L11- Electron Transport Chain Flashcards
What are the four stages of Aerobic Respiration?
step 1- pyruvate decarboxylation - matrix
step 2- krebs/citric acid cycle - matrix
step 3- electron transport chain - cristae
step 4- ADP to ATP - cristae
What does the term OXIDATIVE PHOSPHORYLATION refer to?
the combined processes of the ELECTRON TRANSPORT CHAIN and ATP SYNTHASE PHOSPHORYLATION
Saying Proton or Hydrogen Ion is the same thing, what is the shorthand for this?
H+
this is just a hydrogen atom striped of its electron so it has a positive charge
What is the shorthand for Electron?
e-
What is the shorthand for Oxygen?
O2
What do we get from PYRUVATE DEHYDROGENASE/DECARBOXYLATION?
1 NADH
1 CO2
1 acetyl group which enters the krebs via ACA
What is released during KREBS CYCLE?
3 NADH 1 FADH2 2 CO2 succinic acid (all released into the matrix)
What is the result of the ELECTRON TRANSPORT CHAIN?
transferring electrons through the ETC creates a buildup of H+ ions
What is produced from ATP SYNTHASESPHORYLATION?
ATP is produced from matrix supply of ADP by harnessing the H+ gradient
Concentrated H+ in the inter membrane space is allowed to leak back into the mitochondrial matrix by ATP SYNTHASE. What occurs via this desire of H+ to equilibrate?
ATP Synthase phosphorylates ADP TO ATP
The ETC is a series of how many enzyme complexes?
4 enzymes complexes: I II III IV
the primary pathways is I-III-IV (electrons transported through UBIQUINONE, then complexes III and IV)
the second pathway II-III-IV (succinic acid passes electrons on to complexes III and IV)
very basic summary
The ETC is a series of how many enzyme complexes?
4 enzymes complexes: I II III IV
the primary pathways is I-III-IV (electrons transported through UBIQUINONE, then complexes III and IV)
the second pathway II-III-IV (succinic acid passes electrons on to complexes III and IV)
very basic summary
What cofactors are used during NADH dehydrogenase in Complex I?
flavin mononucleotide (FMN) Fe-S clusters
How many H+ are pumped from the matrix into the intermembrane space in Complex I?
4 H+ are pumpbed from the matrix into the intermebrane space
What happens to the Ubiquinone when it gets the electron from complex I?
It is hydrolyzed into ubiquinol (QH2)
What is Ubiquinone?
a non polar vitamin like coenzyme and antioxidant.
CoQ10
since it is non polar it diffuses laterally through the non polar layer (in the phospholipid bilayer) of the cristae membrane to transport its electrons to complex III
What accepts the electrons from the Ubiquinol and passes them on to complex III?
Iron Sulfate Clusters
Fe-S
An electron is highly polarized. How does it get into the non polar environment of the cristae?
using Fe-S (iron sulfur) clusters transports the electron.
When the Fe-S gets an e- it transports it into the innermembrane to the ubiquinone, where the electron makes QH2 (ubiquinol) which helps to move the electron laterally through the non polar membrane.
After the ubiquinol brings the electron to complex III, what happens? - in a very simplified way
Cytochrome C takes the electron from the Ubiquinol and leaps out of complex III to complex IV via it’s heme ring center. The Ubiquinol is further broken down.
What happens in complex IV? - in a highly simplified way
Complex IV is - Cytochrome C Oxidase, a multi subunit quaternary enzyme complex.
Last complex of the Electron Transport Chain.
accepts electrons from cytochrome c which reduces oxygen.
It then makes water from O2 and H+ in a complex process.
What cofactors does complex IV need?
copper, zinc and magnesium
In Complex II, What are the dual uses of Succinate Dehydogenase? Where is it made and where is it found?
Made in the Krebs Cycle.
Found embedded in the cristae (only enzyme from krebs to do this).
1) passes Hydrogen from succinate in the krebs directly into the ETC.
2)the succinate donates Hydrogen to FAD to become FADH2 which then carries the Hydrogens into the ubiquinone which makes it ubiquinol and enters the ETC in complex III.
Why is complex II special?
it is the only complex that does not pump H+ into the intermembrane space. It also doubles the efficiency of the Electron Transport Chain.
What is the enzymatic process happening in Complex I of the Electron Transport Chain?
NADH Dehydrogenase
What is the enzymatic process happening in Complex II of the Electron Transport Chain?
succinate dehydrogenase
What is the enzymatic process happening in Complex III of the Electron Transport Chain?
Cytocrome C Oxidoreductase
What is the enzymatic process happening in Complex IV of the Electron Transport Chain?
Cytochrome C Oxidase
How many subunits does Complex I - NADH Dehydorgenase have? Where is it found? Simply, what happens here?
46-subunit enzyme found in the cristae.
It oxidizes NADH and passes the electrons from the hydrogen through the flavin mononucleotide (FMN) and the Fe-S clusters into Ubiquinone creating Ubiquinol while H+ is being pumped into the intermembrane space
When Ubiquinol is stripped of its electrons onto Cytochrome C in complex III - cytochrome C Oxidoreductase, what happens to the ubiquinone?
it is recycled and picks up more hydrogen/electrons from complex I and complex II.
What is Complex I in the ETC?
NADH dehydrogenase
What is ATP synthase and where is it located?
a giant quarternary (4°) enyme embedded in the cristae membrane.
What is the function of ATP synthase?
It channels H+ through the complex. The complex rotates in response to the low pH of the intermembrane space. This rotation catalyses the synthesis of ATP from ADP which is released into the matrix and transported out of the mitochondrion into the cytoplasm of the cell making it available for cellular function.
How many ATP are released per glucose molecule in Glycolysis (anaerobic respiration)?
2 ATP
How many ATP are released in aerobic respiration when it is operating efficiently per glucose molecule?
38 ATP
True or false: aerobic respiration is very efficient
false: there are inefficiencies in aerobic respiration
Where is the superoxide molecule formed?
In complex I, it needs superoxide dismutase to reduce it. this is an example of an inefficiency.
Much ATP is needed to shunt the substrates of aerobic respiration into the mitochondrion via transport proteins. Name some of these substrates.
pyruvate ACA vitamins ADP mineral ions etc this is an inefficiency of aerobic respiration
What do we use to build new enzymes damaged by respiration?
ATP - an example of inefficiency in respiration
what must be properly eliminated to keep the pH balance in the cell? What happens if the pH changes in the cell?
CO2
enzymes do not function correctly at incorrect pH levels. This causes people to feel dysfunctional.
What is complex II in the ETC?
Succinate dehydronase
What is Complex III in the ETC?
Cytochrome C Oxidoreductase
What is Complex IV in the ETC?
Cytochrome C reductase
True or False: The ETC’s basic function is to transport electrons through membrane proteins which then produce H+.
True
What is the function of Fe-S clusters in Complexes I, II, and III?
they transport electrons
True or False: The end of the ETC in Complex IV means electrons are acted upon by copper, accepted by O2, and forms H20.
True
Cytochrome C transports an electron between which two complexes in the ETC?
Complex III and IV
