L15: Oxidative Phosphorylation Flashcards
Define prosthetic groups
Non-proteins that attach to proteins to assist them
Components of the ETC
1) Proteins/protein complex embedded in the inner mitochondrial membrane containing prosthetic groups
2) Non-protein bound mobile element, CoQ
Example of H acceptors (carry electrons)
Flavins & Ubiquinone
1 mononucleotide & 1 dinucleotide within the ETC
FMN: Flavin mononucleotide
FAD: Flavin adenine dinucleotide
How does FMN & FAD differ?
R groups
What are cytochromes?
Proteins containing haem and carry an electron on the Fe2+ iron
What do iron-sulphur proteins contani?
Fe-S clusters anchored via the side chain of cysteine residues
3 features of ubiquinone (CoQ)
1) Not bound to protein
2) Freely mobile in the inner mitochondrial membrane
3) Transfers electrons from Complex I & II of ETC to Complex III
What is redox potential a measure of?
Electron affinity of a molecule
What happens if redox potential is more negative?
More likely a molecule is to pass on electrons
What happens if redox potential is more negative?
More readily a molecule will accept electrons
How does stepwise breakdown release energy?
In useable small ‘packages’
What is energy released by electron transport used for?
To transport protons from the matrix to the intermembrane space
Which complex of the ETC does not pump protons?
Complex II
Why doesn’t Complex II pump protons?
Difference in redox potential between FAD & Q does not provide enough energy for transfer of protons across inner membrane
How do protons creating a rotary motion when flowing ‘through’ ATP synthase?
F0 & F1
1) F0 spins as H+ passes through
2) F1 dosn’t spin, held stationary by a ‘stator’
Stator prevents rotation of F1 subunit
2 main subunits of ATP synthase
F0 & F1
What is the F0 subunit of ATP synthase?
Embedded in the inner membrane & rotates as protons flow ‘through’
Which complex is ATP synthase?
Complex V
Name for coupling of ATP synthesis to electron transport
Oxidative phosphorylation (OXPHOS)
What does oxidative mean in OXPHOS?
Each component of the ETC is oxidised as they pass electrons
What does phosphorylation mean in OXPHOS?
ADP is phosphorylated using Pi to create ATP
Role of an inhibitor of an ETC complex
- Reduces transfer of electrons to/from that complex
- Reduces ATP synthesis
- Lead to production of damaging radicals
What does uncoupling agents do in the inner mitochondrial membrane?
Create channels to be permeable to protons
