Oxidative phosphorylation and the Electron Transport Chain Flashcards
what occurs in glycolysis
Pyruvate and 2 ATP molecules are generated per molecule of glucose as well as 2 molecules of NADH. Takes place in the cytoplasm of all cells and does not require oxygen
what occurs in the TCA / Krebs cycle
Uses the pyruvate molecules from glycolysis to generate 2 ATP as well as several molecules of FADH2and NADH for the electron transport chain. Takes place in the mitochondrial matrix and requires oxygen.
what occurs in Oxidative phosphorylation/the ETC
Uses the NADH and FADH2molecules formed during glycolysis and TCA, creates a proton gradient that ultimately leads to the production of about 34 molecules of ATP. Takes place in the mitochondrial matrix and requires oxygen.
what by product molecules can be produced which can be oxidised to release further energy
NADH and FADH2
how many of NADH and FADH 2 shuffle through the ETC
34 ATP = 10 NADH (3 ATP per NADH)
2 FADH2 (2 ATP per FADH2)
what is NADH
Nicotinamide adenine dinucleotide
(NAD + Hydrogen) and is a co-enzyme found in all living cells
what reaction is NADH involved in
NADH is usually involved in REDOX reactions as a transporter of electrons.
NAD+ is its oxidized form, NADH is the reduced coenzyme form (OIL RIG)
NAD+ (Oxidised state = can accept electrons!)
What is FADH2
Flavin adenine dinucleotide, another important co-enzyme found in all living cells
what does FADH2 transport
electrons
FAD is its oxidized form, (wants to accept electrons!)
FADH2 is the reduced coenzyme form (accepts two electrons and two protons)
What reaction changes NAD+ to NADH
Redox reaction - NAD+ accepts 2 electrons causing it to be negatively charged
Then accepts a positively charged hydrogen ion (H+) from surrounding environment to give neutral NADH
What reaction changes NAD+ to NADH
Redox reaction - NAD+ accepts 2 electrons causing it to be negatively charged
Then accepts a positively charged hydrogen ion (H+) from surrounding environment to give neutral NADH
when is NADH produced
produced in glycolysis and Krebs cycle
what 2 joined nucleotides does NADH have
adenine and nicotinamide
where is FADH2 produced
produced in Krebs cycle
What 2 joined nucleotides does FADH2 have
adenine and flavine mononucleotide
what 2 closely connected components in the Oxidative Phosphorylation
the ETC and chemiosmosis
what does NADH and FADH2 do in Oxidative Phosphorylation
transfer electrons to oxygen across several complexes in the electron transfer chain, being returned to their oxidised forms (NAD+ and FAD)
why is oxygen important in Oxidative Phosphorylation
final acceptor of electrons and is reduced to H2O in the production of ATP
where does oxidative phosphorylation occur
the mitochondrion
how is a proton gradient H+ established
as a result of electron transport and redox potential
what is redox potential
(E)– a measure of a substance’s affinity for electrons
what 2 processes occur in Oxidative Phosphorylation
1- produces a proton concentration gradient by the respiratory ETC, a series of enzyme complexes embedded in the inner mitochondrial membrane, oxidises NADH and FADH2. Electrons are passed from the reduced coenzymes to O2.
2- The proton concentration gradient is a reservoir of free energy – protons are channelled back across the inner membrane through an enzyme complex, ATP synthase
how are electrons transferred from NADH and FADH2 to oxygen along the ETC
using 4 multi-subunit large enzyme complexes (I, II, III, IV) and 2 mobile electron carriers (coenzyme Q and cytochrome c)
what are redox reactions (exergonic or endogenic)
exergonic; the energy released is used to ‘pump’ protons across the inner mitochondrial membrane
Are Electrons directly transferred from NADH or FADH2 to O2
no
Instead, NADH and FADH2 pass electrons to members of the ETC which are sequentially reduced then oxidised
O2 is the final acceptor of electrons
what are small electron carriers
membrane proteins
what is Chemiosmosis
is the movement of ions across a semipermeable membrane
what occurs in complex 1
NADH dehydrogenase catalyses the transfer of electrons from NADH to coenzyme Q (CoQ)
Acts as a proton pump.
what occurs in complex 2
succinate-CoQ oxidoreductase catalyses the transfer of electrons to coenzyme Q (CoQ)
and the product is fumarate + CoQH2.
CoQH2 is called ubiquinol, a reduced state of CoQ
what is complex 3
When CoQH2 is re-oxidised to CoQ the H+ passes out the other side of the membrane (second reaction)
what is the complex 4
cytochrome c oxidase, catalyses the transfer of electrons from cytochrome c to oxygen.
Completes the oxidation of original NADH molecule
Proton pumping also takes place (third reaction)
How does proton pumping generate ATP molecules?
Oxidative phosphorylation couples the oxidation of NADH and FADH2 with the phosphorylation of ADP to generate ATP
what is ATP Synthase
A multi-subunit protein - ATPase
This enzyme has a channel for protons to flow from the intermembrane space into the matrix.
Synthesis is in direct response to oxidation of NADH and FADH2
how many moles of ATP does the complete oxidation of 1 molecule of glucose generates
38
in cells using the glycerol phosphate shuffle what is the ATP yield
2- overall ATP yield in these cells is 36 per mole of glucose
