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49 Cards in this Set

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  • Back
What are the two pathways that bring NADH into the mitochondria?
Malate shuttle and the glycerol-Phosphate shuttle
How does NADH get into the mitochondriavia the malate shuttle?........ glycerol-phosphate shuttle?
To get in through the malate shuttle the NADH gives it H with electrons to oxaloacetate, which converts it to malate, which can easily cross the mitochondrial membrane through it’s shuttle, and then converts back to NADH………….. The glycerol phosphate shuttle converts the NADH to FADH2, which can go into the electron transport chain
What part of the electron transport chain does NADH give it’s electrons to?
Complex I, aka NADH dehydrogenase
Where do the electrons go from NADH dehydrogenase?
Coenzyme Q, aka obiquinone
Where do the electrons go from coenzyme Q?
Complex III, aka cytochrome B and C1
Where do the electrons go from complex III, aka cytochrome B / C1?
Cytochrome C
Where do the electrons go from cytochrome C?
Complex IV, aka cytochrome A/A3, aka cytochrome oxidase
What is special about cytochrome oxidase?
It’s heme groups contain copper instead of iron.
Where do the electrons go after cytochrome oxidase?
They are picked up by oxygen to produce H2O.
What are the complexes responsible for transferring FADH2 electrons into the electron transport chain?
Glycerol-Phosphate Shuttle (from cytoplasm)………..Succinate dehydrogenase, aka complex II………. Fatty Acyl CoA dehydrogenase
Where do the electrons coming in from FADH2 go to?
Directly to Coenzyme Q, aka ubiquinone, bypassing complex I
What are the three “plugs” or proton pumps in the mitochondrial membrane?
Complex I, III, and IV
What do the proton pumps do?
They pum H+ outside the mitochondria in order to duild up a concentration gradient of Hydrogen outside the mitochondria.
Hoe does Hydrogen get back into the mitochondria?
It goes through the F0 subunit of the ATP synthase enzyme.
What are the subunits of ATP synthase and what do they do?
F0 and F1. F0 is a channel for protons to reenter the mitochondria. F1 has ATP synthase activity and phosphorylase ADP to ATP. It gets it’s energy from the protons flowing down their gradient through the F0 subunit.
On what side of the mitochondrial membrane is the ATP produced?
It is produced on the mitochondrial side of the mitochondrial membrane
How does the atp get out of the mitochondria after it is produced?
It is exchanged for ADP through ATP/ADP translocase
What happens in hypoxia?
The electrons do not have a reciever, thus the electrons stop flowing and NADH accumulates, which shuts down the Krebs cycle. Therefore the proton gradient dissipates and there is no more ATP made.
Which drugs inhibit Complex I, aka NADH dehydrogenase, of the ETC?
Barbituates and Rotenone
Which drugs inhibit Complex iV, aka cytochrome A/A3, aka cytochrome oxidase?
Cyanide, Carbon Monoxide, and Azide
What often causes cyanide toxicity?
Nitroprusside administration and as a result of fires
What often causes carbon monoxide poisoning?
Use of space heaters in the winter.
Which drug inhibits ATP synthase?
What is the mechanism of oligomycin inhibition of ATP synthase?
It blocks the flow of protons through the F0 subunit. Thus the concentration of protons in the cytoplasm increases. Once it increases to a certain level, the electron transport chain senses this and shuts down. Thus the electron chain is shut down and even though there is still a strong gradient there will be be ATP produced because the F0 subunit of the ATP synthase is blocked
Which drugs are known as uncouplers?
2,4 DNP and thermogenin (brown adipose) and high doses of salicylates
How do uncouplers work?
They are molecules that can combine with protons and are able to cross the mitochondrial membrane into the mitochondria, thus bringing the proton into the mitochondria and reducing the proton gradient
What are the two effects of uncouplers?
1. reduce ATP synthesis due to lack of proton gradient ………….2. increase the electron transport chain due to the lack of proton gradient
How many ATP are produced by one NADH molecule? ... FADH2 molecule?
NADH = 3 .... FADH2 = 2
What is the difference between glycogen use in tliver and muscle?
In the liver, the glycogen stored in not for the use of the liver. In the liver the glycogen stored is for the use of the red blood cells and the brain cells. In the muscles, all of the glycogen stored is for the use of the muscles only.
What triggers glycogen gynthesis?
As ATP build up and the ETC, Krebs cycle, and glycolysis slow down, GLUCOSE-6P builds up and this is what triggers glycogen synthesis
What is the form of glucose used to package glucose as glycogen?
What is the rate limiting step of glycogen synthesis?
The activation of glycogen synthase by glucose, locally, and insulin, globally
What are the two enzymes involved in glycogen synthesis?
Glycogen synthase and branching enzyme
What are the steps in the synthesis of glycogen?
Glucose to glucose 6-P to glucose 1-P to UDP-glucose via UTP. UDP glucose is then chained together by glycogen synthase and branching enzyme
What are the two enzymes involved in the breakdown of glycogen?
Glycogen phosphorylase and debranching enzyme
What triggers the breakdown of glycogen?
Glucogon triggers the breakdown in the liver……………epinephrine controls the breakdown in liver and muscle………….and AMP controls the breakdown in muscle
After glycogen is broken down in the muscle what happens to it?
It is converted to Glucose-1P by glycogen phosphorylase and debranchig enzyme, then it is converted by glucose -6P and then proceed to go through glycolysis
Which enzyme in the liver convets glucose 6P to glucose?
Glucose 6P phosphatase
What happens to glycogen when it is broken down in the liver cell?
It is converted to Glucose-1P, which is then converted by Glucose 6P, which is then converted back to glucose via Glucose 6 phosphatase
What is the only clel that has glucose 6P phasphatase
Liver cell
What is G6PD
It is Glucose 6 phosphatase deficiency
What type of bonds does glycogen synthase make?
Alpha 1,4 bonds
What does the branching enxyme of glycogen synthesis do? .... How many glucose molecules from the end does branching enzyme break the bond?
It breaks alpha 1,4 bonds about 6-8 glucose molecules from the end……….. after breaking off the end of the chain it goes back about 4 glucose molecules on the original chain and then makes an alpha 1,6 bond to create a branch.
In summary what are the effects of branching enzyme
It breaks an alpha 1,4 bonds, goes back a few glucoses and then makes an alpha 1,6 bond
What happens after branching enzyme makes it’s branches?
Glycogen synthase extends both branches
What will glycogen phosphorylasae do?
It will break alpha 1,4 bonds to release glucose 1-P until it encounter the first branch point
What does debranching enzyme do?
Debranching enzyme breaks the alpha 1,4 bond nearest the branch point and transfers the oligoglucoes unit to the end of another chain and then goes back and hydrolyses the alpha 1,6 bond releaseing a single slucose from the former branch
What are the inhibitors of glycogen synthase in liver and muscle?
Liver = glucagons and epinephrine …………..Muscle = epinephrine