Oxidative Phosphorylation Flashcards
What is the net gain after the TCA cycle and before?
6-2 ATP = 4ATP
10x NADH
10x H+
2x FADH2
6x CO2
How many and what type of electrons are carried by NADH and FADH2?
2 high-energy electrons
What are the electrons used for?
Reducing O2 to H2O
Their energy is used to pump H+ from matrix to intermembrane space
What energy is used to phosphorylate ADP to ATP?
Protons flowing back across the membrane following their concentration gradient
How does NADH from the cytoplasm reach the mitochondrial matrix?
Malata-Aspartate Shuttle
NADH cannot cross inner mitochondrial membrane
How does the malate-aspartate shuttle work?
Oxaloacetate generates malate in cytosol by converting NADH to NAD+
Malate transporters transfer malate to mitochondrial matrix
Malate conversion to oxaloacetate in TCE cycle generates NADH
In ADDITION to malate made from fumarate
What is the electron transfer potential of NADH and FADH2 converted to, in oxidative phosphorylation?
Phosphoryl transfer potential of ATP
How is electron transfer potential measured?
Measured by REDOX potential of a compound
How is phosphoryl transfer potential measured?
Measured by freen energy change for hydrolysis of ATP
What is the redox potential of a compound?
Measure for how readily X donates an electron in comparison to HYDROGEN
Negative potential = lower affinity for electrons than HYDROGEN
What does a negative redox potential mean?
Reduced form has a lower affinity for electrons than HYDROGEN
What redox potential do strong reducers and oxidizers have?
Reducers have negative redox potential = tend to donate electrons
Oxidizers have positive potential = tend to accept electrons
What does it mean to be a reducer and an oxidizer?
Strong reducers = tend to donate electrons
Strong oxidizers = tend to accept electrons
How is the energy of electrons converted into energy of ATP?
Chmiosmotic coupling???
What are the stages of chemosmotic coupling?
Electron transport = electrons flow from NADH and FADH2 to O2
Energy is used to pump H+ out of mitochondrial matix
Electrochemical gradient of H+ across mitochondrial inner membrane = energy stored in this gradient can be used to synthesize ATP
How are electrons passed fown the ETC?
Because carrier have increasingly POSITIVE redox potentials
Oxygen is the ultimate electron acceptor
Why do protons want to flow back into mitochondrial matrix?
Because it has a relatively more negative charge since there are now less H+
Describe ATP synthase orientation
F1 subunit protrudes into mitochondrial matrix
F0 subunit is hydophobic complex in inner membrane (
What is the stator and rotor?
Stator is the bulb part
Rotor is made up of subunits c, gamme and epsilon = the base and stalk
What can inhibit the electron transport chain?
Cyanide, azie and CO = inhibit transfer of electron to O2
No proton gradient can be formed = so no ATP made
What is non-shivering thermogenesis?
Non-shivering thermogenesis (NST) is a process in which the body generates heat without the mechanical activity of shivering.
This process primarily occurs in brown adipose tissue (BAT), a special type of fat that is specialized for heat production, rather than energy storage.
The main mechanism that drives NST is the uncoupling of oxidative phosphorylation in mitochondria, a process that allows for the generation of heat instead of ATP.
How does uncoupling of oxidative phosphorylation cause non-shivering thermogenesis?
Instead of the energy from the proton gradient being used to produce ATP, it is dissipated as heat.
What is the role of unoupling protein (UCP) in non-shivering thermogenesis?
UCP1 allows protons to flow back into the mitochondrial matrix without passing through ATP synthase. This disrupts the normal ATP production process, causing the energy from the proton gradient to be released as heat instead of being stored as ATP.
What stimulates the activation of uncoupling protein?
When the body needs to generate heat (for example, during cold exposure), the sympathetic nervous system releases norepinephrine. This stimulates brown adipose tissue to activate UCP1, leading to the uncoupling of the ETC and the production of heat.
What is dinitrophenol (DNP)?
Artificial uncoupler
Acts as protonophore in inner mitochondrial membrane = creating proton leak
What is dinitrophenol (DNP) used as anti-obesity drug?
Increases metabolic rate
But can cause death by overheating = so no longer used
Why do mice with UCP-3 gene deleted have tolerance to MDMA (ecstasy)?***
UCP-3 is expressed in skeletal muscle = allowing muscle thermogenesis and limiting free radical production
Without UCP-3 = modified mouse became OBESE
DONT KNOW
