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57 Cards in this Set

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Cellular Respiration
Slow oxidation of energy rich molecules to extract potential energy and convert it into ATP
A catabolic process... Some reactions involved still have a positive delta G
Three parts:
Glycolysis
CA cycle
ETC
Controlled Combustion
Energy is slowly released in a step wise fashion with the energy being transferred from molecule to molecule
Many small little activation energies to be overcome
Direct Burning
Consists of 1 large EA to be overcome
All energy is released as heat = bad because it is not an efficent method of energy transfer
Substrate Level Phosphorylation
A mode of ATP synthesis that requires an enzyme that transfers a phosphate group from a high energy substrate to a molecule of ADP
Produces ATP
Energy Coupling
ATP is brought into close contract with a reactant molecule involved in an endergonic reaction
When ATP is hydrolyzed, the phosphate group is transferred to the reactant molecule
The reactant molecule is then phosphorylated, making it less stable
ATP
Contains a large amount of fee energy bc they possess high energy phosphate bonds
ATP
Contains large amounts of free energy due to high energy phosphate bonds
Consists of 5 carbon sugar, ribose, linked to the nitrogenous base adenine, and a chain of three phosphate groups
Catabolic Pathways
Negative delta G
Breaking something down
Energy is released
Reactions can be exergonic or endergonic
Anabolic Pathways
Positive delta G
Building something up
Energy is consumed
NAD+ vs FADH
NAD+ = 1 proton, 2 electron carrier
FADH2 = 1 electron carrier
Where does glycolysis take place?
The cytosol
Glycolysis description
Anaerobic - does not require oxygen
NET = 2 ATP and 2 NADH
Final Product = 2 pyruvate molecules
Glycolysis I
2 molecules of ATP are consumed
ATP phosphorylates glucose
Kinase
ATP is consumed because of the enzyme kinase
Why is glucose phosphorylated in glycolysis I?
1) Makes glucose more reactive
2)Makes glucose charged to prevent it from diffusing outside the cell
Glycolysis II
Four ATP and 2NADH molecules are produced
No carbon is lost - all 6 of the carbons in glucose are converted into two 3-carbon pyruvates
How is ATP produced in glycolysis II?
Substrate level phosphorylation
Pyruvate Oxidation
Converts pyruvate into actetyl-CoA
The product of glycolysis, pyruvate, must pass through both membranes - from the cytosol to the matrix
Passing through the inner membrane required a membrane carrier
Pyruvate Oxidation Steps
1) Begins with a decarboxylation reaction where the carboxyl group is removed
2) The remaining two carbons are oxidized to produce acetate
3) A dehydrogenation reaction leads to the transfer of two electrons and one proton to NAD+, forming NADH
4) The acetyl group then reacts with coenzyme A
Where does the citric acid cycle occur?
In the mitochondrial matrix
Citric Acid Cycle
Consists of 8 enzyme catalyzed reactions
The reactions result in the oxidation of the acetyl groups into carbon dioxide
NET/Actetyl CoA = 3 NADH, 1 FADH2 & 1 ATP
***Recall the the acetyl groups contain two carbons. THEREFORE THERE ARE TWO CO2 MOLECULES RELEASED
Substrate level phosphorylation is used once again
The Pyruvate Dehydrogenase Complex
A complex of 3 enzymes that transform pyruvate into acetyl CoA
"pyruvate decarboxylation"
Acetyl CoA is then used in the citric acid cycle
*LINKS glycolysis and the CA cycle
Pyruvate is in the cytosol of the cell and must go into the mitochondrial matrix
Pyruvate Dehydrogenase Deficiency
The enzyme responsible for transforming pyruvate into acetyl-coA is defective
Without functional dehydrogenase, pyruvate builds up in the cells, triggering fermentation
This leads to a build up of lactic acid
The brain needs glucose since it is only receiving pyruvate it gets messed
The ability to generate ATP is restricted which causes brain misfunction
Ketogenic Diet
A diet high in fat with little carb
Respiratory Breakdown of Fats
Triglycerides are hydrolyzed into glycerol and fatty acids
Glycerol in converted
FA are split into two carbon fragments, which enter the citric acid cycle as acetyl coA
Fatty acid tails are removed
Respiratory Breakdown of Protein
Proteins are hydrolyzed into AA before oxidation
Amino group is removed as it enters as acetyl co A
High amount of ATP compared to ADP
Cell is in energy abundant condition
High amount of ADP compared to ATP
Cell is in energy poor condition
Cellular respiration will speed up so ATP can be raised
High NADH compared to NAD+
Cell has lots of reducing power
High NAD+ compared to NADH
Cell doesen't have enough reducing power
Glycolysis and the CA cycle will speed up
No effect on ETC
High lactate compared to pyruvate
Not a lot of oxygen present
Citric acid cycle will speed up
High pyruvate compared to lactate
Lots of oxygen present, fermentation will speed up
Where does the CA cycle occur?
