Topic 5 Flashcards by Elise Dunbar

where does glycolysis occur?

in the cytosol

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what is glycolysis?

a series of coupled redox reactions that release the free energy of glucose and transfers some of the released energy into other molecules

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what type of reaction is glycolysis?

a combustion reaction where glucose is burned in oxygen to produce carbon dioxide and water

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how do coupled redox reactions work (glycolysis)?

nonpolar covalent bonds in the reactants are broken
-polar covalent bonds in the products are formed
-bonding electrons between the carbon atoms in glucose have moved farther away from the C atoms in CO2 so glucose is oxidized
-bonding electrons between the O atoms of O2 have moved closer to O atoms in water so oxygen is reduced

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what do electron carrier coenzymes generate?

reduction potential

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what is reduction potential?

high energy electrons that have lots of potential energy

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what goes into glycolysis per glucose?

2 ATP
2 NAD+

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what is produced from glycolysis per glucose?

4 ATP
2 NADH

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what is substrate level phosphorylation?

transfer of a phosphate from an organic molecule to ADP to make ATP

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why is glycolysis partial glucose oxidation?

not much ATP has been made and there’s a lot of energy left in pyruvate
-cell needs to remove pyruvate otherwise the product will build up
- the cell needs to restore NAD+ to continue glycolysis

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what happens to pyruvate in eukaryotic and prokaryotic cells when oxygen is limited?

pyruvate enters a fermentation pathway

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what does the inner mitochondrial membrane do?

electron transfer
ATP synthesis by ATP synthase

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what is the matrix and what does it do?

it’s the space inside both membranes
-is responsible for pyruvate oxidation and citric acid cycle

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how does pyruvate reduction during fermentation work?

fermentation oxidizes NADH to NAD+ so glycolysis can continue to make ATP in the absence of O2
-removes pyruvate from the cell
-Fermentation doesn’t directly produce ATP

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what is a bridge reaction?

pyruvate is oxidized to acetyl CoA in the matrix
-connects glycolysis to the Krebs cycle

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what is input in the bridge reaction per pyruvate?

1 pyruvate
1 CoA
1 NAD+

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what is input in the bridge reaction per glucose?

2 pyruvate
2 CoA
2 NAD+

what is output in the bridge reaction per pyruvate?

1 CO2
1 NADH
1 acetyl CoA

what is output in the bridge reaction per glucose?

2 CO2
2 NADH
2 acetyl CoA

what is the citric acid cycle/ the Krebs cycle?

finishes oxidation of glucose
-8 connected reactions (5 coupled)
-catabolise reactions that oxidize acetyl CoA to CO2

what are steps in the krebs cycle?

acetyl CoA (2C) is added to oxaloacetate (4C) to make citrate (6C)
-citrate is oxidized to oxaloacetate

what is produced during the Krebs cycle?

2CO2 per acetyl coa
3 NADH
1 ATP
1 FADH2

what is the electron transport chain?

located in the IMM
consists of 4 protein complexes
2 electron taxis
transport electrons from NADH and FADH2 to O2 using redox reactions

what are the two electron taxis in ETC?

ubiquinone
cytochrome C

what is Ubiquinone?

a hydrophobic electron taxi

how does ubiquinone work?

taxis electrons from complex 1 to complex 2 taxis electrons from complex 2 to complex 3 when its reduced it takes an H+ from matrix and releases it in the IMS when its oxidized

what is cytochrome C?

a hydrophilic electron taxi?

how does cytochrome C work?

taxis electrons from complex 3 to complex 4

how is electron flow redox driven?

e flow to increasingly electronegative prosthetic groups until they reach the final e acceptor (o2) -each time an e transfer occurs, the e moves closer to the atomic nucleus and free energy is released to work

how does the ETC pump proteins?

e flow is coupled to the pumping of protons from the matrix to the IMS to generate an electrochemical gradient

complexes one and two of etc

NADH in the matrix donates electrons to complex 1 -H+ are pumped from the matrix to the IMS by complex 1 -FADH2 in the matrix donates electrons to complex 2

complex 3 and 4 of ETC

electrons flow from complex 3 to complex 4 -H+ are pumped from the matrix into the IMS by complex 4 -complex 4 donates electrons to O2 which is reduced to H2O

when is H+ concentration lowered in the matrix?

pumped across the membrane (c1, uq, c4) used to reduce O2

what is the H+ electrochemical gradient called?

the proton motive force (PMF)

how is the PMF used for chemiosmosis?

potential energy in the PMF powers ATP synthase as H+ move through ATP synthase to the matrix the energy is released to drive synthesis of ATP

ATP synthase

as the H+ move through the channel free energy drives the catalytic part

how much ATP is produced in aerobic respiration?

approximately 32 ATP can range to 38

why can ATP production vary so much?

some of the PMF is used for active pumps some NADH and FADH2 have other uses in the cell

what happens when you don't need ATP?

glucose can be stored as a polymer (starch or glycogen) -triglycerides can be generated for long term storage

aerobic respiration in prokaryotes?

all metabolism occurs in the cytosol and on the cell membrane

characteristics of anaerobic respiration?

only in prokaryotes evolved when o2 wasn't abundant

final electron acceptors for anaerobic respiration?

SO4, NO3