5 Mitochondria And Oxidative Phosphorylation Flashcards
Q: Draw an annotated diagram of a mitochondrion.
A: inner mitochondrial membrane folds = cristae
Matrix
Q: Which proteins are located on the inner mitochondrial membrane?
A: electron transport chain
Q: What are this evolutionary origins of the mitochondria?
A: evolutionary descendant of prokaryote
Consumed by eukaryote and established endosymbiotic relationship
Q: What is the evidence supporting the endosymbiosis theory?
A: mitochondria can arise only from preexisting mito and chloro
Possess own genome- circular with no associated histones (resembles prokaryotes)
Q: Define the chemiosmotic theory and describe the 2 steps.
A: transfer of electrons down electron transport chain through series of oxidation and reduction reactions that releases energy
- Movement of protons from within mito matrix into intermembrane space controlled by electron transport chain
- Pumped protons re enter mito matrix via specific proton channel associated with ATP synthase enzyme
Q: What does the movement of protons fro, the mitochondrial matrix to the intermembrane space establish?
A: proton/potential/ pH gradient
Q: What is the force that drives the movement of protons back into the mito matrix?
A: proton motive force
Q: What does the electron transport chain consist of?
Q: 3 complexes and 2 mobile carriers (act as electron carriers)
Q: What are the 3 membrane complexes that make up the ETC?
A: NADH dehydrogenase complex
Cytochrome b-c1 complex
Cytochrome oxidase complex
Q: What are the 2 mobile carriers that make up the ETC?
A: coE Q (ubiquinone)
Cytochrome C
Q: What occurs as you go along each unit in the ETC and why is this useful?
A: each increases in election affinity which means electron movement can follow a logical order
More positive redox potential
Q: As electrons pass along the ETC, what happens to protons?
A: pumped from mito matrix to intermembrane space
Q: What is ubiquinone and what does it do?
A: electron carrier
Transfers electrons from NADH dehydrogenase complex to cytochrome b-c1
Q: How is ubiquinone bound to the lipid membrane?
A: hydrophobic tail
Q: Why is oxygen the ideal terminal electron acceptor?
A: has high affinity for electrons which provides a driving force for oxidative phosphorylation
Q: How is water formed at the end of the ETC?
A: cytochrome oxidase being the last membrane complex in the ETC receives 4 electrons from cytochrome C (cycle repeats so 2 each time)
Cytochrome c passes it on to oxygen to form water
Q: Draw the electron transport chain.
A: NADH dehydrogenase complex, ubiquinone, cytochrome b-c1 complex, cytochrome C, cytochrome oxidase complex
Q: How are electrons transferred in the electron transport chain?
A: by redox and oxidation with NAD+/NADH and FAD/FADH2
Q: Do electrons lose or gain energy as they move down the ETC?
A: lose
Q: Which unit of the ETC is the entry point for electrons donated by FADH2?
A: ubiquinone
Q: Draw a labelled diagram for ATP synthase.
A: f0= a b c
F1= alpha beta gamma
Each have 3 subunits
Q: How do protons enter ATP synthase and what happens?
A: pore
Disc of c subunits rotates
Gamma subunit in f1 is fixed to the disc so rotate with it
Alpha and beta subunits in f1 are locked into position by the b subunit meaning alpha and beta can’t rotate
B subunit is anchored into subunit a in membrane
As gamma rotates (asymmetrical axle) the b subunit undergoes structural changes of its catalytic portions which changes its affinity for ATP and ADP
torsional energy flows from the catalytic subunit into the bound ADP and Pi to promote ATP formation
Q: How can ATP be hydrolysed?
A: ATP synthase working in opposite direction as protons are pumped out
Q: How can mitochondrial respiration be examined experimentally?
A: The Oxygen Electrode measures the oxygen concentration in a solution housed in a small chamber
base of chamber= teflon membrane with two electrodes beneath= Platinum (Pt) cathode and silver (Ag) anode
a small voltage is applied between the anode and cathode
oxygen diffused through the teflon membrane and is reduced to water at the platinum cathode:
O2 + 4H+ + 4e- -> 2H2O
The silver anode is slowly oxidised to AgCl:
4Ag+ 4Cl- -> AgCl + 4e-
The resulting current is proportional to the oxygen concentration in the sample chamber.
We can use the oxygen electrode to dissect various components of the electron transport chain
->first step is to prepare the suspension of mitochondria from tissue and place into chamber