In the aqueous compartment of the matrix of the mitochondria
ETC Goals
All of the carbon in glucose has been ocidized and released as carbon dioxide following the CA cycle
Potential energy originally present in glucose now exists in the form of NADH and FADH2
ETC extracts the energy from NADH and FADH2 to make additional ATP
Electron shuttles
Ubiquinone and cytochrome C
4 Protein complexes of ETC
NADH dehydrogenase
Succinate dehydrogenase
Cytochrome complex
Cytochrome oxidase
Ubiquinone
A hydrophobic molecule found in the core of the membrane
Shuttles electrons from complex I & II to complex III
Cytochrome C
Located in the intermembrane space
Transfers electrons from complex III to complex IV
Role of NADH in ETC
Purpose is to oxidize NADH
1) NADH dehydrogenase removes an electron from NADH, releasing NAD+ and a proton
2) The electron is used to reduce Q
3) Q ferries the electron to the cytochrome complex by cytochrome C
4) Electron flows through cytochrome C
5) Electron combines with oxygen to produce water
Driving Force of Flow of Electrons down ETC
Spontaneous process
Complexes I, III, IV are bound to their specific prosthetic groups
The prostheric groups alternated between reduced oxidized and reduced states: they donate and recieve electrons
Electron carriers are ordered from low to high free energy... or from low to high redox potential
Go down the chain = more electronegative
Electron Carriers
Do not get oxidized/reduced
No intrinsic electron transfer ability
FMN has a greater affinity then NADH
Electrons are donated to oxygen
Where does ETC occur
The inner mitochondrial membrane
Chemiosmosis
Electron transfer from NADH or FADH2 does not create ATP
The free energy of NADH & FADH2 is used to pump protons across the inner membrane
Protons accumulate in the inner membrane space & pH drops
This is a source of potential energy
Complexes I and IV use the energy released from electron transport to pump protons
Ubiquinone picks up protons from the matrix as they accept electrons
PMF
Stored energy do to a chemical and electrical gradient across the membrane
PMF & electrical circuits
Lightbulb = electrons flow in a cycle, passing over LB and causing it to glow
PMF = H+ flow in a cycle, passing over synthesis of ATP
What type of process is the synthesis of ATP?
Endergonic
Glutamate and ETC
Rate of respirtation decreases
BC a proton gradient is being established
There is no ADP so ATP synthesis cant be driven
Gets harder and harder to pump protons
ADP and ETC
Decreases severely
ADP can synthesize ATP, and the PMF is dissipated though ATP synthase
CA CYCLE in pro and euk
Euk = matrix
Pro = cytosol
Oligomyocin and ETC
Rate slows down
Prveents protons from moving through ATP synthase
ATP synthesized and the rate is slower because it is harder to respirate
Uncoupler and ETC
Speeds up
Allows for free diffusion of protons across membrane
PMF drops alot
highest rate of ETC
Oxidative Phosphorylation
The mode of ATP synthesis that is linked to the oxidation of energy rich molecules by an ETC
Relies on the action of ATP synthase
Oligomyocin
An inhibitor of ATP synthase
Binds to the proton pore of ATP synthase and prvents protons from flowing back through the pore
Effect of uncoupling agents on ATP synthesis
Gives protons a choice of going through the uncoupling protein or through ATP synthase
Energy of a proton gradient is lost as heat
Non-shivering thermogenesis = heat production throught he regulation of an uncoupling protein
Not enough oxygen =
Pyruvate does not enter the mitochondria, stays in the cytosol and is converted into ethanol and lactate
Role of NADH in sensing hypoxia
H1F beta is always made and detected
H1F alpha is degraded in the presence of oxygen
Effect of H1F1 on pyruvate metabolism
Drives the synthesis of kinase
This specific kinase phosphorylates the dehydrogenase complex and shuts it down
Now pyruvate cant enter the mitochondria, fermentation occurs