Ch.19 Oxidative Phosphorylation Pt.2 Flashcards
Which subunits of F₁ are catalytic?
The three β subunits are what bind to ADP.
What occupies each of the three β subunits?
One is empty.
One has ADP.
One has ATP.
What does the 𝝲 subunit of F₀ do? (2)
It rotates causing conformational change in the β subunits. This drives catalysis (ADP→ATP).
It also releases ATP!!
What causes the 𝝲 subunit of F₀ rotate?
It rotates because the entire F₀ subunit rotates.
Protons bind to F₀ subunit → rotates one revolution → causes 𝝲 to rotate and perform catalysis
What is F₀ rotation driven by?
Driven by the chemiosmotic gradient.
How many hydrogens must flow through ATP Synthase to produce one ATP? Why is this not stoichiometric (3)?
about three (NOT stoichiometric)
Because of the gradient itself, adenine translocase, and phosphate transporter.
What is the adenine translocase?
An antiporter in the inner mitochondrial membrane that transports ATP out and ADP in via passive transport.
What does adenine translocase do to the chemiosmotic gradient?
It lowers the chemiosmotic gradient because ATP with a -4 charge goes out and ADP with a -3 charge comes in. It works with the gradient.
What is phosphate transporter?
A symporter in the inner mitochondrial membrane that brings a phosphate and a proton into the mitochondrial matrix via passive transport.
What does phosphate transporter do to the chemiosmotic gradient?
It lowers the chemiosmotic gradient because a proton is moving into the matrix with the gradient. (lowers the difference across the membrane)
What is the purpose of the malate-aspartate shuttle?
It is the mechanism by which NADH from the cytosol (like from glycolysis) enters the mitochondria to partake in the electron transport chain.
What are the steps of the malate-aspartate shuttle? (6)
- NADH in the cytosol reduces oxaloacetate to malate
- malate transported into mitochondrial matrix
- malate is oxidized to oxaloacetate in mito. reforming NADH (NADH reductive power now in mito)
- oxaloacetate is converted to aspartate in mito.
- aspartate is transported into cytosol
- aspartate converted to oxaloacetate in cytosol
Why do you get less ATP from NADH originating in the cytosol?
It needs to undergo conversion and transport via the malate-aspartate shuttle so it loses some of its reductive power.
How is the ETC coupled to ATP synthesis?
By the chemiosmotic gradient.
Is the ETC regulated?
No. If there is NADH and oxygen, ETC will happen. If there is ADP, Pᵢ and a chemiosmotic gradient, ATP synthesis will happen.
What is the uncoupler we talked about with regard to hibernating bears and what is its purpose?
Thermogenin. It produces heat so hibernating animals stay warm.
What is thermogenin and what does it do?
It is an integral membrane protein in the inner mitochondrial membrane. It is a proton pore that allows protons back into the mitochondrial matrix without ATP Synthase. Energy released in the form of heat.
How many ATP does glucose produce?
about 32
What links metabolic pathways together? (2)
ATP and ADP.
