Oxidative Phosphorylation Flashcards
(22 cards)
How does ATP synthase work
A multi subunit complex made up of 4 polypeptide parts.
Protons move one by one into binding sites on the rotor, causing it to spin.
This catalysed ATP production from ADP and Pi.
How does the ETC pump hydrogen
Certain members of ETC accept and release protons as well as electrons.
Electron transfers cause H+ to be taken up and released into the surrounding solution.
Electron carriers are arranged in inner mito membrane to accept H+ from mito membrane and deposit it in the intermembrane space.
Proton-motive force.
What is the H+ gradient
An energy converter that uses the exergonic flow of electrons from NADH and FADH2 to pump H+ across the membrane.
From mitochondrial space to the intermembrane space.
How is the H+ gradient maintained
ATP synthase provides a route through the membrane for H+ using exergonic flow of H+
How many kcal of energy does a complete oxidation of a mole of glucose release under standard conditions
-686
What is the efficiency of respiration and how do you calculate it
34% or 0.34
7.3 kcal per mole of ATP x 32 moles of ATP per mole of glucose / 686 kcal per mole of glucose
Where doesthe rest of the lost energy that should be stored in glucose go
Lost as heat.
Just to maintain body temp or dissipated through sweating and other cooling mechanisms
How do some animals generate heat without any ATP production and how is this beneficial
A protein called the uncoupling protein allows protons to flow back down their conc gradient without generating ATP.
Buildup of ATP would cause cellular respiration to be shut down by regulatory mechanisms.
Why is oxygen key in the ETC
It’s the final acceptor that pulls electrons down the ETC because it’s so electronegative
Why do muscle fatigue and get sore a day after exercise
Lactate build up is carried away to the liver when aerobic respiration can occur and converted back to pyruvate.
Pyruvate then enters mitochondria and completes cellular respiration.
Causes trauma to small muscle fibres and leads to inflammation and pain.
What about glycolysis suggests that it evolved very early in the history of life
It’s the most widespread metabolic pathway - thought to have been used to make ATP before oxygen was present in the earths atmosphere
If a bacteria went from aerobic to fermentation yet still produced the same amount of ATP, how would the glucose consumption be affected
It would increase by 16x as 32 ATP per mole of glucose in aerobic and 2 ATP per mole of glucose in fermentation
What are the functions of cytochromes
Help electrons move rapidly.
Ferry electrons between large complexes.
Pump protons from mitochondrial matrix to inter membrane space.
Why does FADH release energy to complex 2 at a lower energy level than NADH
They each donate the same amount of electrons, ETC provides less energy from ATP synthase when electron donor is FADH2 than NADH
What powers chemiosmosis
The difference in H+ ion concentration gradient.
Uses this to power ATP synthase.
Roughly how does ATP synthase work
H+ ions flowing down enter a stator.
H+ ions enter the binding sites in the rotor, changing subunit shape, spinning the rotor.
H+ ions pass through the second channel in stator into the mitochondrial matrix.
Rotor spinning spins internal rob, extending into the knob below it.
Turning of rod activates catalytic sites in knob that produces ATP from ADP and Pi.
During respiration, in which way does energy flow
Glucose —> NADH —> ETC —> proton motive force —> ATP
How many ATP molecules does oxidative phosphorylation produce
26 or 28 ATP molecules
What factor can affect ATP yield
The type of shuttle used to transport electrons from cytosol to mitochondria.
FAD = 1.5 ATP molecules
NAD+ = 2.5 ATP molecules.
Proton-motive force drives other work.
Eg to power mitochondrion uptake of pyruvate from cytosol.
How does alcohol fermentation regenerate NAD+
Pyruvate releases carbon dioxide = acetaldehyde —reduced by NADH—> ethanol
How does lactic acid fermentation regenerate NAD+
Pyruvate —reduced by NADH—> lactate
What is needed for fermentation to work as a respiration mechanism
Sufficient supply to NAD+ to accept electrons during oxidation step.
Mechanism to recycle NAD+ from NADH
