for P680 (now P680+) will be plastoquinone (an integral protein that uses the energy from electron movement to get protons to the next complex)
- P680 is now in need of electrons and will use its reaction center (on the thylakoid side) to make them by splitting water
- Water will be oxidized and electrons will go to P680+ returning it to the happy state of P680
- A byproduct will be O2 and 2 protons will be added to the thylakoid side
- The original electrons back in plastoquinone will go to the cytochrome complex (transmembrane) it will pump 2 protons per 1 electron
- This will give us our proton gradient
- Now we will go to plastocyanin(a peripheral protein) and then make our way to P700 aka PSI
- Presumably by this point, light has hit chlorophyll molecules in PSI and transferred energy around causing it to lose electrons to ferredoxin (PSI's electrons came from plastocyanin)
- Now we get P700+ and the electrons from ferredoxin will now move to ferredoxin-NADP reductase (FNR) which will use a redox reaction NADP (electron carrier) into NADPH
- Protons have been removed from the stroma side giving us our electron gradient to make ATP at ATP synthase
- Electrons in NADPH will also be used to make sugars later
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